agriculture
Article
Combined Effects of Drought and Soil Fertility on the Synthesis
of Vitamins in Green Leafy Vegetables
Taewan Park 1, Sahrah Fischer 1 , Christine Lambert 2 , Thomas Hilger 1,* , Irmgard Jordan 3 and
Georg Cadisch 1
1 Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim,
70593 Stuttgart, Germany
2 Department of Nutritional Science, University of Hohenheim, 70593 Stuttgart, Germany
3 Alliance Bioversity International and CIAT, Food Environment and Consumer Behaviour Lever,
00621 Nairobi, Kenya
* Correspondence: thomas.hilger@uni-hohenheim.de
Abstract: Green leafy vegetables, such as Vigna unguiculata, Brassica oleraceae, and Solanum scabrum,
are important sources of vitamins A, B1, and C. Although vitamin deficiencies considerably affect
human health, not much is known about the effects of changing soil and climate conditions on
vegetable vitamin concentrations. The effects of high or low soil fertility and three drought intensities
(75%, 50%, and 25% pot capacity) on three plant species were analysed (n = 48 pots) in a greenhouse
trial. The fresh yield was reduced in all the vegetables as a result of lower soil fertility during
a severe drought. The vitamin concentrations increased with increasing drought stress in some
species. Regardless, the total vitamin yields showed a net decrease due to the significant biomass loss.
Changes in vitamin concentrations as a result of a degrading environment and increasing climate
change events are an important factor to be considered for food composition calculations and nutrient
balances, particularly due to the consequences on human health, and should therefore be considered
in agricultural trials.
Keywords: drought; environment; food composition; food security; human health; nutrition security;
plant nutrition; soil fertility; vitamin A; vitamin B1; vitamin C
Citation: Park, T.; Fischer, S.;
Lambert, C.; Hilger, T.; Jordan, I.;
Cadisch, G. Combined Effects of
Drought and Soil Fertility on the
Synthesis of Vitamins in Green Leafy 1. Introduction
Vegetables. Agriculture 2023, 13, 984. Changes in crop growth conditions do not only affect yields, they also influence the
https://doi.org/10.3390/ nutrient content of the crop. In areas with a high prevalence of nutritional deficiencies in the
agriculture13050984 human population, even small differences in the amounts of vitamins due to less favorable
Academic Editor: Marcin Rapacz growing conditions may influence the deficiency rate. Low (pro-)vitamin A (including
pro-vitamin A carotenoids, such as β-carotene) intake is one of the most significant threats
Received: 14 March 2023 to health in Sub-Saharan Africa (SSA). In this region, up to 20% of children below five
Revised: 22 April 2023 years of age suffered from a vitamin A deficiency in 2016 [1]. Deficient intake of vitamin
Accepted: 27 April 2023 A impairs visual functions and growth, and increases the risk for respiratory infections,
Published: 29 April 2023 which increases the risk of morbidity and mortality [2]. Vitamin B1 (thiamine) is a com-
mon deficiency in staple food-dominated diets, exacerbated by practices such as milling
grains [3]. A vitamin B1 deficiency can lead to severe neurological and cardiovascular
Copyright: © 2023 by the authors. effects and even death [3]. Vitamin C (ascorbic acid) deficiency is relatively common in
Licensee MDPI, Basel, Switzerland. middle- to low-income countries. In Kampala, Uganda, for example, 70% of pregnant
This article is an open access article women were deficient in vitamin C [4]. Vitamin C deficiencies in the diet, in addition to the
distributed under the terms and negative effects of an actual vitamin C deficiency, may contribute to a lower bioavailability
conditions of the Creative Commons of essential minerals from diets, such as Fe and Zn [5].
Attribution (CC BY) license (https:// Green leafy vegetables are rich in micronutrients and other phytochemicals, such as
creativecommons.org/licenses/by/ vitamins, which are vital for human health. Many studies show the benefits of increasing
4.0/). green leafy vegetable consumption on human health. An increased and regular intake of
Agriculture 2023, 13, 984. https://doi.org/10.3390/agriculture13050984 https://www.mdpi.com/journal/agriculture
Agriculture 2023, 13, 984 2 of 15
green leafy vegetables is, for example, associated with a lower risk for cardiovascular dis-
eases (CVDs) [6]. The authors of a nutrition study in Tanzania confirmed that an increased
consumption of green leafy vegetables can contribute to a lower prevalence of anemia and
micronutrient deficiencies, particularly in resource-poor communities [7].
Plants contain a wide range of metabolites that have antioxidant potential [8,9] and
are pre-cursors of vitamins, essential to human health. Plants produce co-enzymes and
antioxidants, such as ascorbic acid, thiamine, and β-carotene, for a specific purpose [10],
e.g., to protect themselves from environmental stressors, such as drought or poor soil
fertility. Drought causes the production of reactive oxygen species (ROS), which, in turn,
can lead to oxidative damage to the photosynthesis apparatus, and, hence, to reduced
primary production [11]. Different carotenes and ascorbic acid are the main ROS detoxifying
compounds [10,11]. Thiamine is also an important component of plant stress response,
in addition to its other functions [12]. For lack of a unifying term in plant nutrition, the
vitamin pre-cursors will be referred to as vitamins in this study.
Soil fertility provides the basis of plant production by providing plants with sufficient
nutrients and water. Varying levels of soil fertility affect food yields, as well as food quality
in terms of mineral nutrient concentrations [13]. Furthermore, vitamin concentrations
were found to be inversely affected by nitrogen (N) fertilizer application [14,15], thereby
suggesting the possibility that soil fertility could also affect vitamin concentrations.
Climate change has led to an increase in extreme weather events, such as prolonged
and more frequently occurring droughts [16]. While the effects of different climate change
variables (increasing temperatures, drought, increasing CO2 and O3) on mineral and
macronutrient concentrations in different plant parts have been measured [17–19], the
effects on vitamin concentrations have not been covered thus far.
Both climate change and soil degradation represent two of the biggest challenges for
the sustained production of high quantity and quality foods [20], while concurrently being
partially responsible for both occurrences. This paper will focus on the following research
question: (i) Does soil fertility, (ii) water stress (drought), and the combination of drought
stress and varying soil fertility significantly affect the contents of β-carotene, ascorbic acid,
and thiamine in the leaves of three green leafy vegetables (Brassica oleraceae L., Solanum
scabrum L., Vigna unguiculata L.)?
As the production of vitamins is a stress reaction, especially to stressors such as
drought, an increase in vitamin concentrations in all green leafy vegetables with increasing
drought is expected. Soil fertility is key for plant nutrient intake, and largely provides the
nutrients needed to produce vitamins. Therefore, it is expected that in high soil fertility, the
vitamin concentrations will be higher in all the drought severities than in low soil fertility
of the same drought severity. The fresh weight is expected to decrease with increasing
drought and decreasing soil fertility.
2. Materials and Methods
This study was part of the project “Education and Training for Sustainable Agriculture
and Nutrition in East Africa (EaTSANE)”. Since the main research area for the EaTSANE
project was East Africa, namely the areas of Teso South, Kenya (a region with low soil
fertility) and Kapchorwa, Uganda (a region with high soil fertility), the trial was set up to
mimic the local conditions. Three local green leafy vegetables were analysed: sukuma wiki
(Brassica oleraceae L.), black nightshade (Solanum scabrum L.), and cowpea (Vigna unguiculata
L.), using soils with properties similar to the soils found in the East African research areas.
The temperature in a greenhouse of the University of Hohenheim, Germany was
adjusted to 22 ◦C, which is the mean of the average temperature during the growing
season in Kapchorwa and Teso South (Table S1). Daylight was allowed from 6 am to
6 pm, as in the target areas. The greenhouse temperature and humidity were monitored
during the entire trial using a TGP-4500 Tiny Tag Plus 2 (Gemini Data Loggers, Ltd.,
Chichester, UK). Two soils were selected to represent the soils of Kapchorwa, Uganda and
Teso South, Kenya [21]. The first soil collected showed similarities to the soils with lower
Agriculture 2023, 13, 984 3 of 15
fertility ferralsols in Teso South and was classified as an endostagnic alisol collected in
Tauchenweiler, Germany (48◦47′13.3” N and 10◦02′18.9” E). In this paper, the soil with
lower fertility will be referred to as “infertile”. The second soil, comparable to a higher
fertility nitisol, such as from Kapchorwa, Uganda, was an endoleptic cambisol, and was
collected in Höwenegg, Germany (47◦54′55.7” N and 8◦44′25.7” E) (Table S3). In this paper,
the soil with higher fertility will be referred to as “fertile”.
The soils gathered in Germany show similar properties to the soils of Teso South,
Kenya and Kapchorwa, Uganda. The low fertility soils both feature sandy soils, whereas
the high fertility soils feature loamy clays. While the pH of both of the low fertility soils is
acidic (German alisol: 4.0; Kenyan ferralsol: 4.94), the pH of the high fertility soil was 5.6 in
both cases [13]. Both of the low fertility soils showed a very low amount of soil organic
matter, whereas the soils of higher fertility showed a higher amount.
The three green leafy vegetables were planted into pots on 17 September 2019. The
plastic pots (37.5 cm height and 16 cm diameter) were filled with 1.5 kg gravel as drainage,
with a depth of 5 cm. The two soil types were dried and sieved (0.9 cm2 sieve type), and
5.5 kg of each soil was placed into the different pots. After sowing, the soil was covered
by a thin layer of sand (~10 mm, 80 g) to prevent excessive evaporation and soil cracking.
Each pot was sown with four seeds of each green leafy vegetable, and then later thinned
out, leaving one seedling per pot.
The pot water capacity (PC) was analysed using the gravimetric methods provided
by [22]. Three treatments in the watering regime were used: 75% PC as control, 50% PC as
mild stress, and 25% as severe drought stress. A total of 144 pots were used, 48 per plant
species, with two soil fertilities (fertile and low fertility soil), and three drought intensities
(control 1, control 2, mild, and severe) (Table S2). The double control group was used
to improve the statistical power [23]. Each treatment had six replicates organised into a
randomized complete block design (Figure S1). After plant germination, all the pots were
weighed and watered every two days to maintain the assigned drought conditions.
Fifty-one days after sowing, flower buds of the control plants became visible. The
entire aboveground part of all the pots was harvested and frozen after recording their fresh
weight. The belowground biomass (roots) were washed, then dried with paper towels, and
the fresh weight recorded. The fresh leaves were stored at −80 ◦C and then lyophilized
using a freeze dryer (LyoQuest laboratory freeze dryer, Telstar, Spain) for 24 h, and the dry
weight was recorded. The samples were then ground, homogenized, and stored in the dark
at −20 ◦C.
The plant water use efficiency (WUE) was calculated as the ratio between the above-
ground biomass (yield) and water use (evapotranspiration). WUE is generally high when
the plants are exposed to drought conditions or are drought tolerant [24], and is, therefore,
used to evaluate drought resistance [25]. The WUE of the yield was determined by the
division of the fresh yield by water consumption [24].
The concentrations of thiamine, β-carotene, and ascorbic acid were measured in the
leaf samples using high performance liquid chromatography (HPLC) at the Institute of
Nutritional Sciences, University of Hohenheim. The HPLC data were recorded and anal-
ysed using the Shimadzu LabSolutions Software (Version 5.54, Shimadzu Deutschland
GmbH, Duisburg, Germany). The chromatographic analysis of the vitamins was conducted
using the Shimadzu HPLC system. The Shimadzu HPLC system consisted of a DGU 20A3
Degassing Unit, an LC-20AT Pump, a SIL-20AC HT AutoSampler, and a CBM-20-A Commu-
nication Module. The method for thiamine analysis was based on the European Standard
(DIN EN 14122:2014) of vitamin B1 determination [26]; however, minor adaptations were
made. β-carotene was measured using the method of [27]. The retinol equivalents (REs)
of β-carotene were calculated using a factor 1 µg RE = 6 µg β-carotene [28]. Ascorbic acid
was measured using the method of [29].
Since C3 plants close their stomata to reduce water loss during water-limiting condi-
tions, 13CO2 fixation is decreased and δ13C is discriminated due to reduced CO2 diffusion in
and out of the leaves [30]. Therefore, δ13C isotope discrimination has been used to measure
Agriculture 2023, 13, 984 4 of 15
water stress in C3 plants [31]. The δ13C contents of green leafy vegetables were analysed
by comparing the control (75% PC) to the drought treatments (50% and 25% PC) using
randomly selected subsamples (n = 4 per PC of each species) of the green leafy vegetable
samples. The selected subsamples were measured with a Euro EA Elemental Analyser
(Euro Vector, Pavia, Italy) coupled to a Finnigan Delta IRMS (Thermo Fischer Scientific,
Waltham, MA, USA) at the core facility of the University of Hohenheim.
The fulfilment of the recommended nutrient intake (RNI) of vitamin A, ascorbic acid,
and thiamine by consuming 150 g of green leafy vegetables (fresh weight) as an average
serving size was calculated for female adults (19–50 years) [28].
SAS (SAS® University Edition, SAS Institute Inc., Cary, NC, USA) was used for the
statistical analysis. The fresh yield, belowground biomass, number of nodules, irrigation
water added, water use efficiency (WUE), pot capacity (PC), thiamine, β-carotene, and
ascorbic acid were subjected to analysis of variance (ANOVA) for each treatment. ANOVA
using PROC GLIMMIX was used to compare the treatments between the plant species
and the significance of factors by an F-test at α = 0.05. A two-factorial model was fitted as
an equation (SUPPL MAT). The interaction of the treatment and species was significant;
therefore, the cell means were compared using a SLICE statement with the SLICEBY
options, i.e., SLICEBY = treatments and SLICEBY = species, in the GLIMMIX procedure.
The means of yield and WUE differences between the different soil fertility and drought
conditions were compared. The vitamin concentrations were expressed on a fresh weight
basis. The absolute vitamin amounts (mg per pot) were calculated for thiamine, β-carotene,
and ascorbic acid by the multiplication of the fresh leaf yield (g/pot) by the vitamin content
(mg/100 g FW) and divided by 100 [32]. The vitamin data were used to analyse whether
the changed vitamin contents compensate for the treatments’ changed yield. An analysis
of covariance (ANCOVA) using PROC GLM was used to compare the treatment means
adjusted for a covariate soil fertility within the plant species.
3. Results
3.1. Plant Yield Analysis
All the fresh leaf yields of the three green leafy vegetables were significantly higher
(B. oleraceae: p < 0.01, V. unguiculata: p < 0.001, S. scabrum: p < 0.0001) in fertile soil than in
low fertility soil with the same watering regime, with the exception of B. oleraceae with a
75% pot capacity (PC), where the difference was not significant (Table 1). Regardless of the
soil fertility, the fresh leaf yields of the green leafy vegetables decreased with an increasing
level of drought (Table 1 and Figure S1). However, the yield losses caused by drought did
not differ significantly between the fertile and low fertility soils (Figure 1).
Table 1. Fresh leaf yield (g/pot), belowground biomass (g/pot FW), nodule number per pot, total
irrigation water added (ml/pot), and water use efficiency (WUE: fresh yield/water use, g/L) in
Vigna unguiculata, Brassica oleraceae, and Solanum scabrum under two soil fertilities with three watering
regimes (75% pot capacity (PC), 50% PC, and 25% PC).
Fresh Yield Belowground No. of Irrigation Water WUE
(g/pot) (g/pot FW) Nodules Added (mL/pot) (g/L)
Vigna unguiculata
Fertile soil
75% PC 25.2 ± 1.3 c 12.0 ± 1.1 bc 11.2 ± 3.4 a 2882 ± 115 a 8.8 ± 2.0 def
50% PC 18.6 ± 1.9 d 9.0 ± 1.5 cd 6.3 ± 2.1 b 1871 ± 162 bc 10.1 ± 2.9 cdef
25% PC 12.2 ± 1.9 ef 5.2 ± 1.5 de 1.2 ± 0.5 bc 832 ± 162 de 15.3 ± 2.9 bcd
Infertile soil
75% PC 13.8 ± 1.3 e 2.0 ± 1.1 ef 0.0 c 2192 ± 165 b 6.3 ± 2.0 ef
50% PC 7.9 ± 1.9 fg 1.0 ± 1.5 ef 0.0 c 1239 ± 163 d 6.2 ± 2.9 ef
25% PC 2.5 ± 1.9 h 0.9 ± 1.5 f 0.0 c 405 ± 162 ef 8.8 ± 2.9 cdef
Agriculture 2023, 13, 984 5 of 15
Table 1. Cont.
Fresh Yield Belowground No. of Irrigation Water WUE
(g/pot) (g/pot FW) Nodules Added (mL/pot) (g/L)
Brassica oleraceae
Fertile soil
75% PC 41.5 ± 1.7 a 9.4 ± 1.3 c - 2842 ± 142 a 14.9 ± 2.5 bcd
50% PC 32.8 ± 2.1 b 10.2 ± 1.6 c - 2080 ± 179 bc 16.4 ± 3.2 bc
25% PC 12.6 ± 2.1 ef 1.4 ± 1.6 ef - 398 ± 179 ef 43.2 ± 3.2 a
Infertile soil
75% PC 40.3 ± 1.4 a 3.9 ± 1.1 ef - 2928 ± 120 a 13.9 ± 2.1 bcde
50% PC 15.0 ± 1.9 de 1.0 ± 1.5 ef - 1204 ± 162 d 11.8 ± 2.9 cdef
25% PC 4.7 ± 1.9 gh 0.6 ± 1.5 f - 342 ± 162 f 14.1 ± 2.9 bcde
Solanum scabrum
Fertile soil
75% PC 35.0 ± 1.3 b 21.5 ± 1.1 a - 2844 ± 115 a 12.4 ± 2.0 cde
50% PC 25.9 ± 1.9 c 15.4 ± 1.5 b - 1783 ± 162 c 14.8 ± 2.9 bcd
25% PC 17.4 ± 1.9 de 10.4 ± 1.5 c - 917 ± 162 d 20.6 ± 2.9 b
Infertile soil
75% PC 16.5 ± 1.3 de 3.0 ± 1.1 ef - 1804 ± 115 c 9.0 ± 2.0 cdef
50% PC 4.8 ± 1.9 gh 0.9 ± 1.5 f - 1013 ± 162 d 4.8 ± 2.9 f
25% PC 1.1 ± 1.9 h 0.7 ± 1.5 f - 209 ± 162 f 14.4 ± 2.9 bcd
Analysis of variance (ANOVA) using PROC GLIMMIX was used to compare the treatments between plant species
and the significance of factors by an F-test at α = 0.05. LS-means ± SE within the column with the same letter are
not significantly different (p < 0.05).
B. oleraceae showed the highest yield loss with increasing drought regardless of the
soil fertility, as evidenced in the steeper slope increase in the linear regression (Figure 1).
Nevertheless, B. oleraceae obtained a higher total fresh yield under no drought (control,
75% PC) (p < 0.0001) and mild drought (50% PC) (p < 0.0001) conditions than the other
two green leafy vegetables (Table 2). In contrast, S. scabrum had the highest yield loss
with decreasing soil fertility under all watering regimes, shown by the highest interceptor
differences between the regression lines of fertile and low fertility soils, while B. oleraceae
showed the lowest yield loss by different soil fertility (Figure 1). The belowground biomass
was significantly lower in the low fertility soil than in the fertile soil for all the green leafy
vegetables (all p < 0.0001) (Table 1). Only severe drought (25% PC) significantly (p < 0.05)
decreased the belowground fresh weight of all the species in the fertile soil (Table 1).
Table 2. Levels of β-carotene contents and retinol activity equivalents (RAE) of V. unguiculata,
B. oleraceae, and S. scabrum under two soil fertilities with three watering regimes (75% pot capacity
(PC), 50% PC, and 25% PC).
β-Carotene RAE β-Carotene RAE
(mg/100 g FW) (µg/100 g FW) (mg/Fresh Yield) (µg/Fresh Yield)
Vigna unguiculata
Fertile soil
75% PC 7.37 ± 0.26 bc 614 ± 21 bc 1.86 ± 0.09 bc 155 ± 7 bc
50% PC 7.64 ± 0.36 bc 636 ± 30 bc 1.42 ± 0.13 de 118 ± 10 de
25% PC 8.04 ± 0.36 b 670 ± 30 b 0.97 ± 0.13 f 80 ± 10 f
Infertile soil
75% PC 6.89 ± 0.26 cd 574 ± 21 cd 0.97 ± 0.09 f 81 ± 7 f
50% PC 6.41 ± 0.36 de 534 ± 30 de 0.57 ± 0.13 g 47 ± 10 g
25% PC 4.92 ± 0.36 gh 410 ± 30 gh 0.12 ± 0.13 h 10 ± 10 h
Brassica oleraceae
Fertile soil
75% PC 4.02 ± 0.32 hi 335 ± 26 hi 1.66 ± 0.11 cd 138 ± 9 cd
50% PC 4.11 ± 0.40 ghi 343 ± 33 ghi 1.36 ± 0.14 de 114 ± 12 de
25% PC 3.66 ± 0.40 i 305 ± 33 i 0.46 ± 0.14 gh 38 ± 12 gh
Agriculture 2023, 13, 984 6 of 15
Table 2. Cont.
β-Carotene RAE β-Carotene RAE
(mg/100 g FW) (µg/100 g FW) (mg/Fresh Yield) (µg/Fresh Yield)
Brassica oleraceae
Infertile soil
75% PC 4.03 ± 0.27 hi 336 ± 22 hi 1.62 ± 0.10 cd 135 ± 8 cd
50% PC 3.48 ± 0.36 i 290 ± 30 i 0.55 ± 0.13 g 46 ± 10 g
25% PC 3.61 ± 0.36 i 301 ± 30 i 0.17 ± 0.13 h 14 ± 10 h
Solanum scabrum
Fertile soil
75% PC 7.59 ± 0.26 bc 632 ± 21 bc 2.66 ± 0.09 a 221 ± 7 a
50% PC 8.09 ± 0.36 b 674 ± 30 b 2.11 ± 0.13 b 176 ± 10 b
25% PC 9.48 ± 0.36 a 790 ± 30 a 1.62 ± 0.13 cd 135 ± 10 cd
Infertile soil
75% PC 7.08 ± 0.26 cd 590 ± 21 cd 1.17 ± 0.09 ef 97 ± 7 ef
50% PC 5.99 ± 0.36 ef 499 ± 30 ef 0.31 ± 0.13 gh 26 ± 10 gh
25% PC 5.13 ± 0.45 fg 428 ± 37 fg 0.06 ± 0.16 h 5 ± 13 h
Analysis of variance (ANOVA) using PROC GLIMMIX was used to compare the treatments between plant species
Agriculture 2023, 13, x FOR PEER REVIEW 6 of 16 
 and the significance of factors by an F-test at α = 0.05. LS-means ± SE within the column with the same letter are
not significantly different (p < 0.05).
 
Figure 1. Fresh yFieilgdu (rge/p1o. tF) roefs they igerleden(g l/eapfoy tv)eogfetthabelegsr eBe. nolleeraacfeyaev, eVg. eutnagbuleicsulBa.tao,l earnadc eSa.e s,cVab. ruunmg,u iculata, and S. scabrum,
along with the paolto ncagpwaciitthy t(h%e) pfort cthape afceirtyile( %(L))f aonrdth ienfertiille (SL)) saonild. Ainnfaelrytislies (oSf) csovila.rAiantea l(yAsNis-of covariate (ANCOVA)
COVA) was perfworamsepde. rTfhoer mreegdre.sTsihoen rleingerse isns ieoanchli npleasnitn speeaccihesp alraen ptasrpaellceile. sRaegrerepssairoanl lfeolr.mRuelgarse ssion formulas and R2
and R² are givena. Treheg itvriepnle.  Tashteertirsikp ilnedaiscatetersis skiginnidfiiccaantcees asti gpn <i fi0c.0a0n1c. e at p < 0.001.
B. oleraceae showed the highest yield loss with increasing drought regardless of the 
soil fertility, as evidenced in the steeper slope increase in the linear regression (Figure 1). 
Nevertheless, B. oleraceae obtained a higher total fresh yield under no drought (control, 
75% PC) (p < 0.0001) and mild drought (50% PC) (p < 0.0001) conditions than the other two 
green leafy vegetables (Table 2). In contrast, S. scabrum had the highest yield loss with 
decreasing soil fertility under all watering regimes, shown by the highest interceptor dif-
ferences between the regression lines of fertile and low fertility soils, while B. oleraceae 
showed the lowest yield loss by different soil fertility (Figure 1). The belowground bio-
mass was significantly lower in the low fertility soil than in the fertile soil for all the green 
leafy vegetables (all p < 0.0001) (Table 1). Only severe drought (25% PC) significantly (p < 
0.05) decreased the belowground fresh weight of all the species in the fertile soil (Table 1).  
Within all the vegetables, the WUE changed more drastically in the drought treat-
ments in fertile soil than in the drought treatments on infertile soil with increasing drought 
intensity. The exception to this is S. scabrum, where the changes in fertile and infertile soil 
with increasing drought intensity were similar.  
The WUE of B. oleraceae was higher than V. unguiculata and S. scabrum under severe 
drought (25% PC) in the fertile soil, which was the highest WUE at 43.2 g/L (F-test, p < 
 
Agriculture 2023, 13, 984 7 of 15
Within all the vegetables, the WUE changed more drastically in the drought treatments
in fertile soil than in the drought treatments on infertile soil with increasing drought
intensity. The exception to this is S. scabrum, where the changes in fertile and infertile soil
with increasing drought intensity were similar.
The WUE of B. oleraceae was higher than V. unguiculata and S. scabrum under severe
drought (25% PC) in the fertile soil, which was the highest WUE at 43.2 g/L (F-test,
p < 0.0001) among the three green leafy vegetables under all the treatments, while the yield
was not significantly different (p < 0.05) (Table 1). In the low fertility soil, B. oleraceae had
the highest water demand under control (75%), and the yield was higher than the other
green leafy vegetables (Table 1).
3.2. ∆13C Measurement as an Indicator for Water Stress
All three green leafy vegetables showed an increase in their δ13C signature, i.e., less
negative δ13C values, with the decreasing irrigated water amount, i.e., increasing drought
intensities (Figure S2). Under drought conditions, V. unguiculata had the highest changes of
δ13C values, ranging between −31.76‰ and −26.67‰ (R2 = 0.611, p = 0.0027) for leaves
under both soil fertilities, followed by B. oleraceae with ranges between −34.48‰ and
−32.62‰ (R2 = 0.619, p = 0.0024). S. scabrum also showed an increase of δ13C values, but
the change was not significant (Figure S2).
3.3. Effects of Drought and Soil Fertility on Vitamin Concentrations
3.3.1. Thiamine
The thiamine concentrations of B. oleraceae (R2 = 0.47; p < 0.05) and V. unguiculata
(R2 = 0.54; p < 0.01) nearly doubled in response to increasing drought intensities in the low
fertility soil (Figure 2). In V. unguiculata, the thiamine concentrations were two times higher
than B. oleraceae with the combination of low fertility soil and drought, as the regression
line’s slope was double (Figure 2). However, in the fertile soil, the thiamine concentrations
did not respond to drought in B. oleraceae or only slightly increased in V. unguiculata
(R2 = 0.46; p < 0.05) (Figure 2). In S. scabrum, the thiamine concentration was not affected
by drought, but was significantly higher (p = 0.005) in the low fertility soil compared to
the fertile soil (Figure 2). Despite the increase in the thiamine concentration, the total
thiamine yields (fresh leaf yield (g/pot) x thiamine concentration as mg/100 g fresh weight
(FW)) of V. unguiculata (R2 = 0.60; p < 0.001) and S. scabrum (R2 = 0.64; p < 0.001) were
significantly lower in the low fertility soil than in the fertile soil and fell with increasing
drought (Figure 3).
There was no interaction between drought and soil fertility in the thiamine yield
(Figure 3). In B. oleraceae, an increased thiamine concentration through the drought and
low soil fertility compensated for the decline in fresh yield in the lower soil fertility, as the
thiamine yield of B. oleraceae showed no differences between soil fertilities (Figures 1–3).
3.3.2. Beta-Carotene (Pro-Vitamin A)
Interactions between soil fertility and drought were found in the β-carotene concen-
trations of V. unguiculata (p = 0.0038) and S. scabrum (p < 0.0001) (Figure 2). The β-carotene
concentrations in V. unguiculata (R2 = 0.24; p < 0.05) and S. scabrum (R2 = 0.40; p < 0.01) fell
significantly due to the combination of low soil fertility and increasing drought, while the
concentrations rose in the fertile soil under drought conditions, but only significantly in
S. scabrum (R2 = 0.40; p < 0.001) (Figure 2). When comparing the β-carotene concentration
changes in the low fertility soil, the β-carotene concentrations of V. unguiculata and S.
scabrum decreased significantly from the control (75% PC) to severe drought (25% PC)
(Table 2). In the fertile soil (S), the β-carotene concentration of S. scabrum increased during
the drought treatment (Table 2). B. oleraceae β-carotene concentrations were not significantly
affected by soil fertility and drought treatments (Figure 2 and Table 2). Despite the inverse
effects of the soil fertility by drought on the β-carotene concentrations of V. unguiculata and
S. scabrum (Figure 2), there was no interaction between the soil fertility and drought on
Agriculture 2023, 13, x FOR PEER REVIEW 8 of 16 
 
Agriculture 2023, 13, 984 3.3. Effects of Drought and Soil Fertility on Vitamin Concentrations 8 of 15
3.3.1. Thiamine  
The thiamine concentrations of B. oleraceae (R2 = 0.47; p < 0.05) and V. unguiculata (R2 
the β-carotene yields (Figure 3). Furthermore, the β-carotene yields of all three green leafy
ve=g 0et.5ab4l; eps w< e0r.e01h)ig nheearrinlyt hdeofuebrtlieleds ionil rtheaspnoinnsthe etolo wincferretailsitiyngso dilr(oSu) (gFhigt uinrete3n).sities in the low 
fertility soil (Figure 2). In V. unguiculata, the thiamine concentrations were two times 
3.h3i.3g.hAers ctohrabnic BA.c oidleraceae with the combination of low fertility soil and drought, as the re-
greIsnsiBo.no lleirnacee’ase s, tlhoepaes wcoarbs idc oacuidblceo (nFteignut srieg n2i)fi. cHanotwlyedveecr,e ainse tdhwe iftehritnilcer esaosiiln, gthdero tuhgiahmt ine con-
(Rc2en=tr0a.3ti9o;nps <di0d. 0n1o),t arnedsptohnedc otonc denrotruagtihotn iwn aBs. coolenrsaicseteane tolyr ohniglhye srlignhtthlye  fienrctrileeaseodil in V. un-
regguaircdulleastsao (fRth2 e=d 0r.o4u6g; hpt <in 0te.0n5si)t y(F(Figiguurree 2)).. IIn  cSo.n stcrasbtr,uinmV, .tuhneg tuhiciualmatian, teh ceoanscoernbtircaatciiodn was not 
coanffceecntterdat iboyn dinrcorueagshetd, bwuitth wseavs esriegdnriofiucagnhttl(y2 5h%igPhCer) i(np t=h e0l.0o0w5)fe irnti ltihtye slooiwl ( R
2
fer=til0i.t4y5 ;soil com-
pp<a0r.e0d1) ,tow thhilee ftehreticloe nscoeinl t(rFaitgiounrew 2a)s. nDoetsspigitnei fithcaen itnlycraefafescet eidn bthyed trhoiuagmhtinine tchoenfceerntitlreation, the 
soil (Figure 2). The ascorbic acid concentration of S. scabrum rose with drought (R2 = 0.13;
total thiamine yields (fresh leaf yield (g/pot) x thiamine concentration as mg/100 g fresh 
p < 0.05) but was not affected by soil fertility (Figure 2). The ascorbic acid yield was higher
inwtehiegfhetr t(iFleWso))i lotfh Van. uinngtuhieculolawtaf e(R
2
rtil =it y0.s6o0i;l pa n<d 0.d0e0c1r)e aasnedd Sw. istchabdrruomug (hR
2 
t i=n 0e.a6c4h; pgr <e e0n.001) were 
lesaifgynviefigceatnabtllye (lFoiwguerre i3n) .tThhee ltohwre efegrrteielintyle saofyilv tehgaenta binle sthseh ofweretdilen osoinilt earnacdti ofenllb ewtwitehe nincreasing 
thdersoouilgahntd (Fdirgourgeh 3t )o.n  the ascorbic acid yields (Figure 3).
 
FiFgiugruer2e. 2(A. (–AI)–RI)e laRtieolnasthioipnsbheitpw beeentwveiteanm vinitcaomntienn cto(mntge/n1t0 (0mggF/1W0)0o gf gFrWee)n olef agfyreveeng eletaabfyle sveBg. etables B. 
oloelrearcaecaee,aeV,. Vu.n guunigcuuliactual,aatna,d aSn.dsc Sab. rsucmab,raunmd,p aontdca ppoatc ictyap(%ac)iitny t(w%o) sioni ltsw, foe rstoilielsa,n fderintifleer tainleds oinilfse. rtile soils. 
AAnanlyaslyissoisf coofv caorivaateri(aAteN (CAONVAC)OwVaAs)p werafosr mpeerdf.oBromxepdlo. tBs o(Ax,pI)loshtso w(Ain, gI)t hsehcoowmipnagr itshoen coof mvitpaamriinson of vita-
comntienn ctobnytesnoitl bfeyr tsioliitly f.eArtifilittyp.l oAt fi(Ft) pwloats (aFd)a wptaesd atdoaSp.tsecdab trou mS. assccaobrrbuimc  aacsicdocrobnicte anctisdd cuoenttoenntos due to no 
significant effect by the soil fertility. Regression respective formula and R2
significant effect by the soil fertility. Regression respective formulaa arendgi vRe2n a.rTer igpilvee, nd.o Tubrilpe,le, double, 
anadndsi nsginlegales taesritsekrsisiknds iicnadteicsaigten isfiicgannicfiecaatnpce< a0t.0 p0 1<, 0<.00.0011,, a<n0d.0<10, .a0n5,dr e<s0p.e0c5t,i vreelsyp. eLcrteifveerlsyt.o Lf erretfileers to fertile 
sosiol,ilw, hwehreearseaSsr eSf erresfetorsi ntfoe ritnilfeerstoiille.  soil. 
 
Agriculture 2023, 13, x FOR PEER REVIEW 9 of 16 
 Agriculture 2023, 13, 984 9 of 15
 
FFiigguurree 33.. RReelalatitoionnshsihpipbe btweteweneevnit avmitianmyiinel dysie(lmdgs/ (pmogt)/pofogt)r eoefn glreeaefyn vleegaefyta bvleegseBt.aoblelerasc eBa.e ,oVle.raceae, V. un-
guunigcuuilcautlaa,t aa, nandd SS.. ssccaabbrruumm, a, nadnpdo pt coatp caaciptyac(%ity)  in(%tw) oins otiwls,of esrotiillesa, nfderitnifleer tailneds oiinlsf.eArtnilaely ssoisilosf. Analysis of 
ccoovvaarriiaattee( A(ANNCCOOVAV)Aw) aws paesr pfoerrmfoedrm. Tehde. rTeghree srseiognrelsinseiosnin leinacehs pinla netascphe cpielasnatr esppaercailelesl .aArefi pt arallel. A fit 
pplloott ((bboottttoomm-le-lfet)ftw) aws aasd aapdteadptteodth teot hthiaem tihnieaymieilndeo yf iBe.lodle orafc Bea.e odluereatcoeaneo dsiugen itfioc annot seiffgenctifiocf asonitl effect of soil 
fertility. Regression respective formula and R2 are given. The triple asterisk indicates significance at
fertility. Regression respective formula and R2 are given. The triple asterisk indicates significance at 
p < 0.001.
p < 0.001. 
3.4. Fulfilment of Recommended Nutrient Intake (RNI) by Green Leafy Vegetables under Different
GrowtThhCeorned witioanss no interaction between drought and soil fertility in the thiamine yield (Fig-
ure 3F)o. rInβ -Bca. roolteernaeceinatea, kaen,  1i5n0cgreoafsferdes hthlieaamveisnoef cVo. nuncegunitcrualatitoanan tdhrSo. uscgabhr uthmer edarcohuedght and low 
smooilr efethratinli2ty00 %coomf pvietanmsainteAd’s fRoNr It,hreeg daredclleisnseo finth efrteresaht myeienltds, winh itlhe eB .loolewraecrea seoreila cfheerdtility, as the 
more than 100% of the RNI for vitamin A in 150 g of fresh leaves (Table 3). The thiamine
tchoinacmenintrea tyioinelsdo foBf .Bo.l eorlaecreaaceeaane dshVo. wunegdu incuol adtaiffseigrneinficceasn tblyetiwncereeans esdoiwl fiethrtdilriotiuegsh (tFiingures 1–3). 
the low fertility soil (Figure 2). However, S. scabrum could only contribute less than 6%
3o.f3t.2h.e BReNtaI-fCoar rvoittaemnein (PBr1ob-Vy i1t5a0mginf rAes)h leaves (Table 3). For ascorbic acid intake, B.
oleracIenaetereraacchtieodnms obreettwhaenen20 s0o%ilo ffeRrNtilIitiny 1a5n0dg dofrothuegfhrets wh leeraev efsouunndde rina twheel l-βw-caaterroetdene concen-
tcroantdioitniosn oifn Vt.h uenfgerutiicleuslaotial. (Ap d=d 0it.i0o0n3a8ll)y a, nB.do lSe.r ascceaabercuomul d(pp <r o0v.0id0e01m)o (rFeigthuarne 120)0. %Thoef β-carotene 
vitamin C’s RNI, regardless of the soil fertility, even when the ascorbic acid concentration
concentrations in V. unguiculata (R2 = 0.24; p < 0.05) and S. scabrum (R2
was decreased by drought (Table 3). In V. unguiculata, the ascorbic acid conten t=i n0.14500; gp < 0.01) fell 
soifgfnreifishcalenatvlyes drueaec thoe dth1e7 0c%omobf iRnNaItiionnt hoef lloow fseortiill ifteyrstioliiltyu nadnedr sinevcerereasdirnogu gdhrto(u25g%ht, while the 
cPoCn)c(eTnabtrlaet3io).nIsn raodsdei tionn t,hSe.  sfcearbtriulem scooiul ludnpdroevr ideroouvgerh1t 6c0o%ndofitRioNnIsf,o bruast conrblyic saicgidnificantly in 
Sco. nscceanbtrruamtio (nRin2 =1 500.4g0o;f pfr e<s h0.l0e0av1e) s(uFnigduerrese 2v)e.r eWdhroeung hctocmonpdairtiionngs (t2h5e% βP-Cca),rroetgeanrdel ecsosncentration 
cohfathnegseosi linfe rtthileit ylo(wTa bfelert3i)l.ity soil, the β-carotene concentrations of V. unguiculata and S. sca-
brum decreased significantly from the control (75% PC) to severe drought (25% PC) (Table 
2). In the fertile soil (S), the β-carotene concentration of S. scabrum increased during the 
drought treatment (Table 2). B. oleraceae β-carotene concentrations were not significantly 
affected by soil fertility and drought treatments (Figure 2 and Table 2). Despite the inverse 
effects of the soil fertility by drought on the β-carotene concentrations of V. unguiculata 
and S. scabrum (Figure 2), there was no interaction between the soil fertility and drought 
on the β-carotene yields (Figure 3). Furthermore, the β-carotene yields of all three green 
leafy vegetables were higher in the fertile soil than in the low fertility soil (S) (Figure 3). 
  
 
Agriculture 2023, 13, 984 10 of 15
Table 3. Percentage of recommended nutrient intakes (RNI) for vitamin content (mg/150 g FW for
thiamine and ascorbic acid and µg/150 g FW for RAE) and vitamin yield (mg/plant for thiamine
and ascorbic acid and µg/plant for RAE) of V. unguiculata, B. oleracea, and S. scabrum under two soil
fertilities (fertile; L and infertile soil; S) with three watering regimes (75% pot capacity (PC), 50% PC,
and 25% PC).
% of RNI 1 % of RNI 1
for Vitamin Content for Vitamin Yield
(mg or µg/150 g FW) (mg or µg/Plant)
Thiamine Ascorbic Acid RAE 2 Thiamine Ascorbic Acid RAE 2
Vigna unguiculata
Fertile soil (L)
75% PC 13.0 118 184 2.4 21 31
50% PC 14.7 101 191 1.8 11 24
25% PC 20.2 105 201 1.7 9 16
Infertile soil (S)
75% PC 15.5 75 172 1.6 8 16
50% PC 19.5 92 160 1.1 6 9
25% PC 33.0 170 123 0.5 2 2
Brassica oleraceae
Fertile soil (L)
75% PC 9.8 238 101 2.7 68 28
50% PC 9.7 237 103 2.3 53 23
25% PC 10.2 132 92 1.2 51 8
Infertile soil (S)
75% PC 11.3 189 101 3.0 15 27
50% PC 12.0 117 87 1.5 14 9
25% PC 20.6 135 90 0.6 4 3
Solanum scabrum
Fertile soil (L)
75% PC 2.9 152 190 0.7 37 44
50% PC 3.4 127 202 0.6 22 35
25% PC 4.3 180 237 0.4 17 27
Infertile soil (S)
75% PC 4.9 122 177 0.5 13 19
50% PC 5.3 125 150 0.2 5 5
25% PC 5.5 166 128 0.1 1 1
1 RNI, recommended nutrient intake; values for female adults (19–50 years) (WHO & FAO, 2004); 2 RAE, retinol
activity equivalent, bioconversion of ingested β-carotene to retinol based on equivalency factors, for which 1 µg
RAE = 12 µg β-carotene (WHO & FAO, 2004).
3.5. Effects of Drought under Two Soil Fertilities on Fresh Yield and Vitamin Contents
Table 4 shows a summary of the drought’s effect on the fresh yield and vitamin contents
of three green leafy vegetables under two different soil fertility conditions. For the fresh
yield, the three green leafy vegetables were significantly decreased by drought (Figure 1
and Table 4). The β-carotene content was significantly increased in S. scabrum in fertile soil,
while the content was significantly decreased by drought in V. unguiculata and S. scabrum
in infertile soil (Figure 2 and Table 4). The ascorbic acid content was significantly increased
in S. scabrum during drought, regardless of the soil condition, and in V. unguiculata in
interfile soil. However, the ascorbic acid content was significantly decreased in B. oleraceae
by drought (Figure 2 and Table 4). For thiamine, the content was increased by drought in V.
unguiculata in both fertile and infertile soils and in B. oleraceae in infertile soil (Figure 2 and
Table 4).
Agriculture 2023, 13, x FOR PEER REVIEW 11 of 16 
 
 Infertile soil (S)       
Agriculture 2023, 13, x FOR PEER REVIEW 11 of 16 
   75% PC 11.3 189 101 3.0 15 27 
Agriculture 2023, 13, x AFOgrRic PulEtuErRe R20E2V3I, E1W3,  x AFOgrRic PulEtuErRe R20E2V3I, E1W3,  x FOR PEER REVIEW 11 of 16 11 of 16 11 of 16 
  Agriculture 2023, 13, x   AFOgrRi c PulEt5uE0rRe% R20 EP2V3CI, E1 W3,  x FOR PEER1 2R.E0V IEW 117 87 1.5 14 11 of 16 9 11 of 16 
  
Agriculture 2023, 13, x AFOgrRic PulEtuErRe R20E2V3I, E1W3,  x AF OgrRi c PulEt2uErR5e% R20E 2PV3CI, E1 W3,  x FOR PEER2 R0.E6V IEW 135 90 0.6 11 of 16 4 11 of 16 3 11 of 16 
    Infertile soil (S)       
Agriculture 2023, 13, x SFOolRa nPuEEmR  sRcEaVbrIEuWm       11 of 16  
 Infertile soil (S)   Infer tile soil (S)    I nfe7r5 ti%le  PsCoi l (S)    11.3   1 89    101    3.0   15  27 
 Infertile soil (S)   FInefretril teil eso siol i(lL ()S )                  
 Agr icult7u5re% 2 0P23C,  13, x  AFOgrR ic PulEt7uE5rR1e% 1R2. 0E3P2V 3CI, E 1W3,  x   FOR1  8 P9E7 5E50R1% 1R.  E3PV CIE  W 118091  112..30  3.0 11810971   153 .0 18071  217 53 1..05  11 of 162 17 54  11 of 162 97  
  Infertile soil (S)    I nfe7r5 ti%le  PsCoi l (S)     I  nfe77r55 t1i%1le.  3 PPs Coi  l (S)  1 89  21.19. 3   11 1580291     3.0  119001    15 03 ..70   2 317 75   4247  
  50% PC  Agri cult5u0r1e% 2.0 0P2 3C, 1 3, x  AF OgrR1i  c 1Pu7lEt5 2uE0rR51e% 2R.0 E 0P2V 3CI, E1  W3,  x FOR18 1P77E  ER12 2R0..E06V  IEW1 .5 1813775   141 .5 8970  91 41 0..56  91 44  11 of 16 93  11 of 16 
  75% PC      Inf7e5r501t%i1l.e  3P  sCo i l (S)     1   897 555001 %%12..   30PP  CC   1 1810971   131.24..3 0  3.0 1118 821079771     153 1 ..05  1280071 2  217  543 01 ...065   29 172  524   23975 Solanum scabrum         
  25% PC   252%0. 6P C  1 352 52%0. 6P C 19305  20.6 0.6 19305  4 0.6 90 34  0.6 34  3 
  50% PC     527051%2.  0P C     1   175 2205512%%201..   063PP  CC   181387759   1422.03..0 6  1.5 1189118370705  1    141 03..560  829730  7 91 44 51 00 ...546   9321 14 747   923 7  
SA ogrlaiIcnuulfteumrret  si2lc0ea2 bs3ro, u1i3lm ,( x S )SF  OolRaI nPuEfeEmrR  t  siRlceEa VbsrIoEuiWlm (  S)S  ol a Fneurmti l  esc saobirlu (mL)                          11 of 16       
   25% PC  S ol a nu25m502% 0sc.  6aP bCru  m   Sol1 aI3nn5fu2e mr52 1t% i0s2lc.e. 6a0P  sb Coru ilm (S ) 1 931057   2  0.6 0.6 1  9 83075   4 0 1..65  9  0 34  1 40  .6 3 94    3   
  F ert7i5le% s oPiCl  (L)    FI nefret7ri5l t1ei%1l es. 3o Ps iCol i (lL ()S )  1F8e9rt il 1e1 s.3o il (L)  1 18091    3.0   101  15 3 .0   2 17 5   2 7  
Solanum scabrum     F er2ti5le% s PoiCl  
  I nfe7r5ti%le  PsCoi l (S)  2.9  152  190  0.7  37  44 
Agriculture 2023, 13, x FOR PEER REVIE(WL )    Fer7ti5
 
Solanum scabrum Solanum l 2 e%s0c s. a6Pob iCrlu  
 
(mL)    1 35  4 .9   1
 
   9202  
 
   0.6  1 77  
   4  0 .5  
11 of 16   3 1 3  1 9 
    7550%  PC        77555021%.29.    0PP C      1   512777 5 5502%.29.    0PP C   1185197270    213.1.94. 3  01..75  1118582972970     31740 1 ..75  112900012   4934  7403  ...706   493142  752   423475   
 Fertile soil (L)   SolFa nerut7mi5l e %s cs aoPbiClr u (Lm)      F  ert57i0
1
5l 2 e%
1.
. 9s 
3
  oP
 
PiCl  
189 
 (L)  1 52  52..39   1
1
1 1 2
0
595
1
20 
 3.0 
      0 .7  115900 15 
  3 7 00 ..27 27
  4  5
 
 34  7  54 4 
    I nfe52r05t%ile  P sCoi  l (S)       5520053 2%.04.    6PP C      1    237555 2 00532%.04.   6PP C   12 9230752    314.2.43. 0  0 ..6  112921807702     2 42 0 ..6  28073 27  3 254  2 01 ...654   32151  247   3925 7  
  75% PC     Fer75t5i02l%e.9 s   PoCil   (L)    1   527 2555
1
023 %%
2.
..94  
0
   PP
 
CC  
117 
 1 5227  253...954   11
8
12 56
7
29026
 
702  
1.5 
190 0.7    370  ..76  112920082  
14 
 4342  720 0 ...716  
9 
 43 34125 7  2  4134 5  
  Sol  anu27m5% sc  aPbCru  m   Sol  anu22m5541 % .1s3c.   3aP bCru  m    1   I8n09f22e  r5542 t%i.03l.e   6P  sCo  il (S) 11 21 83300571    42 .03. 6 1 03 ..40  11 2 833057   1 750  .4 29 30 7 2 17  700  ..46  2 147  7  23 7  
   Infe5r0t%ile P sCoi l (S)     527053 %.4   PC    1  275 205342%..439   PC  122850702   34..43  RN0I.,6 r eco91m0 
1228039702m70    ended2 n2u
0
0 t
.
.r
6
.647i
 
 e nt 2in03t27a  ke; va3l
4
2u
 
513 2e70s   ..f64o  r female adu3
324lt
 
25174s 2  7( 1 9–50 years) (W32H57O   & FAO, 2004); 2 
   I Fnefre5tr0itl%eil es P osCioli (lL (S) ) S  olaIFnnefuremtri 1tl  eis2lc e.sa0 osb iorlu i(lmL (S)  ) S    ol1a I n1n7fue 7mr5  t  i%slce a PsbCorui l (S)     
 
m 8 7   4.9  
RAE 1 ,. 5r etin  1   o2l2 a 
 
ctivity  1 e4q   uivale  n17t,7 b 
 
iocon 9 v   er  s0i.o5n  of ingested    β  1-3c arotene to retino  1l9 b ased on equiva-
    275%  PC     I nf2e5r5041t%i.13l.e   3P  sCo i l (S)   1 I8n0f2e r54 3t%i..3l4e   P sCo il (S) 1 282307   4 .3 0.4 1 2 830072   170  ..46  2 37 217 2 720  .4 2 317 5 7  2 7 
    75%  PC      F er7ti5l4e%.. 9s    PoiCl   (L)   1  25297  5 504 2%..9   PC  11 1257
092710      2   20.6  F3e5r tile soil (L) 90  4 5..93  lenc03y... 507fa  .6  ct1 o1 2r79s257,0    f or whi1c3h3570 4     1.. 57μ  g R1 A75E70   = 12 μ14g1 934  
 
3 3β 70  - c..5a2 r otene (WHO1 4 &1 954 3   F AO, 2004). 1 59  
  I nfe5r0t%ile P sCoi l (S)   I nfe72r5 1ti%2le. 0 Ps Coi l (S)    I nfe7r5 t4i%.l93e   PsCoi l (S)  1 2820  4.9   1 1227327    0.54  177   137 0 .5  12 197 3  19 
    50%  PC        570553%..34     PPC     11  21575  Solanum scabrum     772 05523%...394      PPC   181122
7
550527
 
 02     52...395   01...256    11112256590526002      512 420  0 ...276   11592008   5935  3 2 7 200  ...271   54353 41  7   541 4  
    725%  PC      Inf7e5r5042t%i.09l.e  6P  sCo i l (S)   1  23257  55045 %..93   PC  1 1927025 7   45..93  0.5 11 1 2752570    130  ..52  17570  1195  3 0 ..52  15 195  3  159  
    F er2ti5le% s  PoiCl   (L)       25505 4%..53     PPC     1   686025  50534%...543     PPC  111 26282367087     53..54  3R.5N.0  EI.
..,164 ffr   ecto1112sm62 203o6782m7f      Denrdouedg14  hn 
 t7u 00 ut...rn164id  e nert 12Tin20wt82ao  k Se;o vila 13 2Fl12u 
 7e 2er 7t00s  i ..lf16iot  rie fse mona lFer aesdhu 132lYt12 57si  2 e (l 1d9 a–n50d  yVeiatarsm) i(nW C13H 5oO nt &en FtsA O, 2004); 2 
 Sola nu5m0 %sc aPbCru m     52705 %.3   P   
1C   1   255 2054%..359    PC  11 2655620   5..35  112652756087    0..215  15208  51  30 ..21  515 1 9  51  
   Inf7er5t%ile P sCo il (S)    Inf2er52 t%i.9le  P sCoR iNl I(,S r) e co1  m52me4 n.d3e d1 R nNutIr, ireencto1   im
RAE 
8n0tma keen;d vead1l 
0.2 5 5 
Ru neNus tI ,fr, T oirreaeren btcfitoeln 2e im
onl activity 
3 4tam7a l sekh enao;d vweuadlsltu  s na
e eq(u suivalent, biocon 
01t u9.fr4oi–me r5n 0mfte  yimanertayarlek so )ea f;(d  WvtuhalH let
vuersion of ingested
1s Od e7(s 1 r& o9fo– uFr5gA 0fhe Oymte’, sa2 rl0ees0ff )a4 e(d)Wc; ut2  2lH 
 otβ-carotene to retinol based on equiva-
2 5% PC 190 4.3 0.7 180 37 
  50   .3 1 237 44 0.4 17sOn  7(  1 t&9h– eF5 Af0r Oeyse, ha2r0 ys0)i4 e()Wl;d 2 2H a7On d & v FiAtaOm, i2n0 0c4o)n; -2 
   Fer2ti5le% s PoiCl  (L)   255 %.5  PRCA E, r etin1  o6l6 a2 c55t%i.v5 i PtyRC RAe qNEu,I i,r vreaetlcieno1n1 om62tl6,5 8 ma b  cie5toni.cv5doi etnyRdl
1
ve
 
 R AenqNrEcus0 uy,tIi. ori, 1r vfinrea eae tnclcoitent1of n1 oim6rin2t5lsn6, t8 m,0aga b f ckeoietosenritcv ;dew oivdetnahyd vlβi 1 u cen-h eqrcus0s au1ti .r.ofri 12ovμoin e targ en lo fnetRef n1e imAin 2tnt,Et8a ogabl  ek=eiro se ea1ct;de2 iovnd unμao1  lvlβgtl1u 5 se -b  eβrc(as0s-1i sc.r9of1eaoo–nd rtr5o e  0fonte fney mni enteeao qgr(l euWesr )seia vtH(deiaWnduO-o1 5lH βtl&1   s-Ob  c (Fa 1&Asr9eo– OdFt5eA ,0 on2 Oney0 e,0te a42oqr)0 us.r0 )ei4 vt()iaW;n 
2 
-o1Hl O & FAO, 2004); 2 
    5705%  PC    I nfe7r53t4i%..l49e   PsCoi l (S)  1In27f2e  r t4i.l9e  sRoAilE (,S r)e tin 121o207l2 7a   c tents of th ree green le afy vegetables  under two differ ent soil fertility con bdaisteiodn osn.  Feoqur itvhae-  
l1e RnNcyI,  fraecctomrsm, foenr dwehdl1ei R cnhNcu y1tIr,  μfiraeegncc ttRo imArnsEtm, af k=oe etnr1i ;dvw2 vi eμtahdyl1Rlgei Ru  cnA eheβNcquE
0
s -y1utI c,
..
fr,  
6
ai
5
 μfoirv
 
raree
 
regaonc tc fltitReoen
 
 n
1
imnAro
7
nstelEt,am, 
7  aa(lf b
 
ek=Woci  etnora1iH ;cvdw2 voi euOμtahndyll gitv&u  
21
csn e
23
h eβ q(urFs -s
0 
1utA c9i
.
fr aoi
5
μoi–Ovren
 
r5gaon , 0 fltot2Ree  f
 
y0nimnA ne0itenEta,4  ar(gl) bek=Ws.e i ) eosa1 H;(tcd2 Wevo uOdμan
31
lH l gtv&β
519
us Oe-
  3    25% PC 5.5 166 128 0.1 1 eβ  (rcFs -1sa&A c9ifraoo– oOrFnr5toA , e0 fto2ne Ofy0men e,0i e nta42 or(gl)0eW s.e0 r )sa4e H(td)Wei;n uOd2 o1lH1  t&βl
 9
s  O- b
 
 (cF 1a&A9sre– oOFd5tA,e0  2on Oy0nee,0  tae42oqr)0 s.u0 r)4e i(vt)Wi;an 2- o   75% PC 2.9 152 190 0.7 37 44 Hl Ob a&se FdA oOn,  e2q0u04iv);a 2- 
    2550%  PC      755045%..3   P  
RCA E, r etin1 o82l05 a7  c545t%.3i.v9  i PtyRl1Ce  Aen qEcuy, i rvfeaatcliten1on21o2r35tls25, 7 ,0a    f o4r. 9w hfleircnehsc0 yh1.. 4 2μfya  gice tR1lbcitoicvoitnyRv AeqrEsu,i oirvnea tloienofn1
d
 oA2r5i7s
,2 nE7,0
t
g   f
h  =oe r1  tw2h μhregi1c5e h7β  ested β-c0
g  a-1c.
r.
r 5a2μ
e
o r egon tRe 1lnAe7eaE7 f(  =Wy  1vH2e Oμg25 getene to retinol&175 
t
 b RNI, recommended nutri n  int ke; value  f r femal  adults 3
a
 β
  (Fa0 -
bles were sign
1Asc.95ea–Od r5o ,0 ot2e ny0n e0eea4 
5 
qr()uWs. )i vH(aWO-1
ifi
H &19
c
O 3 
aF ntly decreased by drought (Fig-
tl,  abcitoicvoitnyv eqrsuioivna loefn itn, gbeiosceodn vβe-rcsiroont enfe intog erseteindo βl -bca &Asreo OdFteA , on2One0 ,0te 42oq)0 u.r0 ei4vt)ia;n -2o1 l9 b  ased on equiva-
   5205%%  PPCC      5205
35.
%.
45  
  PC  
112676  5..35  
202 3.5.0 E.6ff ects of Dr ug2h2t  nd r Two Soil 3F5 t liti s o  Fresh Yield and Vitamin Contents 
 Infertile soil (S)     50% PlRCenA cEy, fraecttion1 1ro26s2l56, 8  
ure 1 and
a  c5ti.v3i ty eq 0u.i1v al 112 52Tt508 
a
b  
ble 4). T
ioconv 1e r0
h
si..o21
e
n  
 β-carotene c
 of1 5in0g ested 1β51 
o
-  
ntent was sign
c0a.r2o tene to retino51
ifi
l5  
cantly increased in S. scabrum in 
3le.n5c. yE fffaeccttosr so,f  fDorr owuhg3ih.c5ht.   u1En μffdegec rRt sTA owEf of D=o S r1r ow2iu lμh g3lFgeih.cen 5htβrc. t  -uy1iEcln aiμffftdariegocec trsRtoe sTonAr snoweE,f   (oFf D=Wo rS re1rH osw2ihu Olμh gFY gi&hcei hteβr  Flt -ud1iAcln  aiμaOtdrnigoe,d trs2Re 0VTonA0nweiE4t  a(oF) =W.m  rS e1iHos2nih Ol μ CFY g&oei neβr Flt-diAcel aniaOtrtniose,d t s2e 0Von0nei4t  a(F)W.m reiHsnhO  CY &oi ne b FltadAes neaOtdns,d  2o 0Vn0 ie4taq).mu iivna -C5o   25% PC 4.3 ntents 
  25% P1C R NI, reco1m80m e5n.5d ed3 237 0.T4a ble 4 sh ws 1a7 s ummary of th2e7 d rought’s effect o  the fresh yield a d vitamin con-
  75% PC 4.9  1 222 5% Pl1Ce R .n5 Ncu. yEtIr,  fffiraeencctto1o 1sim6r n7so6t7m,fa   fDkoe5enrr. ;5dow v ueahdgf3lieu h.cn5rhtetu. 0s  iu1Et l.frne 5μoffi d esregne oc frRte1i 1slTimA6, n2 ow6wEt8afa  lo Dehk=  S eia1rl;od2e viu  lμta ghlFlgt1uhsee 3t eβr ( ct0s -1uio c.9lfn1aino–td rri5toe e0ftrsnee  1yTmont2e nwewa8  r(lo FaeWs r S)sae  Ho(sdsWihiuOlg 1lHFY nt&19seiOi  erfi (Flt0 1dci&A.9l a1ia– Ot nFni5Ae,t0d sl2 Oy y0Vo e,0nd ia42t earF)0cs.m0 r)r4e ei(s)nWa;h  s2 C1 HYe1 odiO ne lbt d&ey na  FtdnsAdr oO Vu, ig2ta0hm0t4 ii)nn;   2CV1  o. nutnegnutsic ulata and 
 Infertile soil (S)  RAE,T raebtiln eo 4l  aschtoivwitysR  aAe qEsuu,T mabmle a r4y s hofo wthset e adn srt souT umoagfbm hltehta’ rr4sey es ffho gfoe rcwtehte seon  and  l sretouhauemfy gfm rhvetaes’grshy e y tffoaifeb lctldhet  seoa  und ndrtohd vuei grtfa rhtmewts’sihon e   ydffciioeffnlcdet-r  oaen tdt hs voeii tfla rfmeesrihtni l yciitoeynl dc-o annddi tvioitnasm. Fino rc othne-  
  50% PC 5.3 3.5. Effect1s2 o5f Droug31 Rh.5tN.  uEI,nTi ffrvrdaeeaebtclriteoln s1enTmo 5 otw4l,m0 f  a ob sDec ihStnoriocdviwouieltn dgy31F
S
s vR h . e
.n5 aetrNqur
s.  t 0sus
cuiEtIuil.
ar,nTo2ii ffi
bvrmtdena ie
rane bc
u
mlrosteo
m
l sfenTioma  n in
 otwr4nt,
imf  ya
n
  goFbsDk e 
 eihroSe
inosernf;otcds 
f
 eviwothuel
edhan dg
rFYs l
t
evβu h 5e ni
i
aedt-er 
lurc  
eltsrusdait 
 
ouilfrnr 
soioaiumt
odennritigne  ed
l
mfrost
 
hne f
(VTimoeFta n’in wi
i
rsnttat 
g
yo agloFeek 
u
 m effrro Sesae
refie;o
estd n eicvith
 nul d2hta C o5lFY l
 
eotβuol s
ae i dn- erb
n(cl st1ratd
di eo9hlsfr ni
 oea–ouet
Ttdnri5t gs
ae ef0 df s
b
rhone  eyVnmoe
le
tse’n ishtae
 t o4 aqrlFe e ys
)muffrr )
. 
iaee iei(v
TstdnWlichan
h
du t- C olHY
e
 otaol
 si Oan eb(ls t 1atd&
ce9hs  n
o
vea– eFt
rdni5 sA
b
tf0 da 
i
ro O 
c
meyVn
 
se,  i
a
ihae2t
c
naqr0
i
  ysmu0
d
c)i4 ioei
 (v)nWcl;ad  
o
-2-C H
n
 ao
tOnedt 
n&et n
 w
v FtisAta 
aOs signifi-
m, i2n0 0c4o)n; -2 
  75% PC 4.9 tleennctsy  ofafc tt1oh2rrs2e, ef ogr rweeht3lneei.cn n5hlc.te  sy1Ea  foμfffyafegc c vttRtoh1esArr 7gsoeE7,ef e  ft agbrleeest
fne ru nelnsD=o r1r ow2u μhggihc htβte 0 -s
h1dac. n 5a
 feoμyrfi evtlhwedrg,oe et ehdt aegibff rtlehersrdrgoe trRe TnAwE (o =W S 1Ho2 Olμ Fen  g&1un
e  3βl tn eFgt  -dsaAc
rofeyirel  nvtfw elregotaei fldtiyati ybffv lecrglaiOtrioe, ts2e 0on0e4 (WHOos1e  en&9untd a tnF ibdsAtlioeoOirsnl,    twsf2we.0 erF0otr4oi el)dr i.s t ityiffhg ecnero iefinncdta isntiotolinyl  sfde. erFtcoirlreit atyhs cedo n bdyi tdioronus.g Fhot r( Ftihge- 
  25% PC 5.5 166 tents of th12re8e  greeRtneA nlEte0s,a.  1rfoe yft ivtnheorgl eatc atgibvrlieeteysn  1u  qlneudaivfyarl evtwnetg,o  b F
).i dtaroiebffcsolehnr s1Yve  euiertnls didso oaninr l od tff we Virnoittgi aldeimtsiyffien edc rCo eβno-ndctt iesrtnioootiensl n sfee. rFttooi lrrit etythi nceoo ln bdaisteiodn osn.  Feoqur itvhae-  
  50% PC 5.3 freshT yaibelled ,4 t shheo tw
RAE, Traebtihrsfer ae  sgshur eymeienml
n
l e
o
dlae ,r4
l 
 ayt 
a
fs
c
h yho
ti
e fo
v
 vt wt
ityc
ehhgrs
 a
feer  a
enqt
etda  sgsr
ul
bhourlT
iyv 
 ueyma
ai
esgibe nm
lnhe
c
wll e
nr
dtlae’ 
te
,r4s
, a
r ay 
bs
teefsh 
i
 yffho
oe
se ifoe
cd
 vgt cw
o tehnht
nin
gr iseo
v 
fie  a
eS
entd
r.
ca  a gsr
s tbnouh
isoc
rltueem
na
les yg
 bf nm
orr h
fu
wd etla
 
es’
imrsnhrcay 
g 
ere fy 
e
e yffo
su
sai ife
t
vgs 
eri
lctd
n
endhtgd 
 
i eo
βg
fiea  btnd
- c
caya drt
ar
b noh
rou
d lvtuee
t
rliso ygt
egf aur h
nh
wdme
et
gtes’
 ,
hsih
t or
rcn tere 
 e
  ye (ffc
rg
sFai
eoie
ta
igsngl
icn
rd
endt--d 
o
i ofia
ll e
 bn
bs
cya d
ast nh
s 
d v
e
te
df 
rlio ytf
 taur
oh
 dme
ne
ges
 
hih
e s
cn
qo
tr   y
ui
e(cFai
iloev
 c
isngl
ao
ed-
- ndition, and in V. 
-d a bnyd d vriotaumghint  (cFoing-
1 125 lency facto1r5s,0 f 
ure
or whuicnhg 0
 1
1u. i2
 
μc 
a  Table 4)
gu lRatAaE i n=  i1n2t eμrgfi5
.  Th  β-carotene5 cont nt was si nificantly incr s  in S. scabrum in 
RNI, recommendedfr neushtrT ieainbetl din ,4t at shkheo ; tvwharlsfleru aeec sgyh ufr fomareic enmfteol dmlraes,ra ,y tlffhe oyo era f  vdwt thuhhgrlitecs  ethd β
le
a(  g-1rb1c
 s
o9r a
o
lμ–ur5geso
il
g0 n t
.
hwRe
 H
  ytnAle’e
o
srEa er(
w ef=W
e
s yffs) 1 iH
e
ev(g2Wc nOμ
r
tg iH g
,
ofie&
 t hOtcβ aF
e
a  -tb&Ac
 a
nhal tOr
s
Flso yA,
c
f  tr w2
oeOd0n
r
es,0
be hrc4
i
2 er()
c
0 Wy.
 
e 0 
acid content was significantly decreased-  
ute
sa4i
rnet s1  oafn tdh rTeaeb glere 4eut)ne.r  nelTte sh1a e foya fβn vt-dhce ragTereaeotb atgelbernle ee4es ut)nec .ru o nelTnnte shd1at e feonya rfβnt v t-dhwwce ragoTaeresa eodt b atsgielbifferngl een4ers i)enc fi.un o clTtnnea hdsatneofetny lirylβt  vt f-wwiecnargoactreis roldt eiatstiaeybiffsng leecendros iec fi nuniocdntnna  idstntSeioeto.nl irnylst  cts fwwaie. nbrFoarctoisu rld reimst iatyiffe
Hgs)l;n shgi eenced
 O2d i  fia& bnc yFad And vtOrloyt, au 2dm0ge0hic4ntr)  .e( cFaoisng-d by drought (Fig-
  25% PC 5.5 3.5. Effects of Droug3h.5t.  uEnffdeecrt sT owf D Sroiul gFhetr tuilnitdiers Ton F rSeosihl FYeierltdil iatnieds Vonit aFmr isnh CYoeltde ntnd Vita in droC  iefi nonicdnta t isnteSionto.l itnyls cs faie. nbrFrctoiurlreimt aty shi encedo   nidn itSio. nscsa. bFrourm t hine  
RAE, retin1o6l6 a ctivity in B. oleraceae by dr ught (Figure 2 and Table 4). For thiamine, the content was increased 
u
fferertsihle y sioelidl, ,w thhei lteh trffhte
 
ere
er
eern
eq
  tscgt
 u
ihos
1iv 
lre neyo
a
 setif
l
eoen 
etnli h
n1d 2t
llt,er
,T8
 ,w ae
 tba
 fert
fheib
ahy e
o
sig 
l vcel tr
o n4
seehi ggtre
uv)
ffhnen
.re er
ereetria fi l
T
tscge
s0
il
 i1.
ibhcolar
o1
 
 
ela neyf
n 
soil, while th1e  content was sig1n ifica tly decreased by drought in V. unguiculata and 
ya  βov-fc  iagnTrgaoteb nsestietoe nwlnliy dllte,  d,rw ateefhah cysae
tsel
sri i vb
tene
le gtseaehln
 de4
i gsgtris
  )βc
henfie 
.
deeut
 -ocTnah
ica fi  acgbbcondr
tront 
ylante nldestyr
eβt
et nr  w
n 
lt
-wec at
ndoy ltue  drcwoa
ros
geer f
o 
haed 
 rtseei
cystsar i ve ff
tnginen
igssnaeni gsgdr
o ilcfi 
Vienfie .bdtn
obc
 icuafiy at
nas
bbn cnds
tne
ylgatoer
tdnl
 unldsoiy
y
il
 to 
t rcu wldof
nwi
yuge
n 
ue lrh
eac
darcgt
q
tteeri
sr
ah le 
 u
c( is
s
tFaart
ii y
ivsa
eiignsnga endc
n-- sdVio
ifi 
 efi .nb
ic
d cudy
na 
 abn ind
n
yt
S
gitr
t
 uo
.ll doyn
ysc
ircu s
 daioug.uel 
nbhaFc
rc
gttor
ur
ah e(r
m
 tFaa  t
 s
iinsh
in
ngede-
  in S. scabrum in 
l1e RnNcyI, T fraecbctolemr s4m, fsoehnro dwwehdsfie rc
na  dV  .b uyn dgruoicuuglhatta ( Faingd-3.5. Effects of Drougbhyt  durnoduerg hTwt ion S Vo.i lu Fegrutiilciutileast ao nin F breosthh Y feierltdi laen adn Vdi tianmfeirnt iCleo nsoteinlst sa nd in B. oleraceae in infertile  
Su.r es c1a barnumd  Tina bilnef e4rSu)t..ri  e
rhu ts si1
tlur Tμieym ags
n
iboe mRl
 i
liedlAa
n,  ,r4Ew
ta
 yt  s
k
h= hho 
ei1fo; l2
 v
tewth  hμ
at3
Sl
rsfhege
u..  e 5arde
s
β . tsc 
c
g-ri
E colouf
b
ra
ffneumr 
rersetog
 cueof
m
nmth
tenism
 
 ltnat
 ,oe’ ersw
aifn
a y
 (leDe
 
fW ah
 iarn
yffosi fHe
dfuer
vl  sectiO htgt
g lhe ot
t
ne&
hsi ent 
l
tid 
( e
a fiF c
1ru
 
tbAcoo
9hn
s–o
lanO
d5i
eest g,fet
0l 
  
rrhw2l
 nyey
(F
0Ttte
i
es ’0
w dsha
g
w4 ero)e ys
u
a.  cff 
S)rsri eoe (
e
sWlci
 
aidl
2
tgs HF
 a
 eonadOnir
n
fi  t 
d
bti&chl yai
 
v et
T
 Fiid A
a
teftars
b
rlOo
le,n  2 4F0)0r.4 Ts);hh 2  Y iaelsdc oarnbdi cV itcaimdi nc oCnotnet tn wts as signifi-
RAE, retinol activity equivalent, bioconcverstiloyn i nofc rienagseestde in
doymeues dihgne h ycctrio eeinlad- sV ea.bd uy bn d ygvr uidotiarcuoumgulhaigntah  (c tFo inngd-leTse ch 1ase boa riβnul -md(cF a Tirgnaou btierlneenf  ee42r Su) ct.a.ri o lenTsen cdh 1tas e boTna riaβnutlb  -md(wclFe a Tai rgn4saou ) bt.sier lniTeengf  heen42r ei) ctfi .ai oalcnTesnadhc tnso etoTrn liabyβtlb i -c(wiclFn eaaai crg4csroiu )edt.saer i Tesngce heno2d eni cfi  atioaecnnsnand ctntSo e tT.wrnl abystabci cswailn ebasa rci4csurgi )emdn.sa i i Tsgficiehno-de nifi  tiaecnsan cntSo t.wrl bysaci csain basrcicurgiemdna i sficieno--
 d V . unguiculata and 
tents of three greeSutne. n elste cs1aa  fboyarfnu vtmdhe r gTeienaet b aig
n tienn tS .w sacsa bsriugmni fiin- 
cfearnttilley  sioniclr, ewasheilde  itncfhea eSrn tc.ti ollse
T
ycn 
a
 ast
b
ibeo
l
nrni
e
culrt,
 4 s
m ewa dash
h
esui
old sre
w
 ii ingt
sslnbrfle ee4esrS)nt .ui  llTsneecncfhnge
 o
a e
ai
S rind fi
 ltcs
 
.ti rcol
u(F
lsoeyacn
mig un astibegto
muh dasefbeoy rriβu lvt -mw(ceFa goirgen odtu atiiernbffnfl e
 β -Sc.a srocatenrue mto  dreutrininogl  bdarsedu gohnt ,e qreugivaar-dless of the soil dition, and in V. 
Table 4 showe2rssr  e ct aauinoln tnens d udsts eomeoTirialmt l bt fw(welaFerroai tyg4is l du )oi.tir fyffTe gt  ehhcn2roei efi  adacndtsra diosnto iuotTorliganbyl hbis fctie.l n’ ersF ct o4cierli)reffid.t  ty Tshcc ehcetod o non tiaedn st ichttSoi eo.wr  nbfsracisecsa.s  bFhsriocu gyirmdni et ihlficidneo-   natned tv witaams isnig cnoinfi--
3lfer.n5ec.s yhE  fffyaeiccettolsd so, ,f t fhDoerr  owthuhrgicffeerh
ch nlrnihcyul
are
rt,t m d
r 
e,w
y2  
 are deashc
oa
egsrui
fnlde 
 
asre
tda rii 
h 
ingstdnh
eTen 
a
gl deeS i
db
d sfi c
rl
.bs rco
oe
s yaocn
u 4 unafdt
g)
 begtr
h. 
tlrnhoy
t
uteut 
’
m d
s
, wg
 
 sre
e
 hodeac
ff
itgsr
e
ul e  ias
c
rcnarii
t
o ngs
 
dVne
ongl.d
n
ed  iudsfi 
 
ib
t
stnrc
h
i yga
e
o uunnfd
 f
 igt,r
r
tc lhoayu
e
enu
s
t lda
h
, dg stre
 ahyo eci itngar
i
l 
eeina cn
l
Va
d
rdo sd.V 
 
 ne
a
l.ded 
nus 
d
ibstn
 
i yg
v
o uinfd
t
 i
a
,rtc hoau
m
enula
i
 dg
n
stah
 c
o i itna
o
l in
n
 cnVd
-
o .V  n.d uitnigouni,c aunladta i nan Vd.  
uSn. gscuaibcurulamta  iinn  iinnfteer ae
ruS
tetfin.i
n r
t
ln
  tsgu
1
tihlrn
 μ
lgse
t
ec
s
u  a
 
ssie
y boey
dg
oco 
 
urs
efiie
 
iilu
 lonen
rtRl
l. a mi
 hc(d
TAllr,rew
E
HtFa  
,ee
oi w
 atao
 fh=shy Se
 1
ei  vldo
2teieh
 
 l
μ
 igt 
un
rtnFchee eeent
β
Sr
g
a  tt
-u
.gtb si
c
olslr 
ailyi
c
conet
r
 ai
u
efsotie
lt
ben ns
a
twe
t
rnhc uo
na 
lrternm eer
 
wa 
i
aee
(
 F
n
fW
 in
das y rsgesue i
Ht
vd rgssrehe
Oer
 niiengg niY
 n&
fi
ngfie i
l
 tS icel
 aFdfil
e
ea.db
A so
 rans lafcat
Oi
eyunalnsy
,l
gtd 
 .v w2
 
lrd 
H0
hyueV
0o
te gmdi
4
,rc t
w
eerear
)
 t
.
ee cma
 ever, the ascorbic acid conte t was significantly decreased 
sgaubiigsanrlaerni nign
e
wnu 
 
 i
g
eirn
r
nvef
e
t ee
e
e2rrruS 
n
,tfi an.ti
  llhlngse
e
ecedu 
a
 as s
f
i abocoT
y
suriiaclu
 lvl.bo a m(
e
HltrFeab 
g
oi  ig
en4t
wcnu) 
a
  a.ieir n
b
ncvTeif
l
t 
e
ehdee2
s
rrer  ,ct
 
fi  a
u
tioalhln
n
neesedc 
d
 ts seo 
e
aooT
r
nrsiiab
 
ctll. b
t
o i
w
w c(HlrF e
o
abaoi sig4c
 d
wc siu) da.
i
ier 
ff
gc vTecni 
e
ehdoi2
r
rs
ddCsie gfil oubde ncdsyn atbs rden ynoetr utlfdroys  grt ut hdowguteho, cg st rrfie n 
e
,c  a
n
cttoaeahn
t
nsn
 
nedc
s
tt teo 
o
a lTnwyr
i
sab
l 
ct da boi
f
wcs
e
elr e
r
acbas 
t
rsii4c
il
ec gh
do ee(i
si)
i
 adna.
t
it
Figa ylff iisangeer- rddVel .nbed usyti stn sid goorunifol i, tcu fhauegenlrh tdsittlao  i(i tiFnaylin  gVcd-.o nddiittiioonn, sa. nFdo ri nth Ve. i  B. oleraceae by dr ught (Figure 2 nd Tabl  4). Fsgco iTefic
 
nirdh
co-o itfie n
n
ch ctoaie
d
ansn
i
nmc
t
ttteo
i olinwyr
nbt eda i
s
w,cs
. 
e t 
F
achasrsi
oce gsi
r
adn
 t
 cisgo i
h
efic
e
ndo-
 
Table 4. Comp r son of ffects f increasi g drought in two soil fertility co itfii neticntoeatnn nwstt  l(awyfse d aritsnei lccesrr,i egLan ssaiefind-  
 
ure 1  
T aabnlde  4T ashbloew 4su
icna nBt.l yo lienraccreeaaes ebdy  idnic
fSu)r .an.a
re  en 
Tgsss thclu
1ay i
ey m
rn oS Bu. .gs ochb
ca  aultr
βn
iieb n
eumlla-r(racm
dcta aa
Fucr 
,rT 
imee
 iyrtiano gaa
h
u eds 
boet ielfne nt
 re
 
bued
tfht hee4f ru)rcy r2  ii
r
dn naic
egrta
fi .n
n 
e
oiS 
d olTgsenrhuo ts ieuyocn ugii
 n
 
ddBu.
gt  r.gls
r
T oyoc
e
hau a
e
ltbiebi
β
gel
tlh.  la- d(HwtctF’aa,sao i r tigsewhnou ffet seiere nivtengchteetne2rr  rio ,cfifi aentochln  egnated hrtns  eaotTnesl iafycnltr.bo   eHwillrsnebhaoaci4s fwrcy )e a.sie a evicvTsglieedehngdr e iea,cfi  ttnoiaachnndabe ct nlS veaet.irssl tbycts aw co n
n
rl(raehc
 
Fu
l
c rt
e
i4mee,
a
g a)aru 
f
.e des
y
 rFebgu
 v
eodya r
e
r2 r i idn
g
 dtnahg
e
rln e
t
oiS 
a
addsu.
b
ms  rgs
l
T oc
e
hiaunaf
s
tb bg
 w
e tl(r,heF u
e
 teti4mh,
r
g  
e
)seru .od e
 s
rFcigu
ig
elo a rncr2r
nio tn d
i
taenhg
filnedi 
c
atddsi
a
 mstw r
niT o
t
iau
l
nnf
y
sb ge, t
 
l i,hi
 dm
ean c
airn
 tent
e babic4h, a
rcrcdnsier )ser
rcurc  sec mse.o  e
e
aiFcidng
aiaaoigcg sniined-iifi  fic c
sl
s
oa enc
e
rVrdo td
d.te  nhl
 b
nedit
oci
ate
ansyiann
 ntStet
 mst
 
wi
d o lr
.l
iannw
y foyt
s d 
s e, t
u a 
cdw
i,ha
g
n s
aee
ten 
bahc
ch s
crdrsrs
t
ei
rue 
eo 
 ges(maiasg aici
Fnsl
i
oi
s  eenc
gfiniVed
n
do
-
i fertile soil, S) n fresh yield and vitami  content (mg/100 g FW) of V. unguicut-
di.fi 
  bcayn dtlryo udgehcrte (aFsiegd-3.5. Eff cts of Drought under Two Soil Fbeyr tdilrotiueg hont  iFnr Vs.hu Yngeldic u atV itnamb i thC foenrteile sa nd infertile soils and i  B. oe l naentdrati, ct wBieo.a neos l, ie inrana nicnedraef eai,nr sat einVldde.
 
   
Agriculture 2023, 13, 984 ut
feenn
rttisl eo sf otihl,guiculatar
 
 e
w
ie
h
n  ig
il
nr
e
te
 
ee
t
ruuic
fhnefia
e
nr 
r elnl
 
gB
t
ee
c ut
i
 1.a
olls 
e
iy fo
n 
ocya l
st
uiieln 
eonlr.v
n
a da
icHte
lcrt ,age
 Two iaeawnet
ashb a eib
sliblnved
 yselt ee 
i 
e4id
gt
rsrubun
ih)n, rfi .yn 
ruet oS
i he
 fi
lTgBnu
c
 ed.
 eu h
c
 d1.
og a onhan
rs ia
e
oocs
 alur
tten
ui
βclb 
et lrt(
l
g.oar
- d
nawyHFchutr
ct  aaibtm
e doTog
w
 raa 
eu
 iiwcn
o edabc  t raeiib
serulenffve
e ny srt 2e
a
e ie
i
e4dn r
gs
r ra)e
en
,cgrfi .tn
d o ihlTd
fiteu
 nbe h  r
cstgsT
ya
 eaooha
 nus i
d
itblβcltg
t  r.l o(
lf- e
ohyHwFecr 1
ut arib4
da1o,gtr
g i)iswr
euoc.l
h  ef i
ctrFast
t
ee
r1eyi co
ei
v5nag  
nr2a
by drought in V. ubnyg udircouulagtah ti nin b Vo.t hu nfegruticleu laantad i inn bf eVocr.tit dhuil  necfe ogsrunotiticeleusn lata ntwad ai snin  sbf iBegor.nti tedr
cen   s
hoiird
ot Vaehcn
lfi  
i
e,c
fi
fl
.d
 cret oe
oi cdu
saahrs
 
nna
bm
octnes
in ttnTei  
y
tee
gi
laao
itao nu
elsneys
lfdbny  act  
tier
id t
cls,
no
 wh
ouwei.   t r
n
die
ul
acb4Fha
a cg)on rsiis
tsr.ah
fnec eos
 r e aFc
 s tt
f ai
a
rBesgl
oi 
tc
s
r 
ihnegi.nic
nreedn
 ltdoeio
 it
 dt Vei 
lfi  n
hfin.
ec
 cr od
ii cut
saa
nnoi
a m
cn
 tnwtniS
g
eitelaol
ita.u
sneyn
l syie
  at
s i,d
 c cn 
 wi,a
uanei ntb din
l
acch
arc
n rds
rtura
ifne e s
 emaic
 
 irBn
asgso s
n
te i.n
i
 lV
eddntdoei.
e   nint  wSa. ss cianbcrrums in  
lfi 
 
S. scabr m.  ecraacnetaley  idne icnrfeearsteilde  
fSr.e sshcaT ybaribeullmed  ,4 it nsh heion twfhersr a
buStyn.ei l
  g seg
su
dcu rasie
m
obcoeruinu
mllg m (
a
htFe
r
a tai
y
 ignif
 
nyu 
o
  ii r
f
Vnv
 t
ne.fe
h
t  eeug2fr
eso
rbn et
 
fiaytigr
dillaln te
r 
edibdl 
o(F
i rsel
ui
cs eou oTs
gg
uiliao 
hu
lalwg.b it (Hl
tr
ahle,F
’ees
 
 tr
 2
ioi  nge
e 
i4wnh 
ffa
 u)s. iir 
en
VlgvTee
cd
.tn e  h
t
hut2
  
rihe
oTa
 nfi ,f  ae
nb
etgcah nra
 cst
l
tedonc
he
ic lo nt
e 4
euTlrst
 
 y
f)
labae
r. 
ca bnonid
e
tcalrdte
s e  
h
baicw  inr4c
 y
ncae i) bfda.sa
i e c sTrs
lctieti
dhdhogid
 
le n
a
ec f b
n
et oiasefiy
d
rnsont cctd
 
ita
v
eol ersnw
irot bat
a
tula niwy
mcgsd  ahd
iasn siteicn 
 
 gcsi(
c
f dnFir
o
Bege i
n
r.gfica
-
 too-is-lfienedcrt se obcneiyttl ls ewyd  airdanose du ins giifnhge tnrB tiii.nfi loe -Vl e.r uacnegue iicnu liantfae artnilde  
sino iBl .( Foilgeruarcee a2e  abnyd d si
f
Trn
er
oao ibBu
ti
l l.
l
(ge 
e
Foh
 
 i4l
stge
o
) ru.(a
il
 Frc
,i eeg
w
 a2ue
h
  rab
ielny 
e2d 
 d t asi
h
Tr
e
onao 
 
idbBu
c
l  l.
o
(gTe Fo
nh ai4l
ttbge
e
) rlu.(
nae Frc 
tie4e
 gw a)2u.e 
a
  rFab
seo ny 
sr2d 
i d gt a
n
Thrnaoi
iadfibum 
c
lgT
a
ehi a
nn4tb
t
)e l.(
l,ey F  t
 i4hdg)eeu. crFcreoe nr2a t staeehndiatd  bmw Tyia ndsbe rli,eon  tuc4hgr)ee.h aFctso iennrd t tVe hn.i aut mnwgiaunsie ci,un tlcharteea ac asonenddte  nt was increased 
bu
tcearnent ts1l y oa fin ntdhcr rTeaaesb geledre  4iensic)
n l
noa S niT
e
Bl.t  h
a
.(ls Fye
fcy i algieβb
 nvrur-accu
e
rcra
g
emer
e
 aa2o 
ta
eds  taebeu
bdnles
yrd  iidn  SnsTc
 gro. 
u
aoS isd
n
bnl.c
d
  lr(tgaseoFecb
e
h nui4ar
r
tgubt
 t
)g u.(rm
w
 hwFurti 
o
ema,g  ns
 d
y drought in V.  ubSny.g  sudciarcoburuluagtmah  tii nnin  b iVno.tf heurb nftyeig lr uedt ircsloeuo uliaalgn t(ahdF ti i ingin2
ru e u  bfr sai
igu
erVnoi
ff
nearg 
r
.tBf
e
t2 d
r
 he
innrui2 r
d
l r ai
e
n aeTft
gfilane i
n
gas
e 
slcn
t
rds
d
ubeoa
 s
tdi 
s
 il
r
incT
 
ces
o
l eaustoT a
u4l
if
  libay
l 
aoa)l
g tbl 
f
n.
h
tle (i
e
aeldFne
r
 et r4
,
i i 
 cat nig4
i
)srr
l
nc.
o
 u) e
eit
bef F.
ig
Ber a
yl
oTers
 a c
.et rte h
rco
ho i 2d
do
lte  
nn
eh
l
f a
ed
re iaisan
dsi
rsoctdm 
sitctieiS
 ola 
io
esiT
o.Vern
n f  a
nbas
 iie
,tbncg
 is,hcaa
.
 nl
 
 dt e
e
ib
nFan  
 rdosi 4ce
o 
fnuei)
r
 mif dnc.
 in
rBe 
tlotg T
h 
ri.cin
cV
 ulthn
e
ooeiti
.
le  
 nc Table 4. Compariso of effects of increasing drought in tweuo n
d
rt asealts
i
ocna 
tcwieitola a sa
n
fewr  e sb
,
air a
 
nitic
asin
n
 dl iicnas
d
t r
 
iyicfng eica
i
 dn
n
rSBost io
 
ni.efic
V.
 lldooe-ali n 
 
entirtuoeancnmest a s(ewcf eiarnbts i irlensu,ifm geLnr  ati ifinled-  
Table 4. Comparison ffuernergtsihule iyc suioellaidlt,a ,w  tihnhe ii lnteht etrhrebufieeyn l g ce
guo rsineocetuienll.na  Hlhtt
ea two
a ifiwnna
y s v eiVn s
e
.tie eug
grcrne,afi ttgin
ahlfiuet
beclli sc yaa
eoun s
siiltcn
 lwal.oc yHarr
e  bde
r
ionai
eewcs c sbeare
i
odec
gvati 
nedhisrn
i
  e
fi,c
Tsooafibel lf(efFe 4cigt. sCuorofemi n2p caarrneiasdso iTs
c
nTno
an
a agoibbl
t
fd l l(
l
eerF
y
 ffo 4i
 4ueg
in
.) cgCu.
c
t hsFr
r
o te
e
mo ir
a
f2np t
s iiaa
e
ntlwern
d
ci rsdos
 i
eoo 
n
aTsnTi
 
soal a
S
i oibn(bl
.
fLg 
 
l lf(
s
ee )F
c
 dff r4i4
atreg
b
.i)o lcCu.
riut t
u
sroyg e
m
mohc f2
 d
top  inaa
u
ndrn
r
c itirsd
in
wteoi aonT
g
of
  d
sn ae
toS chd
isosnbr 
an.bt e
n
isty leca
t
e a
lndsy bactr
 r dnoowurdu
emabc gs
r
ii nch d
es fti
aue gci
s
rrnni
e
tid n
d
iiVlfi g
 
ec.
bc o suad
ynonn
 rtdigte
r
llsuny
o
 iagt c
ud nwu
gedtla
hca,  rst
t
irnea
  es( aF gia
i
Bsgnae
g
.n rdd
-
infertile soil, S) on freshofg( l 
r
ifyee
o
l e dffi 
u
fre4ertl)
g
oridc.ltut 
he atn, dre vgitaarmdilnes cso notfe tnht e( msogi/l1 0c0oodi l fin gel ecdrFaasiWcstnie to)al neoyf  f, itd  nhVae e.ni cu ndrsnfeo egiainrulst ieiccVludoe.l n islg,i toLhyft a cinnodc ntrdweiaotsi oisnogsil  d(ffereorrtutiilgliethy, t L ci noa ntwdi oti osnosil  (ffeerrttiilliety,  Lc oandi  tait
d
oa
i
n,
t sB
io
 .( 
n
foel
,
re
 
tr
a
ia
n
lcee
d
, a
 
Le
i,n  aa
 
nn
V
dd
. 
  
infertile soil, S) on fresiS
uihn.
r  esB c1.a  obaFlrenurremdasc  heTia naye b iibelneylfd e 4d nfyeiretlidle asnodil,v Sit)a omni fnrriuT
)
sienct
r.onai
 o
sofl
 T
hib
B
egne
uh
lr u l t
.
yt(
gees i
e
iF
o
i 
h
lcnoe4
 
ilutli
tβge. d 
 r
sl( Ca
-
u(aom (
Fc
atiroF
caainlge
e
,m
gi r d/ i
agoS2
unpe 1)u
te
v 
  r 0aai
b
oirn0rte
ny 
nait
2s edg  mef2o
d  
r riu
aFT n
c
TrienfinaWns 
o
afoln hbeg
dnbuce)fr duol
  tlgTytoseenii 
e
io lcfff
hTn aet44ui
tb
eVlea.
t
 ld) 
 
snlc..b
l C.(ao  t
ew
t uH
F
alts io
 e(an
i
l 
4
m,m
aog g di
)
S4
sfwunu.gp  
 
))
 
vii 
rF
 /.a
s
cenioi1 
eniurotvTc
g 
n0ailtr
r2se0 ah
n
me
 
fo
 tt rrerga
aian,h
fi
iefi s,
n
n ts Fa
iiBo
chl hn
ad
Wces
af.em ogc
  nyos
Te n) oailod ff
itaetors
nlrier
b
leb
y
fcldao
e
n c.
lo 
i cV  u
,tetcH
i 
aers
n
 .g
 ta ( nb 
4h
umaeoh
c)
di,nc
efwrtc.g a i
 e
gv id
Fc
/nauen
ao
i1dct vic
s 0accit
nrree0udmwoe
 td
 r
t
lga n
e
ao,c
h 
i s
n
n tt o
ii
Faiesh
nat
 nWc,on
 
 e
m 
og
w
Btit
S lne) a. d
ia.
 nftwos
 eer
s
lfct
soer
e 
n a 
corVtw
iu,ts
ain ar .lg
t b(c aib
ch
umsteh
rsryieuantc g
e
ge s 
 
g 
mca,in
c
/ai uno
so
1agci
 
i 
e
0ncfini
it0ud
nwd-i
t 
 lfii
 
S. scabr m.  e  gaocti
n ostno w ctFaaW, nBtsitle) . l (
anfyofe
s
left erd
 
 r rVtw
itinaei.llc aic
c
ueters
ry,an e 
e
e Lsgac
a
,i u oasg
sae
iencnuddilfii 
  
  atictoaa,n nBst .l (yofle edrrtaeilcceer,a eeLa,  asaenndd   
S. scabrum. STc
fbeyrn tdtillre.a sbclaeby o
 
r4 
s
uiu
o
. ngimCc
lh
.o r
, 
metw aipnshae irVldei.s   oiuthSinibn 
eyg
.  S of
 
sBe u
c
c.fd r
o
 ia.set rcbioc
n
fforluale
tul
ueeb 
ea
mrcsrg
natoItuaht.sci
n
  l
 e t,iwfoa nSi
e
f en
r
 da )i n bs 
ti
uoVo cyn
lse
Tabl  4. Comparirs eod
 s
aSr
o
s.o
i
 isnu
l (
cgag
S
 bdh
)
rurt
 
r.tii hnugfrTini ngnefa esg i fdfiobBhrefltr  rc.yiet calio ffielu4uenl ee.lao  gt mdarcs
l
C(unathtoyF .saocgd it
 i nl edm,goh,i  a dinfretuSnpe e c)i rvaf nbgreoeiroec tya nirtaar2strwt  ehmod fisaalrno erilefdsn eoei ssonsds hru ocfobsgt   iogyTe iyl no ldffhiaefs etfdertb el oar drctnl(tunhoteFi tsa lg  deuii (4ntgoh m gy)sdiftu.nh o g  cirvFf itn/oeBlei1 oc  nti r0t.canrr2 dwt0eo mo  iti Vaalnogtheisin.  droii  Fsasuda noiWcocmgtn sioieTigl on) ladi(af sunfetoerb ee ioafre,icrnl  tnu,teVaui tilg t dl.nlii(4 aethunm dy,)tie tnf.a L  g ecgiFc   n/aoruBao1tn  in0ti.crV wld0du oet .ti el   o gthaein  troiFsatanoW, cm wsiBel ) a.i(af nfeoese lfre ire tin,trVin ial tl.iic ehtunery,e anef L ecgac, or usaoatienincldudetie l  taintoatn,  wsB .(a fosel  reitrnialceer, aeLea,  saaenndd   
iuSsnon.f iegslrcu t(aiFblceiurg usluaomtiral e,i  inS2n)   aiionnnnftd e efr ribSTsTentfioy.aisaf llhsibe beeldcr  l  layt(ersesibFio lo er4i4uiulig. ld)l smg. Cu.o  (HahF.iroF nlete,moi d rgSiw2ntp )uvi  a aleoirVertnvenai .s ed muf2or ibS T,ien nayl.tsgf  a  on hse( ubcdcLfre doi laytrce )enib aio luffT erts4ueula cda)snmcgb.to t ahl.rs i e(nl b tm,io  dniSi4fcgn ))v bi /a. noi1 VoctTcn0a.tiBr0 hdhmufre re ga nacief sn esogsFa hrsiunWct iogcyitcclne) oiead uentor e rl-baftodaon niVtwl utcaed .g ( narumai ahdsinct cg s igvbefid/iuei1angot ir0ace cntt0uhmwo i lfi gnaeoifn ctet  Fase rWc,ont noBiittln)l.  els Vftwyo elaf iernd agnrVttsiaen d.l (c aiumste riyain eguge gac,f /n uBeo1as-giir0en. cfi ut0uodi-i l gcae tuitir FoaslW,noca Besit)la.a s (eof   leafie rnrVta id.ilc une i,anf eLg, r uSBatioin.c lulodeal  aentrau,cm Bea.  seoc lieanrba icrneuafme,r  at inlde 
  Sicna.   nsBcta.l byor lβuienm-rcac.ac rereaoaets eebndyBe   idrBnairnr so aSfseus.i rsgcstiiacchlaae tob  s(rloFeuFirimlga, ruS ctd)eir luaeo nerB 2si  n rfoVarsagieionlsg s ids(dnhlLi a  r(cyT)oFaiaVuei bgloigdlguleh enar tre4an,a  )d 2ruc. e  evFnagaiogntaeBaurdr  mirdtS caThoilunaseillas baacimsnloct eunoai Vmn4tf eo i)etng.l,h e tnt er(ah mas eucog enciS/alo1go e0ncul 0otai ecgnun duFltimaW twit o)asaV noc sifa, g  iVabnn.nrc auudr nmeu gainSn usgo ieucVlduai. lc nuulmat asc abrumS o lanum sc 
Sso. silc a(bFriugmu.r e 2 and ST.a sbcleb r4u)m. . abrum  
Infertile soil (S) -   ata, B. oleraceae, and 
  
Fertile sobuTilyna (bg Ldule)ri o c4
Fu.ru lgCa
e
Fht
soahetm  ri
 
in
y
tnpi 
i
la i
e
eVnr
l
 i.t
d
ss
  Bras sica oleraceaeB rassicaV oiglenraa ucenageu iculataV igna unSgoulaicnuulmat asc abrumS o lanum scabrum  
 e
 
uoorSTnnilfil.eag   o(lrsbueLacfli ac)scebe o uffr4aiul.ela mc.Ct tHFa.so  e miornfwtp  ibilaeneorvc itsrseheooru ai,fn lset  gioh(rnuLfteg ii)e cl a eduffs rleacaocnotutarsdgb  ohiifntc  fianeccr itrtdweisla eocsa  oissbnoorgtiiule l dsmnf erator ntwuidlgait hsiynt  s c iinBog .nt dwoilfiieoticr osaanocnesitl a l(feyfe e irdrnttie ililicentry,f e eLacr osateinlde i  tions (fertile, L and  
Fresh yield  Fresh yield  i  fertilFer seoFsihl,  rSyt)ii leoelnB ds  rfo raiienls s fs(heLir cyt)ia ile lo dslo e 
IFainrnlea,f drSect )eriv ltaoiitnelB aes  mrfo rsaieols s is( hlcLi  o(cy)Sna iV)et  
 
eloidngl etn a r(anmad ucg evn/ai1gte0Bau 0m ir cagiun sFls aWcioctn)aV to eoifng lVetn  .r( auma nucggenS/ua1goie0ucl 0u ai lcgnau tuFalmaW, Bt )a.sV oc  ilfaeg rVbna.rc auue anmuegn,S  uago inuclud ailc nautualma, Bt a.s oc  laerbarcueame,S  ao nlda num sc abrum  
Table 4. CFoemrptialeri sonil  o(fL e)ff ects of increasing drought in two soil fertility co-n ditions (fertile, L and 
Fresh yield  s
ino iBl .( Foilgeruarcee a2e  abnyd d Traobulgeh 4t) .( Figure 2 aTnabdl T a4b. lCeo 4m).p Faroirs otnh ioafm effineec,t s t oef  cocnretaesnint gw darso iungchrte ains etw  o soil fertility co itions (fe rtile, L and 
bSy. s dcarbor
F
uu
rmegh.
s h yield 
Fresh yieldIFnefretrilteil eso Fsioel ri(tlLi l(e)S )sA oislcIF(noLefrr)ebtriiltcei l aesco siiindol fi l (S) Infertile soil (S)   
t in V. uS.g  (seuLcriat)cib lureul asmtoF a.i l e,i rnSt )iib lloeon  t
Bs hforri iaefnilless f (hresLtr iyit)cli ie ale la odsnol ae
 
 dinl
r, a diSnc )vef oeiatnraet m fi lrien ss hco oyinliseVt el-adin gn tan
 
  d(n
am di nug v /nBi1tg0.a u
 
0moi  lg
cein urFa lWccaoetn)aa etoe   fin nVt .i( unmnfgeg/ruS1t-io0i cl0ul
 
ea  l ga
n tFauW,m B).  soc
 
l fe
a rVba.c rueuanmeg, u ai 
 
Infertile soil (S) Infertile soil (S) ncudl ata, B. ol eraceae, and 
Fresh yield Fresh yield Fresh yield          
S. scabrum.I nfertile soil (S) 
Fertile soITsniolaf eib(lLr lt(e)iFl e4i
βg-.s Cu
c
oFiF
arole
r
em( 
o
rSr2tt
t
p)i i
e
aall
n
eern  
e
isds
  
oo nTiill a  o((bLfL le)e)
      
  ff 4e-) c.t Fs eorft ilneic lrseoil (L) - - -  - -   
FreIsnhf eyriteilled   so il (S) IFnefretritleil Bes orsaiols  i(lsL i(cS) a)  olIeFnrefarectrietlaeil Bes  o rs
aSaos
. is
ils ii
nc
(lsl 
ga
L i(cS
 bdru
)r) aV   
omu.g ht in two soil fe-r tility conditions (fertile, L and 
β-carotene β-carotene infertilβe -scoailr,o St)e onne  fresh yield a 
   
Fnedrt vilieta smoiinl  (cLo)n te-
oi glen raa ucenageu iculataV -i gna unS-go ul aicnuulmat asc abrumS -o  lanum sc abrum  
  -      -  
β-cIFF
anreef
o
rrett
trii
e
ltl
n
eeil  
eess 
 
o osiioll  i((lLL ()S)  )T
β -hciIIFanrfoetretnilee  soil (S) nt (mg/100 g FW) of V. unguiculata, B. oleraceae, and   
Faneemfrrettiriinltleiel   ess o osiioll   i((lLL ()S)  ) --  IFnefretrilteil Beso rsaiols  i(slL i(c)S a)  --o  leracea- eB rassicaV --oi leraceae Vigna unguiculata  Solanum sc abrum  
ST.a sbclaebr4u. mC.Io nfepratriile sno oilf  (eSff)e ctsIn offe rinlticl ree asisoli inlg ( Sd )r ou ght in tw o soil fe-r 
gna un-g uiculata S
  -o la num scabrum  
 tility cond itions (fertile, L an d  
Fresh yield Fresh yield  -         
β-carotene β-carotene infertilβeA -sscocFaiolre,or rSbtt)ieii llcone n ea s  c Infertile soil (S) - 
β-carotene Fertile soil (L) - -    
Fertile soil (L) Fertile sfoor
i
iie
dillls   
   
((hLL y))  i eld FFaneedrrtt iivllieet  assmooiilln  (( cLLo))n  te-n t (mg/1-0 0 g FW) of V . ungu--i  cu lata, B. oleraceae, a- nd     
Infertile soil (S) 
Ascorbic a cid AFβr-sec
I
csa
n
ohr
f
ro 
e
byt
r
iei
t
cen
i
 l
l
aed
e  c 
so il (S)F reIIFsn
n
hef
f
 re
e
ytr
r
iit
t
leei
i
ll
l
B de
e
s 
 
ro s
s
aio
o
ls i
il (S)
s(lL i(cS)a )  -
 
o leIF nreafrectreitlaeiilel es  o sTiolh ii(lelL   (aS)r V)r - iSd. scabrAumsc. orbic acid  oi gwn   sa s huonwgu t ir ceunldast oaf -
 
 i nt  eractSio- nl
 
  a (unpuwma srdc  as brluem a r 
   
-r 
 
o w : positi  ve, downwards red    arrow: neg-
AscInofrebritci laec Isindofi elr (tiSle)A ssocIIilnno(ffrSeeb)rrittciii lllaeec   ssidooii illl   ((SS))   - Infertile soil (S) -     
FFeerrtttiiilllee   ssooiiilll   (((LL)))   FFeerrttiillee  ssooiill  ((LL))  - IFnefretriiltleil  eso saiioltl  ii(vlL e()S) . ) H  - yp  hen s--i  gn
Infertile soil (S) Infertile soil (S)   indicate- s   no inte-- r a   ction.  -     -   
AFβr-seccsaohrro bytieicen laed c 
  
β-carotene  
 id Ascorbic acid  AThsciFaoemrrbtiiiinlclee a 
B
  sco
riadiil
s
l  
      
F  (
sLic) a oleF r
 earctielae es oil (L) V-i gn a ungu iculata -  S-o lanum sc abrum   
  -    
IInneffreetrirltteiil leseo  ssiool ii(llL  (()SS ))  FInefretrilteil eso siol i(lL ()S ) -  F
βA-sccIFaoreforrbttieiltcni l eas co Fiidel ri (tlLi l(e) )s oil I
F(
nLfertile soil (S) 
e)rtile soil (L) IFn
e
ef
r
re
t
tr
il
it
e
leiil
 l e
so
s o s
il (L) - - - - - 
Thiamine Thiamine Thiamine 4o il. ii(DllL  (
 
iS)s )c  -
 
-u s  sion   -        -  
 -- Ascorbic acid β-carotene   
  
ThiIFF
anee
mfrrett
irii
n
ltleei
el  
 esso osiioll  i((lLL ()S)  )
T hiIIanmfeirntieill e  soiill  (S)  I nfertile soil (S) -   
-   
Fresh yield      
til  il ( ) FFnIne
ef
fr
re
et
triirl
tl
te
eil
i 
 e
ls
s
eo
 os
 si
io
ol
l  ii(
(lL
lL
 (
 ()
S)
S 
 ) 
)--   
IFnefretrilteil eso sTiolh i(leL  (a)SO r)r -uo wr rse ssheoaw-r c thre dnedms oofn- i snttreartaecsti to-h na (tu gprweae--  rnd lse balfuye v aergroe wta:b ploess--  i trie vAscorbic acid  sep, odnowd ndwiffaredres nr--et        ldy a tror oswoi:l n feegr--
Thiamine ThiIanmfeirnteil e Isnofielr (tiSle) soil (S) Infertile soil (S)  -  
βA-sccororbteicn ea cid  -  - 
Infertile sTohiel  a(SrrT)o
h
 wiFas emsrhtioinillwee  
   
 stroeTiinlhl  d(eLs a )or  rf oinwtF se ersarhtcoitliweo n st ro(eTuainlhtp id(evwLs e a))or .r rfdH o-isnw y btpse l hrusaehecn ota iwsroring ot nrw (e uin:n ppddwosi sacoiartfdti evisnse  bt,ne  ldoruao eicwn tatinroe-r wrnoa wac( urt:id popswno r.sa eirdtdi v 
 
ase rb,r loduwoew : annr-er wogwa- r:d pso rse-id ti vaer,r odwow: nnewga- rds red arrow: neg-
AThsciIIFaonemrffrebtiriinlctteiie lla  esco  isdiol  ii(llL  ((S ))A  scI
I
on
n
rf
feebrrict
tii l
l
ae
e
c 
 
is
sTdo
oh i
ilel   ((aSSr))r - owI sn sfehrotwile t rsteToilnhiidlte ys (a S, or)drf rought stress, or its combination i-n  regard to the yie- ld and vitamin co-n centrations. 
ative). Hyphen sign aitnidveic)a. tHesy pn ho ein tseirganc atTiitnohidvneei. c )oa. btHe
 oinwt  se rsahcotiwon t r (eunpdws aorfd isn bt elruaec tairorno w (u: ppwosairtdiv se b, lduoew anrrwowar:d pso rseidti  vaer,r odwow: nnewga- rds red  -  - arrow: neg-
Fertile soil (L)   
β-carotene Infertiille  saotiiivll  e(S).) H  - yIpnhfenr tsiilgen s aiotniidvl ei(cS)a.) tH es
sye pnr vhosy pnhoe
 ei
 eid
n t
n  
se
tsi
i
en
rga
irgac
nc 
ncr
 t
 te
iino
iina
dn
ods
i
ne
.c 
i.c  
a
ain
te
t-e 
st sh
n 
 ne
o
o 
 
 δ
in13t
intC
er
er 
a
av
c  
ca
ti  
tl
o
iu
n
one
.
.s
 
 , i. e., less neg ative-  δ
13C values, in the three green 
Thiamine FFeerrttiillee  ssooTiilhl  (e(LL a))r  rowFs esrhtoilwe stroeTinhl de(Ls a )or rf o-inw tse rsahcotiwon t r(eTu4nh.p deDws  aiorsrrfdc o-iusnw  sbt se l ruisaohecn otai wrorn ot rw(eun: ppdwos saoirtfdi visne bt, e ldruaoecw tainrorwno wa (ur:d ppswo rsae-ird tdi vase rb,r loduwoew : annrerwogwa- r:d pso rseidti v aer,r odwow: nnewga- rds red  arrow: neg-
Thiamine Infertile soil (S) - -   - 
Thiamine  
Ascorbic acid 4at.i Dvei)s. cHuyspFsheioertnni l sei gsno 4aTiitln.hi (dDveLei cia))sa. r ctrHeousyws pnF sshoei so erihtnnio tl sweeir g satnocr 4aetiiitln.oi (dDvnLeis.ci ))soa.  ctfHe- ui syns pntsehoiro eainnc t sieoirgnan c( tuiinopdnwi.c aartde- s bnlou ien aterraocwti:o pno. siti 
Infertile soil (S) O r research  demonstrates that green  vleea, fdyo wvengweatardbsl ers-e  dre asrproownd: n degiff-Infertile Isnofeilr t(iSle) soil (S) eren-t ly to soil fer-
ThiIFanemfretirinlteeil  eso siol i(lL ()S )T hiamine 4at.i Dvei)s. cHuysps
- 
 hioenn  sign 4in. dDicisacteuss ns
- - 
 oio innt erac tion.    
The aOrruorw Irsne sfseheroatwrilce ht rs edoneidlm s( SOoonusrt raetseesa trhchat d germeeOonnu lsert arafeytse evsae trghcehatt ad gberlmeeso nrne lssetparaofytne dvse tdghieaffttae gbrerlenest nlrye l steopa ofsyon idvl e fdgeireff-taebrelenst lrye stop osonidl  fdeirff-erently to soil fer-
4. Discussion 4. DisO)cf  uinrsI
 - 
Ascorbic acid  sniofenr tile st4o
il
. i
i
Dl
t y(iS
, 
s)dc 
rought str ess, or its c mbin tion i  r  gard to the yie- ld and vitamin co-n centrations. 
The arrows show trends of interaction (upwardsTbhleu eaarrrroow
FInefretrilteil eso siol 
 trse:e rpsashoecsotaiitworivcn eth r,(e dudnopewdwmsn awoOorfand urissndrs tsb tsrelraierueotasdeenec sataa ir rtorrrhocnowha w(t :ud :ng peperwgmoeasaetoirintvndi evlss)ee .tba,rH lafduyytoepe wv hsaee nrtngrhwoeawattar :dgb psrlo ersesei ndtrie  vlaseerpa,r oofdywno wdv: ne ndgewgieffa-taredbresl enrset ldrye a stropr ooswonid:l n  fdeegirff-- erently to soil fer-
sign indicates o in eracttaiitlnii(vlt.L ye()S),  .d)  H ryopuhgehnt  ssitgrnet sisli,t oyr,  dit-rs o cuogmhbt isntraettTsiioslhi,nt eoy  iro,n  dbi rtsrseeo gcr
 
uaovgrmedhbt  t iisont rtcahertsieosa y,ns oie eir nli dni rt  seat h
 
gncaoed rm δdv1b i3tCioan  mtav
 
htaiienlou  ynceio sei-n,l  dc ir.e ean.gn,t adlrera dsvtsi io toane mstg
 
h. iaent  yicvioenl dδc1e 3anCnt drva avtliiuotanemss,.  iin  ctohne ctehnrterea tgiroenesn.  
Thiamine Tt4
ain
ih
t.il 
d
ieD
v eiactyi
)
,rs
a. 
 rdc
tHoeuwsy  ns oros
ph
uisgo
 ehihn
no t
t w
seirg tanrceT tinihnodedns i.a c ates no interaction. 
 stretsisli,t oyor,r  rfdi otirnswo tcseuo rsgamhhcotbtiw oisnnt tr r  e(teusinopsd,nw so  aiorr fdi  rtisns  bgtcelruramedc tab itroiornno t wh(tuie:o p pynwoi saiirltdd irv s ae bgn, ladduroe dw a itnroarwo mtwahire:nd  p syco iroseenildtdci vae aernn,r toddrwao vtw:i inotnaenwgmsa-. irnd sc roendc aernrtorwat:i noengs-. 
IFnefretrilteil e
The oObuser rrveesdea irncchr Tedaheseme o Ooibnnus sterht rrevae etsδede1s3a C itrnhc cvharat Ted lgauhersemee seo ,Ooi nbnin.u s elsteer.ht, rar evlafee yetsδsed e1vss3a eC intrnghce cvehagrtat aead lgtaubeirslvemeesees ,o i  nδnrin.e 1 els3tseC.htp,ar e laofve ytnδase 1dvlss3u eC ntdeghe siveaffg,t atiaae lngtubri erlvteenhseeste,   nlδ riyt.e 1ehl 3steC.rop,ae   lofvseyona s gidvlslur  e nefdegeesirenffg,-t  iaaentbri elvtenheste  lδ ryte1h 3stCrope  ovseona gidllur  efdeeesirnff,-  ienr etnhtel yth troe seo gilr efeern- 
so sti
o
ill 
i
i(
l
tL
 (
y)S, 
) a
 drought stretT
t
sislh
ivee )i,t oyro,O
. 
  db
H
it-usrs 
yeor
p
 c rurov
hegme
esnhde
 
bta 
s
 iisr
ig
ntcrc
n
aher
 a
tt Tsie
idtnioslah
i
ie
dv
,nst em
ei
oye  
c)
iro 
a.
,no i
 
 dbn
tHe
i rtsr 
sy
sete
 
o hgt
pn
cruaoev
hoag rme
 etδidhe
n1bs
 
t 3
t st C 
eiisot
ir
nh
g
t  
a
rtcav
nacherta
 ttisie 
ilnog
o
sau
dn
 y,nrs e
i
oie
.
 s
c 
eier n,
a
li  dn
t
i i
e
rt.   sl
s
eate .
 hngnc,a aoedl
ofe ry
 
m δ
i
dsv 
n1vsb i3
t teC
e
inoang
re  
a
mtaveg
c
hta
t
ia
i
ienl
o
otub  yi
n
nclveie
.
o s
 
eis
-
n,l 
 
  -  dδrc ir.1e e3asnC.gnp,t a dlrovera nadsvtdlsi iuo t oadnee mssitffg,h.  iiaentr  yi ecvtionhentel ldδ cyt1e h 3atnCronte drvseao a vtgiliilurot efaneemssrn,.-  i in  ctohne ctehnrterea tgiroenesn.  
Thiamine 4. Discussion 4. Discussion 4. Discussion  
TThhee  aorbroswersv sehdo win ctrreTetniahldisetsey  o o,i bnfd s irtneohtreuevr geaδdhc1t3t iCi osn ntcvr re(aTeuslauhpss,we eo sao ,rir bn idi.st estse. h b,rc evlloue emδsed1s a3b Cinrinrne ocvagwrataeil:taou pisnveoese si , nii δnti i.1rv e3teeC.h,g,  e ladve roδasdw1ls3u  Ctnneowe s vtg,ah aiarlendtu i syvte hirseeee,  ldδ idt.1 eha 3aC.rr,nre  olvdewa s gvls: uri ntneeaeesgmng,-Infertile soil (S) -   ianti  vtchoee nδ ct1he3Cnret vrea gtliuroeenessn, . i n the three green 
Our research daetimveo)O.n Hsutyrp arhteessne atshrigcanht 4Tidgn. herdDeemi ciesoaOoncbtneuslsseer tn sra rvoaifeoye tsiendnevsat   eitrnrhgcachaec4r ted ia.go Daebnrsmlee.ei escussion 
 oinnnr  lsetehtsarpeaf ytδe 1vs3deC tgh dvea itatfa lfguberleesesn,  nrit.le elyse.p,a tlofeyns sdvso e nidgleieffgtaaetbrielvenest  lδrye1 3stCop  ovsonaidllu  fdeesirff,- ienr etnhtel yth troe seo gilr efeern- 
fertility, drought streTtsihslie,t oyar,r r diotrswocsuo sgmhhobtw isnt tarretetisnoisldni,t soyi noOr,  fdir utiernsrgo  tcreauoerrgasmdhectbatio orisncntrhha e(t eudsiopyse,nwim eo ailOrondr ndi urtasssern t b gcrdlaoeutrvsmeedei staba a trtriomrhnco htaiwhntt d ie:go ce prynomoein seeiocilntden i rvnl seeaettgan,rr aafddyttro ied owvs ine tntoagshw. metaahttair endgb  srylc eiroeese lndrdce  lae searnpanrtoofdrywna  tdv:i ineo tdagengimesff-t. aienbr elcenostn lrycee stnopt osronatidli o fdenirsff-. erently to soil fer-
 The obse 4at.i rved increaTseh Dveien i)os. tbc H huse
yesprδsvhi1oe3eCnnd  sivingacnlru tTeiienlahisdste,yie cio ,.a iedbnt.e,sr steol henruesvogs e δihdnn1t3te  Ceisgnrt aarcvectratitseivilsloauie,nst eoyeδ.s  1r,, i  3dniiCt.r esto .hvc,u oealge mlδush1sbte3  Csinsn,te ravigentaasilotstuhi,nv eo seirnt,   hδi irt.r1ese3eC .gec, ao lgvermradselsb uet inoene stag,ht iaienot yi nvti heeinel dδ  rt1 he3aCgrnea dver a dvgl iurteoaee mstn,h i ien  y ctioheneld cte hanrntedrea  vtgiiroteanemsn. i n concentrations. 
leafy vegetables with a de
  Ocr
 u
era sriensgeairrrcihg Tadhteeemd oowbnassetterrvaaetedms  oitnhucanrtTte gathyrsepe eo iicbna s lltelhyraevfi yneδd d1v3 ieCicnga cvetertaeatlaubhsleeeses ,ix nrip.e etes.hp,r ieloee nnδs1dcs3 eC ndde ivffgaaelturievenset,  lδiy.1e 3tC.o,  lvseoasilslu nfeeesrg,- ianti vthee δ t1h3Cre vea glureeesn,  in the three green 
water stress for C3 p4. Discussion 
 tlialintyts, d[1r7o,u3g0,h3t1 s].tress, or its combination in regard to the yield and vitamin concentrations. 
The yields of tThheet hoOrbeuseer rrgveresedeea nirnclchera edfayesmev oienng sethtraeab tδlee1s3sC thm vaoat lsgutreesste,r noi. nele.g,a llfyeys dvs engceregetaatsbielvedes  iδrne13sCtph ovenaldlou wdesiff, ienr etnhtel yth troe seo gilr efeern- 
 fertility  soil (endosttailgitnyi,c darloisuogl)hct osmtrepsasr, eodr ittos tchoemfberintialetiosoni lin(e rnedgaorledp ttoi cthcea myibeilsdo al)nudn vditearmin concentrations. 
all wate The ob served increase in the δ13C values, i.e., less negative δ13
 ring regimes due to the lowe total soil fertility in the low fertility soil. B. oCle vracleuaees, in the three green 
had the highest fresh biomass yield among all the three green leafy vegetables in both soil
treatments under control and mild drought, therefore indicating its lower sensitivity to
 
soil fertility compared to the other two vegetables. However, the decreasing yield rate by
 drought was higher in B. oleraceae than V. unguiculata and S. scabrum, confirming that B.
oleraceae had the highest susceptibility to water stress among the three vegetables measured.
Likewise, Brassica spp., such as kale (B. oleracea) [33] and Chinese cabbage (B. rapa) [34], are
sensitive to drought stress.
Among the three green leafy vegetables, S. scabrum was the most vulnerable to low
soil fertility regarding the fresh biomass yield. However, in the fertile soil, the S. scabrum
yield was higher than V. unguiculata under mild drought and in the control. Although
the fresh yield of V. unguiculata was lower than that of B. oleraceae and S. scabrum under
the control (75% PC), the decreasing yield rate by drought was lower than the others.
Therefore, V. unguiculata was the most drought-tolerant vegetable among the three green
leafy vegetables. High drought tolerance under the severe drought of V. unguiculata was
also identified in a comparison with two other green leafy vegetables: Amaranthus spp. and
Corchorus olitorius [35].
The thiamine concentration was significantly increased by the combination of severe
drought and low soil fertility in the leaves of B. oleraceae and V. unguiculata, whereas in
S. scabrum, the thiamine concentration was only increased in low soil fertility, but not by
drought. The increased thiamine concentrations were possibly due to the effect of induced
oxidative stress through severe drought stress [36] and/or proton (H+) rhizotoxicity (lower
Agriculture 2023, 13, 984 12 of 15
pH in the low fertility soil) [37]. Oxidative stress induces the precursors of thiamine; hence,
thiamine is upregulated [12,36,38].
The authors of [14] observed that β-carotene concentrations of kale responded posi-
tively to increasing soil N content, which was also observed in this trial (33% higher mineral
N level in the fertile soil than in the low fertility soil). However, there were no significant
β-carotene concentration changes in the leaves of the investigated green leafy vegetables
by soil fertility under well-watered conditions in our trial. The different results compared
to the literature might be explained by the N-fertilizer dose in the experiment by [14] being
217% higher between treatments, therefore much larger than the 33% difference in the
present trial. In addition, as the soil materials of this study were under acidic conditions, the
availability of soil nitrogen (N) might also be restricted by soil acidity, the form of nitrogen
(NH4 vs. NO3) thereby not allowing for the full uptake of N present in the soil [39].
In contrast to thiamine, β-carotene showed a different reaction to the drought treat-
ments between the fertile and interfile soils. The β-carotene concentrations were signif-
icantly decreased under the combination of drought and low soil fertility treatments in
the leaves of V. unguiculata and S. scabrum. In the fertile soil, the β-carotene concentration
was increased significantly in S. scabrum under severe drought. The latter result is consis-
tent with the effect of severe drought (30% field capacity) on β-carotene concentrations in
the leaves of amaranth, where the total antioxidant capacity was increased with induced
drought stress [40]. The opposite effect that was observed in S. scabrum in low soil fertility
can be attributed to the fact that S. scabrum is most affected by lower soil fertility, implying
that it may be less susceptible to drought than to nutrient stress.
The ascorbic acid concentration increased with more intensive drought conditions in
S. scabrum, regardless of the soil fertility, and in V. unguiculata in low fertility soil. A higher
concentration of ascorbic acid during drought was also found in amaranth leaves, with an
elevation of 163% during a severe drought treatment [40].
The ascorbic acid concentration was significantly reduced in the leaves of B. oleraceae
by increasing drought intensity in both soil types. Similar results of lower ascorbic acid
concentrations by drought were identified in rosemary (Rosmarinus officinalis L.), sage
(Salvia officinalis L.), lemon balm (Melissa officinalis L.) [41], and soybean (Glycine max L.
Merr) [42]. Our observed highly variable species response of ascorbic acid content to
drought stress confirms results by [42]; however, this does not allow us to make general
recommendations.
Regardless of the soil fertility, the absolute amounts of vitamins decreased with lower
yields, although the concentrations of the analysed vitamins were mostly higher. The reason
for this was the loss of total plant biomass as a result of drought severity. A similar drought
reaction was observed regarding the mineral nutrient concentrations in maize (Zea mays L.)
grains and cassava (Manihot esculenta Crantz) tubers during a mild drought in Kenya [17],
i.e., while the nutrient concentrations of minerals increased as a result of mild drought,
only the total mineral amount (yield x concentration) of calcium was significantly higher
compared to a normal season. Therefore, higher vitamin concentrations under drought
stress, observed particularly for the thiamine and ascorbic acid levels of V. unguiculata and
S. scabrum, could not compensate for the loss of the total biomass.
Droughts are known to affect human health, particularly through the lower production
of foods [17,43]. Droughts, often caused by El Niño–southern oscillation (ENSO) events,
occur with increasing frequency in the southern hemisphere [43], which unfortunately also
coincides with areas with high nutrient deficiencies [44]. The results of this study show that
drought would also affect the total production of the vitamins A, B1, and C in both areas
of high and low soil fertility, thereby reducing vitamin levels in many already nutritional
deficient geographic areas. In areas with lower soil fertility, the negative impact on diets
worsens as they show both lower mineral nutrient concentrations [13] and predominantly
(vegetable-dependent) significantly lower vitamin concentrations and yields.
Increasing agrobiodiversity by including different species, even of the same food group
(in this case, green leafy vegetables), can, however, increase food and nutrition security. This
Agriculture 2023, 13, 984 13 of 15
study shows that green leafy vegetables are differently adapted to stress, while producing
one or two vitamins in a higher concentration than the others. B. oleraceae, for example, is
less susceptible to low fertility soils; however, it is more susceptible to drought. Therefore, to
optimally cover all nutrient needs, the focus must be placed on rehabilitation of soil fertility
linked with intelligent agrobiodiversity and dietary diversity to enhance the probability of
adequate nutrient uptake and to minimize the risk for malnutrition.
5. Conclusions
The research conducted in this study covers a new area of research, in that it not only
studies the effects of the combination of drought and soil fertility on the quantity of plant
production, but also observes the resulting vitamin production.
The results of the trial show that both drought and varying soil fertility can strongly
affect vitamin concentrations and final amounts in plants. The varying results observed
during the trials show the importance of consuming a variety of foods, particularly when
consuming foods from regions with environmental stressors, to fulfill nutritional needs.
The co-existence of increasing drought events with increased soil degradation in areas
with high levels of malnutrition makes it vital to include research on food quality into
agricultural trials. The results of such an inclusion could be used to form recommendations
for the plants that are best to cultivate in different geographic regions, and could allow
particularly rural areas to fulfill their nutritional needs.
The results of this study can be used to derive recommendations as to which green
leafy vegetables can be used under which conditions to maximize vitamin production.
Supplementary Materials: The following supporting information can be downloaded at: https://
www.mdpi.com/article/10.3390/agriculture13050984/s1, Table S1: Mean temperature and humidity
of the greenhouse and the first growing season (the data recorded from 21 April to 2 August in 2019)
of the project areas in Uganda and Kenya.; Table S2: The gravimetric amount of 100% pot capacity
(PC), 75% PC, 50% PC, 25% PC, and a single pot with two soil types (fertile soil; cambisol and infertile
soil; alisol).; Table S3: Summary of chemical properties of collected soil samples in Tauchenweiler
and Höwenegg, Germany (Stahr & Böcker, 2014).; Figure S1: A sample layout of a 4 * 6 factorial
experiment involving three species (SW: B. oleracea, CP: V. unguiculata, and BN: S. scabrum), two soil
fertility (L: fertile soil and S: unfertile soil), and two drought treatments with a double number of the
control (DC: drought control, DM: drought mild, and DS: drought severe) in a randomized complete
block design with six replications. The layout was designed using the SAS program.; Figure S2:
δ13C measurements of samples of B. oleracea (SW, •), V. unguiculata (CP, +), and S. scabrum (BN,4)
according to the mean of irrigated water amount for each treatment in the greenhouse trial (n = 4 per
pot capacity of species). Regression respective formula and R2 are given. The triple asterisk indicates
significance at p < 0.001.
Author Contributions: Conceptualization, S.F.; Data curation, T.P.; Formal analysis, T.P., S.F., C.L.,
T.H. and G.C.; Funding acquisition, S.F., T.H., I.J. and G.C.; Investigation, S.F., C.L., I.J. and G.C.;
Methodology, T.P., S.F. and C.L.; Project administration, S.F., T.H., I.J. and G.C.; Resources, S.F.;
Supervision, S.F., C.L., T.H., I.J. and G.C.; Validation, T.P., C.L. and T.H.; Visualization, T.P.; Writing—
original draft, T.P. and S.F.; Writing—review & editing, S.F., C.L., T.H., I.J. and G.C. All authors have
read and agreed to the published version of the manuscript.
Funding: The study was conducted in the project “Education and Training for Sustainable Agriculture
and Nutrition in East Africa (EaTSANE)”. The project is part of the LEAP Agri program, a joint
Europe Africa Research and Innovation (R&I) initiative related to Food and Nutrition Security and
Sustainable Agriculture (FNSSA). This study was financially supported by the German Federal
Ministry of Food and Agriculture (BMEL) based on the decision of the Parliament of the Federal
Republic of Germany through the Federal Office of Agriculture and Food (BLE) (2817LEAP03).
Institutional Review Board Statement: Not applicable.
Data Availability Statement: On request, data can be made available.
Agriculture 2023, 13, 984 14 of 15
Acknowledgments: The authors gratefully acknowledge the assistance of Alexander Koza for facili-
tating the work with the HPLC in the midst of the pandemic. We would also like to acknowledge
and thank Sang-eun Bae for her help in the greenhouse.
Conflicts of Interest: The authors declare no conflict of interest. The funders had no role in the design
of the study, the collection, analysis or interpretation of the data; in the writing of the manuscript or
in the decision to publish the results.
References
1. Ugandan Bureau of Statistics (UBOS); ICF. Ugandan Demographic and Health Survey 2016; UBOS: Kampala, Uganda; ICF: Rockville,
MD, USA, 2018.
2. Yang, R.Y.; Fischer, S.; Hanson, P.M.; Keatinge, J.D.H. Increasing micronutrient availability from food in Sub-saharan Africa with
indigenous vegetables. ACS Symp. Ser. 2013, 1127, 231–254. [CrossRef]
3. Whitfield, K.C.; Bourassa, M.W.; Adamolekun, B.; Bergeron, G.; Bettendorff, L.; Brown, K.H.; Cox, L.; Fattal-Valevski, A.; Fischer,
P.R.; Frank, E.L.; et al. Thiamine deficiency disorders: Diagnosis, prevalence, and a roadmap for global control programs. Ann. N.
Y. Acad. Sci. 2018, 1430, 3–43. [CrossRef] [PubMed]
4. Rowe, S.; Carr, A.C. Global vitamin c status and prevalence of deficiency: A cause for concern? Nutrients 2020, 12, 2008. [CrossRef]
[PubMed]
5. Lane, D.J.R.; Richardson, D.R. The active role of vitamin C in mammalian iron metabolism: Much more than just enhanced iron
absorption! Free Radic. Biol. Med. 2014, 75, 69–83. [CrossRef]
6. Ojagbemi, A.; Okekunle, A.; Olowoyo, P.; Akpa, O.; Akinyemi, R.; Ovbiagele, B.; Owolabi, M. Dietary intakes of green leafy
vegetables and incidence of cardiovascular diseases. Cardiovasc. J. Afr. 2021, 32, 4. [CrossRef]
7. Stuetz, W.; Gowele, V.; Kinabo, J.; Bundala, N.; Mbwana, H.; Rybak, C.; Eleraky, L.; Lambert, C.; Biesalski, K. Consumption of
Dark Green Leafy Vegetables Predicts Vitamin A and Iron Intake and Status among Female Small-Scale Farmers in Tanzania.
Nutrients 2019, 11, 1025. [CrossRef]
8. Yang, R.Y.; Keding, G.B. Nutritional contributions of important African indigenous vegetables. In African Indigenous Vegetables in
Urban Agriculture, 1st ed.; Shackleton, C.M., Pasquini, M.W., Drescher, A.W., Eds.; Earthscan: London, UK, 2009; pp. 105–143.
9. Moyo, S.M.; Serem, J.C.; Bester, M.J.; Mavumengwana, V.; Kayitesi, E. (2020) African green leafy vegetables health benefits beyond
nutrition. Food Rev. Int. 2020, 37, 601–618. [CrossRef]
10. Asensi-Fabado, M.A.; Munné-Bosch, S. Vitamins in plants: Occurrence, biosynthesis and antioxidant function. Trends Plant Sci.
2010, 15, 582–592. [CrossRef]
11. Mattos, L.M.; Moretti, C.L. Oxidative Stress in Plants Under Drought Conditions and the Role of Different Enzymes. Enzym. Eng.
2016, 5, 136. [CrossRef]
12. Fitzpatrick, T.B.; Chapman, L.M. The importance of thiamine (vitamin B1) in plant health: From crop yield to biofortification. J.
Biol. Chem. 2020, 295, 12002–12013. [CrossRef]
13. Fischer, S.; Hilger, T.; Piepho, H.-P.; Jordan, I.; Karungi, J.; Towett, E.; Shepherd, K.; Cadisch, G. Soil and farm management effects
on yields and nutrient concentrations of food crops in East Africa. Sci. Total Environ. 2020, 716, 137078. [CrossRef]
14. Kopsell, D.A.; Kopsell, D.E.; Curran-Celentano, J. Carotenoid pigments in kale are influenced by nitrogen concentration and form.
J. Sci Food. Agric. 2007, 87, 900–907. [CrossRef]
15. Onyango, C.M.; Harbinson, J.; Imungi, J.K.; Van Kooten, O. Influence of maturity at harvest, N fertiliser and postharvest storage
on dry matter, ascorbic acid and ß-carotene contents of vegetable amaranth (Amaranthus hypochondriacus). Int. J. Postharvest.
Technol. Innov. 2011, 2, 180–196. [CrossRef]
16. Cai, W.; Borlace, S.; Lengaigne, M.; van Rensch, P.; Collins, M.; Vecchi, G.; Timmermann, A.; Santoso, A.; McPhaden, M.J.; Wu, L.;
et al. Increasing frequency of extreme El Niño events due to greenhouse warming. Nat. Clim. Change 2014, 4, 111–116. [CrossRef]
17. Fischer, S.; Hilger, T.; Piepho, H.-P.; Jordan, I.; Cadisch, G. Do we need more drought for better nutrition? The effect of precipitation
on nutrient concentration in East African food crops. Sci. Total Environ. 2019, 658, 405–415. [CrossRef]
18. Soares, J.C.; Santos, C.S.; Carvalho, S.M.P.; Pintado, M.M.; Vasconcelos, M.W. Preserving the nutritional quality of crop plants
under a changing climate: Importance and strategies. Plant Soil 2019, 443, 1–26. [CrossRef]
19. D’Oria, A.; Courbet, G.; Billiot, B.; Jing, L.; Pluchon, S.; Arkoun, M.; Maillard, A.; Roux, C.P.; Trouverie, J.; Etienne, P.; et al.
Drought specifically downregulates mineral nutrition: Plant ionomic content and associated gene expression. Plant Direct 2022, 6,
e402. [CrossRef]
20. Borrelli, P.; Robinson, D.A.; Panagos, P.; Lugato, E.; Yang, J.E.; Alewell, C.; Wuepper, D.; Montanarella, L.; Ballabio, C. Land
use and climate change impacts on global soil erosion by water (2015–2070). Proc. Natl. Acad. Sci. USA 2020, 117, 21994–22001.
[CrossRef]
21. Fischer, S.; Hilger, T.; Piepho, H.-P.; Jordan, I.; Cadisch, G. Missing association between nutrient concentrations in leaves and
edible parts of food crops—A neglected food security issue. J. Food Chem. 2021, 345, 128723. [CrossRef]
22. Turner, N.C. Imposing and maintaining soil water deficits in drought studies in pots. Plant Soil 2019, 439, 45–55. [CrossRef]
23. Pérez-Llorca, M.; Fenollosa, E.; Salguero-Gómez, R.; Munné-Bosch, S. What is the minimal optimal sample size for plant
ecophysiological studies? Plant Physiol. 2018, 178, 953–955. [CrossRef] [PubMed]
Agriculture 2023, 13, 984 15 of 15
24. Bramley, H.; Turner, N.C.; Siddique, K.H.M. Water use efficiency. In Genomics and Breeding for Climate-Resilient Crops, 1st ed.; Kole,
C., Ed.; Springer: Berlin/Heidelberg, Germany, 2013; Volume 2, pp. 225–268. [CrossRef]
25. Akhtar, S.S.; Amby, D.B.; Hegelund, J.N.; Fimognari, L.; Großkinsky, D.K.; Westergaard, J.C.; Müller, R.; Moelbak, L.; Liu, F.;
Roitsch, T. Bacillus licheniformis FMCH001 Increases Water Use Efficiency via Growth Stimulation in Both Normal and Drought
Conditions. Front. Plant Sci. 2020, 11, 297. [CrossRef] [PubMed]
26. BSI Standards: 2014: BS EN 14122:2014; Foodstuffs—Determination of Vitamin B1 by High Performance Liquid Chromatography.
BSI: London, UK, 2014.
27. Wald, J.P.; Nohr, D.; Biesalski, H.K. Rapid and easy carotenoid quantification in Ghanaian starchy staples using RP-HPLC-PDA. J.
Food Comp. Anal. 2018, 67, 119–127. [CrossRef]
28. World Health Organization; Food and Agricultural Organization of the United Nations. Vitamin and Mineral Requirements in
Human Nutrition, 2nd ed.; World Health Organization: Geeneve, Switzerlnd, 2004; 341p.
29. Hill-Mündel, K.; Schlegl, J.; Biesalski, H.K.; Ehnert, S.; Schröter, S.; Bahrs, C.; Nohr, D.; Nüssler, A.K.; Ihle, C. Preoperative
Ascorbic Acid Levels in Proximal Femur Fracture Patients Have No Postoperative Clinical Impact, While Ascorbic Acid Levels
upon Discharge Have a Major Effect on Postoperative Outcome. J. Clin. Med. 2019, 9, 66. [CrossRef]
30. Clay, D.E.; Engel, R.E.; Long, D.S.; Liu, Z. Nitrogen and water stress interact to influence carbon-13 discrimination in wheat. Soil
Sci. Soc. Am. J. 2001, 65, 1823–1828. [CrossRef]
31. Schmitter, P.; Dercon, G.; Hilger, T.; Hertel, M.; Treffner, J.; Lam, N.; Duc Vien, T.; Cadisch, G. Linking spatio-temporal variation of
crop response with sediment deposition along paddy rice terraces. Agric. Ecosyst. Environ. 2011, 140, 34–45. [CrossRef]
32. Hanson, P.; Yang, R.Y.; Chang, L.C.; Ledesma, L.; Ledesma, D. Carotenoids, ascorbic acid, minerals, and total glucosinolates in
choysum (Brassica rapa cvg. parachinensis) and kailaan (B. oleraceae Alboglabra group) as affected by variety and wet and dry
season production. J. Food Compos. Anal. 2011, 24, 950–962. [CrossRef]
33. Pathirana, I.; Thavarajah, P.; Siva, N.; Wickramasingh, A.N.K.; Smith, P.; Thavarajah, D. Moisture deficit effects on kale (Brassica
oleracea L. var. acephala) biomass, mineral, and low molecular weight carbohydrate concentrations. Sci. Hortic. 2017, 226, 216–222.
[CrossRef]
34. van Averbeke, W.; Netshithuthuni, C. Effect of irrigation scheduling on leaf yield of non-heading chinese cabbage (Brassica rapa L.
subsp. chinensis). South Afr. J. Plant Soil 2010, 27, 322–327. [CrossRef]
35. Maseko, I.; Ncube, B.; Tesfay, S.; Fessehazion, M.; Modi, A.T.; Mabhaudhi, T. Productivity of selected african leafy vegetables
under varying water regimes. Agronomy 2020, 10, 916. [CrossRef]
36. Rapala-Kozik, M.; Kowalska, E.; Ostrowska, K. Modulation of thiamine metabolism in Zea mays seedlings under conditions of
abiotic stress. J. Exp. Bot. 2008, 59, 4133–4143. [CrossRef]
37. Borhannuddin Bhuyan MH, M.; Hasanuzzaman, M.; Nahar, K.; Mahmud, J.A.; Parvin, K.; Bhuiyan, T.F.; Fujita, M. Plants behavior
under soil acidity stress: Insight into morphophysiological, biochemical, and molecular responses. In Plant Abiotic Stress Tolerance:
Agronomic, Molecular and Biotechnological Approaches; Hasanuzzaman, M., Hakeem, K.R., Nahar, K., Alharby, H.F., Eds.; Springer
Nature: Basel, Switzerland, 2019; pp. 35–82.
38. Hanson, A.D.; Beaudoin, G.A.; McCarty, D.R.; Gregory, J.F. Does abiotic stress cause functional B vitamin deficiency in plants?
Plant Physiol. 2016, 172, 2082–2097. [CrossRef]
39. Latifah, O.; Ahmed, O.H.; Majid, N.M.A. Soil pH buffering capacity and nitrogen availability following compost application in a
tropical acid soil. Compost. Sci. Util. 2018, 26, 1–15. [CrossRef]
40. Sarker, U.; Oba, S. Drought stress enhances nutritional and bioactive compounds, phenolic acids and antioxidant capacity of
Amaranthus leafy vegetable. BMC Plant Biol. 2018, 18, 258. [CrossRef]
41. Munné-Bosch, S.; Alegre, L. Drought-induced changes in the redox state of α-tocopherol, ascorbate, and the diterpene carnosic
acid in chloroplasts of Labiatae species differing in carnosic acid contents. Plant Physiol. 2003, 131, 1816–1825. [CrossRef]
42. Seminario, A.; Song, L.; Zulet, A.; Nguyen, H.T.; González, E.M.; Larrainzar, E. Drought stress causes a reduction in the
biosynthesis of ascorbic acid in soybean plants. Front Plant Sci. 2017, 8, 1042. [CrossRef]
43. Masih, I.; Maskey, S.; Mussá, F.E.F.; Trambauer, P. A review of droughts on the African continent: A geospatial and long-term
perspective. Hydrol. Earth Syst. Sci. 2014, 18, 3635–3649. [CrossRef]
44. von Grebmer, K.; Bernstein, J.; Wiemers, M.; Schiffer, T.; Hanano, A.; Towey, O.; Chéilleachair, R.N.; Foley, C.; Gitter, S.;
Ekstrom, K.; et al. Global Hunger Index, 16th ed.; Welthungerhilfe: Bonn, Germany, 2021; 60p. Available online: https://www.
globalhungerindex.org/ (accessed on 3 August 2022).
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual
author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to
people or property resulting from any ideas, methods, instructions or products referred to in the content.