Agro-anatomic and genetic analyses of kenaf (Hibiscus cannabinus L.) and its crude oil sorption capacity

Oil spillage is a significant environmental threat in Nigeria. Although synthetic sorbents are used in cleaning oil spill, they have negative impacts on the environment. Kenaf sorbent is a cheap and effective natural sorbent that can be used as an alternative. Nonetheless, the genetic diversity among kenaf accessions grown in Nigeria is very high, making it difficult to identify accessions with high sorption capacity. Hence, it is crucial to evaluate morphological variabilities and Quantitative Traits Loci (QTLs) among kenaf accessions in selecting genotypes with good Sorption Capacity (SC). Therefore, agro-anatomic traits and QTLs influencing oil SC of selected kenaf accessions were investigated. Seeds of eighteen kenaf accessions: NHC(11)1, NHC(12)1, NHC10(2), NHC12(2), NHC13(1), NHC13(2), NHC14(2)2, NHC2(1)a, NHC4(1), NHC4(2), NHC4(2)a, NHC5(1), NHC5(2), NHC6, NHC7, NHC8(1), NHC8(2) and NHC9(2) were randomly selected and sown in a Randomised Complete Block Design (RCBD, r=3) and harvested at maturity. The respective core and bast Fibre Length (FL-mm) were assessed using eyepiece graticules under a microscope. Plant Height (PH-cm), Fresh Core Mass (FCM-g), Fresh Bast Mass (FBM-g), Dry Core Mass (DCM-g) and Dry Bast Mass (DBM-g) were determined. Ploidy level of each accession was determined using standard procedures. From each accession, one gramme of the sorbents: Ground Bast-GB, Ground Rough Core-GRC, Ground Core Powder-GCP, GCP+GB and GRC+GB (1:1) was immersed in 20 g of crude oil, desorbed and reused once to determine the total sorption capacity (TSC-g/g). The treatments were arranged in a completely randomised design (r=3). Two accessions with extreme contrasting TSC and their F2 progenies (n=72) were subjected to linkage and QTL analyses. In another experiment, the accessions were grown in RCBD (r=3) for 90 and 150 days to determine the phenotypic phase with higher SC. Data were analysed using descriptive statistics, Principal Component (PC) analysis and ANOVA at α0.05. The core and bast FL, ranged from 0.71±0.20 [NHC12(2)] to 1.43±1.03 [NHC4(2)] and 1.96±0.62 [NHC7] to 2.66±0.69 [NHC9(2)], respectively. The NHC5(2) had higher PH (299.93±6.79) than NHC6 (273.62±5.54), NHC(12)1 (262.47±14.63) and NHC13(2) [28.97±0.58]. The FCM of 52.83±3.11 (NHC14(2)2) was significantly higher than 21.42±3.67 (NHC(12)1) and 20.90±2.87 ([NHC5(1)]), while NHC13(2) had higher FBM (46.13±3.77) than NHC10(2) [30.09±2.68], and 8.92±0.67 [NHC8(1)]. The DCM of 31.69±0.78 [NHC13(1)] was higher than 23.75±0.18 [NHC8(2)] and 6.65±0.01 [NHC5(1)], while DBM of 14.32±8.79 [NHC4(2)] was higher than 9.52±0.82 [NHC12(2)], 9.19±0.54 [NHC14(2)2] and 1.99±0.29 [NHC8(1)]. The TSC ranged from 4.12±0.65 in GCP of NHC8(1) to 13.15±1.18 of NHC7 in GRC+GB. The accessions were grouped into two PC: DCM (45.5%) and FBM (43.9%) in PC1; and core FL (38.7%) and PH (38.1%) in PC2. The ploidy level, alongside 18 linkage groups revealed all accessions as diploid (2n=36). Three major and eight minor QTLs were linked to TSC. The SC decreased with age as 8.18±2.92 (90 days) was higher than 7.64±2.47 (150 days). Dry core mass, fresh bast mass, core fibre length and plant height as well as three major and eight minor quantitative traits loci influenced kenaf sorption capacity. Combination of ground rough core and ground bast of NHC7 had superior total sorption capacity.