Effects of inter-row spacing on growth, seed yield and yield components of Soybean (Glycine max) in Makurdi, Benue State-Nigeria

Abstract

Despite the numerous benefits of soybean, its grain yield per unit area in Nigeria is low estimated at 1.2 tons ha-1 compared to the worldwide average yield of 2.5 tons per hectare. The low yield is due in part to limited use of phosphorous fertilizer and poor crop management practices including low plant populations. Farmers in northern Nigeria including Benue State sow seeds in rows spaced 75cm. There has been little recommendation as to the exact row spacing that will give higher yield in soybean especially in Benue State. It is this gap that this research work seeks to address. This study was designed to determine the effects of row spacing on agronomic traits and yield of soybean in Makurdi, Benue state. The experiment was a 2 (row spacing) x 6 (soybean varieties) factorial arrangement laid out in a Randomized Complete Block Design (RCBD) with three replications.

Data collected were subjected to Analysis of variance (ANOVA) and treatments means were separated using Duncan’s Multiple Range Test (DMRT) at 5% and 1% level of probability. Also cost benefit ratio (CBR) was calculated as gross return divided by cost of production. This study shows that reducing row spacing or plant population from 75cm x 10cm to 50 cm x 10 cm significantly increased the plant height from 67.24 to 72.07cm. Meanwhile, it reduced the number of branches per plant from 7.37 to 5.01 and number of pods per plant from 55.90 to 49.69 pods. With respect to varieties, TGX-1951-4F, TGX-1951-3F and TGX-1945-1F had the highest grain yield of 3.9, 3.5 and 3.5 tons per hectare respectively as compared to other varieties which had lower yields. Cost Benefit Ratio (CBR) showed high advantage in growing soybean at 50cm inter-row spacing than at 75cm interrow spacing. Therefore, grain yield in soybean is largely a function of plant population per m2. To increase soybean productivity in Makurdi Benue State of Nigeria, it is recommended that closer row spacing of 50cm x 10cm should be adopted for the soybean varieties tested.