Effect of Plant Population and NPS Fertilizer Rates on Yield and Yield Components of Mung Bean (Vigna radiata L. Wilczek) in Bako, Western Ethiopia

Mung bean (Vigna radiata L.) is a pulse crop with multiple uses and it was introduced recently in the study area. However, its productivity is limited by inadequate plant population and NPS fertilizer rate in the study area. Hence, this study was carried out to determine optimum plant population and NPS fertilizer rates for mung bean borda varaity in Bako, Western Ethiopia. The experiment comprised of factorial combinations of four different plant populations (500000, 571429, 666667, and 800000 plants ha-1) and five NPS fertilizer rates (0, 50, 100, 150 and 200 kg ha-1) and it was laid out using Randomised Complete Block Design with three replications. The results indicated that main effect of plant population and NPS fertilizer rates had significant effect on phenology, growth, yield, and yield components of mung bean, except stand count, above-ground biomass, straw and seed yield, which were affected by the main factors and their interactions. Highest nodule dry weight per plant (0.14g), number of pods per plant (4.74g), seeds per pod (10.26g), 100-seed weight (3.61g), and harvest index (31.16%) were observed under minimum plant population (500,000 plants ha-1). Moreover, the highest days for 50% flowering (49.08 days), 90% physiological maturity (64.5 days), effective nodules per plant (2.28),nodule fresh weight (0.33gm), nodule dry weight (0.141g plant-1),plant height (11.10cm), number of leaves per plant (8.80), number of branches per plant (3.11), tap root length (8.99cm), number of pods per plant (4.79), seeds per pod (10.78g), 100-seed weight (3.73) and harvest index (32.98%) were observed under 200 kg ha-1 NPS fertilizer. The highest stand count per hectare (780,667 plants ha−1), above-ground biomass (4,947kg ha-1), seed yield ha-1 (1,371kg ha-1) and straw yield (3,575 kg ha-1) were recorded at higher plant population (800,000 plants ha-1) with 200kg NPS ha-1 fertilizer rate (kg ha-1). However, higher plant population (800,000 plants ha-1) at the rate of 100 kg NPS ha-1fertilizer produced 1,325 kg ha-1seed yield which was the highest net benefit (50,080 ETB) and marginal rate of returns (5,610.8%). Therefore, application of 100 kg NPS ha-1 fertilizer rate with plant population of 800,000 plants ha-1 can be recommended for mung bean production in the study area and similar agro-ecologes. However, the current study was carried out only in one location for one cropping season, hence further studies over many seasons and across several locations are needed to have a conclusive recommendation for wide range of agro ecologies for mung bean production.