Abstract

Recently Green bean production and demand is increasing in Ethiopia due to its fast maturity and nutritional value. However, various constraints are reported for its low productivity, including inappropriate uses of plant population and fertilizer rates. The objective of this study was to determine the optimum plant population and NPS rate for quality and economically feasible yield of Green bean. The experiment was conducted in field conditions at Alage, Central Rift Valley of Ethiopia, under supplemental irrigation in 2019. A factorial combinations of three plant populations (222222, 250000 and 333333 plants ha-1) and five levels of blended NPS (0, 132, 142, 152 and 162 kg NPS ha-1) were used in a randomized complete block design (RCBD) with three replications. Number of nodules per plant, number of effective nodule per plant, number of leaf per plant, plant height, and number of branches per plant, number of pod per plant, total above ground fresh biomass, pod diameter, pod length, harvest index and yield per plant and per hectare were recorded. All parameters were subjected to analysis of variance.  The least significant differences (LSD) at the level of 5% significance were used to compare the treatments mean. The results showed that plant population and NPS rates had significant effects on  number of nodules, number of leaf, number of branch, plant height, number of pod, pod length, harvest index, yield per plant and per hectare. The highest Green bean yield of 13.75 tons ha-1 and 16.06 tons ha-1 was obtained at the highest plant population (333333 plants ha-1) and the highest NPS rate (162 kg NPS ha-1), respectively. The highest acceptable marginal rates of return (57349%) and (6997.2%) were obtained from 333333 plants ha-1 and 162kg NPS ha-1, respectively. Thus, it can be concluded that 333333 plants ha-1 and application of 162kg NPS ha-1 were gained the superiority for both agronomic and economic growth and productivity for plati variety of Green bean under supplementary irrigation at Alage area.

Key words: Green bean, plant population, NPS fertilizer rate, growth, yield.