EFFECTS OF NPS FERTILIZER RATES ON GROWTH, YIELD COMPONENTS AND YIELD OF COMMON BEAN (Phaseolus vulgaris L.) VARIETIES UNDER IRRIGATION AT GEWANE, NORTH-EASTERN ETHIOPIA

Abstract

Common bean (Phaseolus vulgaris L.) is one of the most important cash crops and source of protein for farmers in many lowlands and mid-altitude area of Ethiopia. However, appropriate management practice that combines high yielding varieties with balanced fertilizers are lacking in the study area under irrigation. Thus, a field experiment was conducted to assess the effects of NPS fertilizer rates on growth, yield components and yield of common bean varieties, and to evaluate cost-benefit of NPS fertilizer rates for production of common bean at Gewane under irrigation. Treatments consisted of factorial combinations of three common bean varieties (Awash-1, Awash-2, and Awash Melka,) with five NPS fertilizer rates (0, 50, 100, 150 and 200 kg ha-1) laid out in Randomized Complete Block Design with three replications. The main effects of NPS fertilizer rates and variety had highly significant (p<0.01) effects on days to 50% flowering, number of primary branches per plant, above ground dry biomass, seed yield and harvest index. The main effects of NPS fertilizer rates had also significant effects (p<0.05) on days to 90% physiological maturity, leaf area, leaf area index and hundred seed weight. The highest number of primary branches per plant (4.04), leaf area (1405.11cm2), leaf area index (3.51), hundred seeds weight (21.67 g,) above ground dry biomass (7230.2 kg ha-1) and seed yield (2909.60 kg ha-1) were recorded from Awash Melka variety. Similarly, the highest number of primary branches per plant (4.03), leaf area (1421.00 cm2), leaf area index (3.55), hundred seeds weight (20.05 g), above ground dry biomass (7419.0 kg ha-1) and seed yield (3145.00 kg ha-1) were recorded at 200 kg NPS ha-1 fertilizer rate. Interaction of varieties with NPS fertilizer rates showed also highly significantly effects (p<0.01) on number of pods per plant and number of seeds per pod. Where the highest number of pods per plant (28.40), and number of seeds per pod (6.59) were recorded from Awash Melka variety with 200 kg NPS ha-1 fertilizer rate. However, the economic analysis showed that the combination of 150 kg NPS ha-1 with variety Awash Melka gave the highest net-benefit (53947.80 ETB ha-1) with MRR of 1364.17%. Thus, it can be concluded that the use of 150 kg NPS ha-1 with variety Awash Melka to be best for the production of common bean in the study area.