RESPONSE OF COMMON BEAN (Phaseolus vulgaris L.) VARIETIES TO PHOSPHORUS FERTILIZER RATES AT HARAMAYA, EASTERN ETHIOPIA

Common bean is one of the most economically important pulse crops cultivated in eastern Ethiopia. However, its average yield reported at national level remains far below the potential yield to be attained. This is partly due to low soil fertility management and inappropriate agronomic packages. Hence, this experiment was conducted to assess the effect of phosphorous rates on growth, yield and yield components of improved common bean varieties and to estimate the cost benefit of Phosphorous rates for production in eastern Ethiopia. The experiment was conducted in Haramaya University, Rare during 2018 to 2019 main cropping seasons. Five rates of Phosphorous (0, 15, 30, 45 and 60 kg ha-1) and three varieties of common bean (Fadis, Tinike and Hirna) in factorial combinations were laid out in randomized complete block design with three replications. Data on phonological, growth and yield and yield related components were collected and analyzed. The result showed that the interaction of variety x P had no significant on all traits. However, varieties significantly varied in days to 50% flowering, 95% maturity, plant height, number of primary branches, seed per pod, specific leaf area, total biomass yield and seed yield, but not in days to emergence, leaf area, leaf area index, hundred seed weight and harvest index. Variety Hirna was the earliest days to flowering (56 days) and maturity (110 days). It had the highest plant height (49.51cm2), seed per pod (5.85), specific leaf area (163.19cm2 g-1), total biomass yield (5062.5 kg ha-1) and highest seed yield (2875 kg ha-1) while highest number of primary branch obtained from Fadis (3.69) . The main effect of phosphorous application rate had significant effect on almost all parameters except days to emergence, plant height and harvest index. The earliest days to flowering (54 days), maximum number of primary branch (3.85), total nodule number (56.26), effective nodule number (47.20), specific leaf area (178.70cm2g-1), number of pod per plant (12.16), number of seed per pod(5.92) and highest grain yield (2875 kg ha-1) were obtained from 30 kg P ha-1application. However, the earliest days to maturity (108days), maximum leaf area (1406.74 cm2) and leaf area index (3.52) registered from 60 kg P ha-1 and seed per pod and total biomass yield (5006.9kg ha-1) from 45 kg P ha-1. The highest net benefit (26512.47ETB ha-1) was obtained from combination of variety Hirna with application of 30 kg P ha-1. Thus, it can be concluded that the combination of Hirna variety with application of 30 kg P ha-1 to be proved superior with respect to economic advantage.