RESPONSE OF COMMON BEAN (Phaseolus vulgaris L.) VARIETIES TO RATES OF BLENDED NPS FERTILIZER IN ADOLA DISTRICT, SOUTHERN ETHIOPIA

Low soil fertility is one of the production constraints of common bean in the study area. Hence, a field experiment was conducted in Adola sub-site of Bore Agricultural Research Centre during the 2016 main cropping season to assess the effect of blended NPS rates on the yield and yield components of common bean varieties and to identify economically feasible rates of blended NPS that increase the productivity of the common bean varieties. The factors studied were six rates of blended NPS (0, 50, 100, 150, 200 and 250 kg ha-1) that contain 19% N, 38% P2O5 and 7% S and three varieties of common bean (Angar, Ibado and Nasir). These were laid out in a factorial arrangement in randomized complete block design with three replications. Significantly the highest number of primary branches per plant (2.77) and the highest number of total pods per plant (18.52) were recorded at the highest rate of 250 kg NPS ha-1 whereas the highest number of total nodules (80.47) and effective nodules per plant (35.54) were obtained from the application of 200 kg NPS ha-1. Among the varieties, Angar gave significantly the highest number of primary branches per plant (2.55) and number of pods per plant (15.3). The interaction of variety and blended NPS had significant effect on almost all parameters except on the number of total and effective nodules per plant, number of primary branches per plant and number of pods per plant. Significantly highest numbers of days (46.67) to flowering and physiological maturity (99.33 days) were recorded for variety Nasir due to application of 200 kg NPS ha-1 and 250 kg NPS ha-1, respectively. Variety Nasir gave the highest plant height (99.72 cm) with application of 150 kg NPS ha-1 while Ibado with application rate of 200 kg blended NPS ha-1 had the highest hundred seed weight (54.33 g). The highest above-ground dry biomass yield (10278 kg ha-1) and the highest harvest index (0.44) were recorded for variety Angar due to the application of 250 kg NPS ha -1 and 150 kg NPS ha,-1 respectively. The highest grain yield (3260 kg ha-1) was recorded for variety Angar at 250 kg NPS ha-1. However, the highest net benefit (29,825 Birr ha-1) was obtained from combination of variety Ibado with application 200 kg ha-1 of blended NPS. Thus, it can be concluded that combined application of 200 kg ha-1 of blended NPS with variety Ibado proved to be superior with respect to economic advantage. However, since the experiment was conducted for one season at one location, the experiment has to be repeated over seasons and locations to make a conclusive recommendation