EFFECTS OF BLENDED (NPSB) FERTILIZER RATES ON YIELD AND YIELD COMPONENTS OF BREAD WHEAT (Triticum aestivum L.) VARIETIES IN HULBAREG DISTRICT, SOUTHERN ETHIOPIA

Low soil fertility and poor crop management practices are among the major constraints limiting the productivity of bread wheat in Ethiopia in general and Hulbareg District in particular. Therefore, a field experiment was conducted in Hulbareg District during the 2019 main cropping season to evaluate the effect of blended NPSB fertilizer rates on yield and yield components and to determine the economically feasible rates for bread wheat production. Factorial combination of three improved bread wheat varieties (Ogolcho,Kekeba and Kingbird) and five rates of NPSB fertilizers (0,50,100,150 and 200) were laid out in randomized complete block design with three replications. The results revealed that the spike length, plant height, thousand kernels weight, above ground dry biomass, grain yield and straw yield were significantly (P < 0.01 ) affected by the main effects of NPSB and variety. The maximum spike length (8.11 cm) and total dry biomass yield (15389 kg ha-1) were obtained at the NPSB rate of 200 kg ha-1. The interaction of fertilizer and variety also significantly affected grain yield, days to physiological maturity and above ground dry biomass yield. The maximum grain yield (6500 kg ha-1), above ground dry biomass kg ha-1 (15389), were recorded at combination of the highest rates of NPSB i.e 200 kg NPSB with variety Ogolcho. In general, the economic feasibility of the fertilizer over varieties combination indicated that application of 200 kg NPSB ha-1 to Kekeba variety resulted in maximum marginal rates of return of 4202 % . The partial budget analysis revealed that the highest net return (72495 Birr ha-1) with MRR 2711.9% was obtained for Ogolcho from application of 200 kg NPSB ha-1. Based on the result of this study, it can be tentatively concluded that bread wheat variety Ogolcho and NPSB rate of 200 kg ha-1 to be appropriate for bread wheat production in the study area.