EFFECT OF BLENDED NPS AND N FERTILIZER RATES ON YIELD COMPONENTS, YIELD AND GRAIN PROTEIN CONTENT OF BREAD WHEAT (Triticum aestivum L.) IN BORE DISTRICT, GUJI ZONE, SOUTHERN ETHIOPIA

Bread wheat is a major cereal crop in Ethiopia and in the study area, but its yield is limited due to minimum use of improved varieties, diseases, weeds, low soil fertility and lack of location specific fertilizer recommendation. Therefore, a field experiment was conducted during the 2016 main cropping season at Bore Agricultural Research Center to evaluate the effect of blended NPS and N fertilizer rates on yield components, yield and grain protein content; and to determine economically appropriate rates of blended NPS and N fertilizers for bread wheat production. The treatments consisted of four levels of NPS (50, 100, 150 and 200 kg NPS ha-1) and four levels of N (23, 46, 69 and 92 kg N ha-1) including one control (0 NPS and 0N). The experiment was laid out as a Randomized Complete Block Design in a factorial arrangement with three replications. Analysis of the results revealed that days to 90% maturity (DTM), grain protein content (GPC) and spike length (SL) were significantly affected by the main effect of NPS as well as the main effect of N while thousand kernel weight (TKW), hectoliter weight (HLW), plant height (PH) and number of productive tillers (NPT) were significantly affected only by the main effect of N. The maximum DTM (167.6 days), GPC (11.24%) and SL (8.43 cm) were recorded at NPS rate of 150, 200 and 200 kg ha-1, respectively. Similarly, the maximum DTM (166.8 days), GPC (11.35%) and SL (8.49 cm) were recorded at the highest rate of N (92 kg N ha-1). Thus, as the rates of NPS and N increased, the DTM, GPC and SL were increased. Likewise, the maximum TKW (44.13 g), HLW (84.25 kg hl-1), PH (94.03 cm) and NPT (271.1 m-2) were obtained at the highest rate of N (92 kg N ha-1). The interaction of the two fertilizers also significantly affected the above ground dry biomass (AGDB), days to heading (DTH), grain yield (GY), harvesting index (HI), number of kernels per spike (NKPS), number of tillers per plant (NTPP) and straw yield (SY). The highest AGDB (18.87 t ha-1), DTH (83.67 days), GY (7.65 t ha-1), NTPP (3.76) and SY (11.218 t ha-1) were recorded at combined application of 200 kg NPS + 92 kg N ha-1. However, the result of economic analysis showed that combined application of 100 kg NPS and 92 kg N ha-1 gave economic benefit of 42272.5 Birr ha-1 with the marginal rate of return 1728.3%. Therefore, use of 100 kg NPS and 92 kg N ha-1 can be tentatively recommended for production of bread wheat in the study area. Further research work over season and year would be recommended for the study area.