Response of Nitrogen Fertilizer and Seed Rates on Growth, Yield and Yield Components of Irrigated Bread Wheat in the lowlands of Eastern and South Eastern of Oromia, Ethiopia

The main factors responsible for low yield are less or more plant population and inadequate crop nutrition. As the plant density increases, the competition for resources especially for nitrogen also increases that badly affects the ultimate yield. Therefore, a field experiment was conducted at five multi-location of lowlands of Oromia in three zones, Bale (Dalomena and Sawena), East Shewa (AdamiTulu and Lume), and East Hararghe (Bedeno) districts in 2020/2021 off-season to investigate the response of nitrogen and seeding rates on the growth, yield and yield components of bread wheat variety under irrigation. The treatments consisted of five rates of nitrogen 0, 23, 46, 69, 92 kg ha-1 and three seed rates (125, 150 and 175 kg/ha) of Kakaba variety. The experiment was laid out as a randomized complete block design in a factorial arrangement and replicated three times. The analysis of variance revealed significant differences in the parameters studied. The results of this study revealed that the soil was improved in little beat in PH, organic carbon, total nitrogen and available phosphorus. The combined effects of nitrogen and seed rates significantly influenced the irrigated bread wheat growth parameters. However, nitrogen had more profound effects in enhancing the growth response of the crop than seeding rates. The combined mean effect of the nitrogen and seed rates was significantly (P < 0.05) influenced days to heading, days to maturity, plant height, spike length, seed per spike, biological yield, grain yield and harvest index, whereas, significantly not influenced total tiller per plant, effective tiller per plant and thousand grain weight. The results showed that the maximum grain yield and harvest index were recorded at a seeding rate of 150 kg ha-1 with nitrogen rates of 92 N ha-1 and also at 125 kg ha-1 and 69kg N ha-1. Biological yield recorded at a seeding rate of 175 kg/ha with nitrogen rates of 69 kg N ha-1. The economic analysis also revealed that for a treatment to be considered worthwhile to farmers (100% marginal rate of return), application of 69 kg N ha-1 with 125 kg seed rate N are profitable and recommended for farmers in the study area and similar agro-ecologies.