Abstract:
Wheat (Triticum aestivum L.) is a major cereal crop and is a stable food for about one third of the world population and Ethiopia is the second producer in sub Saharan Africa (SAS). Bread wheat is produced in Mecha Disrict, North Western Ethiopia, where its production and productivity is very low due to the use of inappropriate rates of seeding and nitrogen fertilizer. Soil fertility decline and non optimal use of N and seeding rates are the principal factors to low productivity of crop and food insecurity in Ethiopia. Therefore, a field experiment was conducted at Koga, a research site of Bahir Dar University at 2019/2020 cropping season with the objectives of investigating the effects of seeding rates and rates of N fertilizer application on yield and yield components of bread wheat and to determine the optimum N fertilizer and seed rates for economical optimum yield of bread wheat in the study area under rain fed conditions. An experiment was laid out in Randomized Complete Block Design (RCBD) with three replications in factorial arrangement of three different seeding rates (125, 150 and 175 kg ha-1) and four nitrogen levels (0, 46, 92 and 138 kg ha-1). The results of the experiment showed that earlier very highly significant (P<0.001) days to 90% physiological maturity were obtained from both 175 kg ha-1seeding and 92 kg ha-1 N rates, while it becomes late both at 125 kg ha-1 seeding and 0 kg ha-1 N rates. The highest number of very highly significantly (P<0.001) total tillers (2.03) and significantly (P<0.05) effective tillers (1.70) per plant was obtained at the combination of 125 kg ha-1 seeding rates with 138 kg ha-1 N rates, while the lowest number of total tillers (0.93) and effective tillers (0.43) per plant at 175 kg ha-1 seed with 0 N rates. Highly significant (P<0.01) tallest plant height (69.02 cm) and shortest plant height (66.83 cm) was recorded from 175 and 125 kg ha-1 seeding rates, respectively. Very highly significant (P<0.001) tallest plant height (72.49 cm) and shortest plant height (62.70) was recorded from 138 and 0 kg ha-1 N rates, respectively. Spike length, number of spikelets and number of kernels per spike were very highly significantly (P<0.001) increased as seeding rate decreases from 175 to 125 kg ha-1 and increasing of N from 0 to 138 kg ha-1. Significantly (P<0.05) highest grain yield (2.91 t ha-1) and lowest grain yield (2.47 t ha-1) were recorded from 150 and 125 kg ha-1 seeding rates, respectively. Very highly significant (P<0.001) highest grain yield (3.21 t ha-1) and lowest grain yield (1.84 t ha-1) were recorded from 138 and 0 kg ha-1 N rates, respectively. The present research finding showed that using of 150 kg ha-1 seeding rate and application of 138 kg ha-1 N or 261 kg ha-1 urea fertilizer rate were recommended for study area based on their maximum grain yield. The result of economic analysis showed that the maximum net benefit (ETB 31,516.7ha-1) with a maximum MRR % (1020%) was obtained from a combination of 150 kg ha-1 seeding rates with 138 kg ha-1nitrogen fertilizer rates. However, to make reliable and acceptable recommendation similar experiment has to be repeated over locations and seasons of the district with the inclusion of more nitrogen rates and seeding rate.
Keywords: Bread wheat, Grain yield, Nitrogen levels, Seeding rates, Yield components.