Response of Seed Size and Plant Density on Growth, Yield and Grain Quality of Bread Wheat (Triticum aestivum L.) Varieties Under Vertic Luvisols of Kulumsa in Arsi Zone

With November the objectives of to determine the optimum plant density levels of bread wheat by identifying the most cost-effective variety, a field experiment was conducted at Kulumsa Agricultural Research Center from June to 2018 cropping season, Three bread wheat varieties (Hidassie, Dendea and Shorima) representing different seed sizes of large, medium, small, respectively and four plant density levels of 250, 300, 350 and 400 plants m-2 were tested. The main effect of the varieties seed size on days to 50% of heading, days to 90% of maturity, thousand kernel weight and hecto liter weight showed significant (p<0.01) variations, while number of tillers and spike length indicated statistically significant (p<0.05) variations. The use of 300 plants m-2 plant density for the variety Hidassie /large seed size/ resulted in highest seedling number (26.30), of tillers (7.50), days to 50% of heading (63.00), days to 50% of maturity, (116.00), spike length, (7.50 cm), thousand kernel weight (48.22 gm.), hecto liter weight (78.30 kg/hL). The main effect of plant population on number of seedlings and harvest index showed significant (p<0.01) variations. Number of seedlings and harvest index resulted in (25.31) and (44.05) respectively. The interaction effects of variety and plant density on harvest index, indicated significant (p<0.001) variation, while grain yield showed statistically significant (p<0.01) variation, likewise biomass yield and straw yield indicated significant (p<0.05) variations. The harvest index, resulted in (43.63%), while grain yield is (4.309 Ton ha-1), similarly biomass yield and straw yield are (11.00 Ton ha-1) and (5.28 Ton ha-1) respectively, and it suggests that these traits are generally enhanced by the genetic makeups of the variety Hidassie /large seed size/. Economic analysis using partial budget procedure was performed on grain yields to determine the treatment with most profitable returns. The beneficial marginal rate of return (8.50) and benefit cost ratio (8.07) was obtained from the variety Hidassie /large seed size/ at a plant density of 300 seeds m-2 followed by a marginal rate of return (9.55) and benefit cost ratio (8.05) were also recorded again from the variety Hidassie /large seed size/ at plant density of 250 plants m-2. So the most cost-effective variety and plant density level for farmers with low cost of production and higher benefits were identified to be the variety Hidassie /large seed size/ at the plant density level of 300 plants m-2 in the rain fed cropping season is identified as low cost of production with highest benefit and can be recommended for the producers of wheat crop. The plant density level of 250 plants m-2 for variety Hidassie /large seed size/ was also cost-effective with highest net-benefit and can be recommended as another possible choice. But, as this study was conducted at one experimental site, it is required to repeat the experiment across locations, soil type, and over-seasons to make agronomically consistent recommendations and economically feasible levels of plant density for bread wheat. Keywords: Bread Wheat Yield, Economic Benefit, Plant Density, Grain Quality, Varieties Seed Size. DOI: 10.7176/JNSR/11-15-01 Publication date:August 31st 202