Differential productivity response of rain fed sorghum (Sorghum bicolor L.) genotypes in relation to graded levels of nitrogen in Kellem Wollega zone of Ethiopia, East Africa

Abstract

Field experiment was conducted at Haro Sabu Agricultural Research Center using three sorghum genotypes (Lalo, Chemada and Local) during the rainy cropping season of 2014 with an objective to determine the effect of nitrogen rates on growth and yield parameters of sorghum genotypes. The treatments consisted of factorial combination of four nitrogen rates (0, 46, 92 and 138 kg N ha-1) and three sorghum genotypes (Lalo, Chemada and Local variety) tested in a Randomized Block Design with four replications.The results revealed that there was significant effect of N rates on days to 50% flowering, days to 50% physiological maturity, plant stand, Lodging percentage, leaf area at 90 and 120 DAS, leaf area index, number of green leaves/ plant , biological yield, grain yield, and harvest index. There was significant interaction effect of N rates and sorghum genotypes on most of the parameters studied. Significantly higher grain yield was obtained in response to the application of 92 kg N ha with Lalo genotype, which was comparable with Local variety fertilized with 92kgN/ha. The genotype chamada exhibited response up to 46kgN/ha .The superior productivity performance of genotype Lalo could be attributed to better growth in terms of plant stature, more productive tillers, more assimilatory surface,LAI,1000seed weight, and panicles/plant leading to better harvest index than the other genotypes. Across genotypes, increased N rates delayed flowering, physiological maturity ,increased lodging ,enhanced plant height, tillers /plant, leaf area, panicles /plant, grain yield, harvest index; but showed no discernible influence on leaf number/plant, LAI, and test seed weight.