Abstract

Nitrogen is essential due to its function in plant growth and development. It is a component of DNA and proteins which are the building blocks of life. Nitrogen is one of the most limiting factors for crop production. The need to meet the huge nitrogen requirement has necessitated the use of synthetic fertilizer. However, its continued application affects soil health, environment, and agricultural sustainability. Identifying breeding lines and developing new varieties that can efficiently fix atmospheric nitrogen and integrating these varieties into farming systems is one of the best alternatives. Field experiment was conducted at the Savanna Agricultural Research Institute research fields using 20 elite soybean lines under rain fed conditions. The objective was to select soybean (Glycine max) lines for improved nitrogen fixation, water use efficiency and grain yield. Randomized complete block design was used with three replications. Data collected were the amount of nitrogen fixed, nitrogen derived from the atmosphere, and grain yield. Genotypes showed significant variability in the amount of N-fixed, percent nitrogen derived from the atmosphere and grain yield. The mean symbiotic N contribution by the genotypes ranged from 53.6 kg/ha – 370.5 kg/ha. Grain yield was significantly different among the genotypes. Five genotypes showed superior performance for N-fixed and grain yield. There was high heritability, Phenotypic Coefficient of Variation and Genotypic Coefficient of Variation for the selected traits, which is required in breeding program for crop improvement. Genotypes should be re-evaluated in multi-locations to confirm performance and stability for release as varieties.

Key words:  Glycine max, genotypes, heritability, genotypic coefficient of variation, phenotypic coefficient of variation.