Assessment of Nitrogen Fixation by Mungbean Genotypes in Different Soil Textures Using 15N Natural Abundance Method

Ensuring food and nutritional security in light of high climate variability and a rapidly growing population remains a challenge. Mungbean ( Vigna radiata (L.) Wilczek) is a short duration, drought-tolerant, and ureide-exporting legume crop capable of symbiotic atmospheric nitrogen fixation. Estimates of biological N 2 fixation by mungbean in different soil textures have not been extensively studied. We conducted this study to evaluate plant growth and N 2 fixation of five mungbean genotypes (Berken, 8735, IC 8972-1, STB#122, 223) inoculated with Bradyrhizobium spp. and grown on loamy sand and silt loam soils under glasshouse conditions. Mungbean dry matter yield, δ 15 N values, shoot content, amounts of N-fixed, and soil N uptake were all higher on the silt loam soil compared to the loamy sand soil, demonstrating the effects of soil properties on plant growth and N 2 fixation potential. Among genotypes, IC 8972-1 produced the highest biomass (7.85 g plant −1 ), shoot N content (200 mg plant −1 ), and soil N uptake (155 mg plant −1 ) than other genotypes. The significant interaction between soil texture and genotypes for root dry matter and %Ndfa indicates the major role of legume root-nodule bacteria in symbiotic N 2 fixation. This study demonstrated that N 2 fixation in mungbean is affected by both genotypes and soil properties, illustrating the need to consider soil properties in order to maximize N contribution from mungbean to agricultural production systems.