Efficacy of Rhizobia for Improving Photosynthesis, Productivity, and Mineral Nutrition of Maize

Rhizobia respond differently for improving physiology, nutrition, and yield of maize under field conditions. Therefore, in the present study, maize seeds (cv. Neelum) were inoculated with Rhizobium phaseoli (strains RS-1 and RS-3) and Mesorhizobium ciceri (strains RS-8 and RS-12) and sown in fields (sites 1 and 2) having sandy clay loam soil. Plants inoculated with RS-3 showed significant increases in plant height, fresh biomass, cob yield, grain yield, grain P, and shoot K contents, as compared to control at both sites. Whereas RS-1 inoculated plants showed increases in the photosynthetic rate, stomatal conductance, water use efficiency, mesophyll conductance, and intrinsic/photosynthetic water use efficiency compared with control. RS-8 inoculated plants showed highest 1000 grain weight, sub-stomatal conductance and relative water content compared to control. However, the highest amount of crude protein, N in shoot/grain and shoot K contents were recorded due to RS-12 inoculation as compared to un-inoculated control. The findings of the experiments clearly demonstrated higher potential of RS-1 and RS-3 species over RS-8 and RS-12 for improving growth, physiology, and yield of maize plants under field conditions which might be due to a specific compatibility of RS-1 and RS-3 with maize cultivar Neelum, as the strength of association is determined by type and species of plant/bacteria and growth conditions.