Response of Soybean to Inoculation with Rhizobial Strains: Effect on Growth, Yield, N Uptake and Soil N Status

A field experiment was conducted with ten treatments including nine different soybean rhizobia strains and one un-inoculated control in soybean cv. PK-416 under rain fed condition. The highest increase in plant dry matter and pod yield over control was achieved due to inoculation with strain SB-16. The strains like SB-12, SB-16, SB-102, SB-271 and SB-9 showed consistently better performance in N uptake by shoot and grain at different stages of growth, thus justifying the validity of the parameter to be used as indicator of N fixation 2 efficiency of the inoculated strain. The soil N depleted by 13.4 20.2 per cent in the inoculation treatments and 29.6 per cent in the uninoculated control treatment after cropping of soybean. On the basis of efficiency ratio at 60 DAS the strains SB-12, SB-16, SB-102 and SB-271 were classified as efficient, the strains SB-6, SB-9, SB-120 and SB-294 as moderately efficient and the strain SB-243 was found inefficient with respect to their nitrogen fixation ability.