Dual Inoculation of Native Rhizobium spp. and Arbuscular Mycorrhizal Fungi: An Impact Study for Enhancement of Pulse Production

Fifteen Rhizobium spp. from nodules of 6 common pulses collected from 6 districts of Assam were studied for their infectivity, intrinsic antibiotic resistance, nitrogenase activity and effect of dual inoculation with two native Arbuscular Mycorrhizal Fungi viz. Glomus mosseae(GM) and Gigaspora gilmarie(GG). Out of the 15 isolates 9 were found nodulation positive and 6 of them(AR1, BR8, BR12, AR10, UR10 & GR21) were subjected to intrinsic antibiotic sensitivity test of which AR1 showed resistance against all the 9 test antibiotics. Isolates AR1 and GR21 showed the highest(4.25 mole, $gm^{-1}hour^{-1}$) and the lowest(1.05 mole, $gm^{-1}hour^{-1}$) nitrogenase activity respectively. In Most Probable Number count, the maximum Rhizobium population $5.8{\times}10^5$, was found in both Blackgram and Greengram variety of pulses. The maximum dry weight of nodules(3.14 g), dry weight of shoot(10.08 g), nitrogen content(7.68 mg, $plant^{-1}$), chlorophyll content(1.89 mg, $g^{-1}$), phosphorus content of shoot(6.17 mg, $g^{-1}$) and yield(535.67 kg, $Ha^{-1}$) were found when AR1 dually inoculated with GM in Blackgram.