Legume Crops and Nitrogen Fixing Bacteria in Barind Tract

Abstract

Legume Crops and Nitrogen Fixing Bacteria in Barind Tract Studies were undertaken to isolate, screen and characterize rhizobial bacteria from 12 different pulse legumes grown at different locations of Barind tract. Thirty-one rhizobial cultures were isolated and characterized through morphological and biochemical• investigation. Screening of the isolates of black gram, mungbean, chickpea and soybean were done through pot culture and field trial. Pot cultures were conducted in green house at Bangladesh Institute of Nuclear Agriculture (BINA), Mymensingh during October, 2002 to April 2003 and field trials were carried out at the farm of Rural Development Academy, Bogra from October 2003 to April 2005. The treatments were inoculant 11, 12 hand 13 as single culture and their mixed culture in presence and absence of different fertilizers and their mixture. Fertilizer nutrients P, S, B, Mo and their mixture were used @ 15, l0, I and 0.5 kg/ha in black gram and mungbean, 25. 20. I and I kg/ha in chickpea and 30, 20, 1.5 and I kg/ha in soybean both in pot culture and 1st field experiment. In 2nd field experiment N treatments were @ 20 and 40 kg /ha for all crops, P, K and S were used as basal dose @ 25, 20 and 20 kg/ha in black gram and mungbean and @ 30, 20 and 30 kg /ha, respectively in chickpea and soybean. It was observed from the experiment that rhizobial inoculation either alone or in presence of P, S, B, Mo and N fertilizer increased plant height, tap root length, shoot and root dry weight, nodule number and dry weight, pod/plant, seed/pod,1000 seed weight, seed and hay yield, and N and P uptake in seed and hay significantly compared to uninoculated controls. No nodules were formed on the uninoculated soybean plant both in pot and field experiments. Differences were found among the treatments. In pot culture and field experiment inoculants + mixed fertilizer performed the highest results in all the parameter studied except shoot dry weight in mungbean, shoot and nodule dry weight, number of effective nodules, pod number, 1000 seed weight and hay yield in chickpea and plant height and shoot dry weight in soybean in field experiment. The single fertilizer treatment P also showed the significant effect on some of the parameters studied and it gave the highest values on 1000 seed weight of black gram, nodule dry weight of mungbean and root dry weight or soybean in pot culture pod number per plant of chickpea and seed number per pod of soybean in field experiment. Integrated use of inoculants and nitrogen were found to be more effective and beneficial compared to their individual application for pulse cultivation in Barind tract. In field experiment mixed culture inoculant + 20 kg N/ha gave the highest value in all the parameters studied. Application of 20 kg N/ha enhanced inoculant response to the experimental crops and 40 kg N/ha was inferior to control in some cases. Study on several carrier materials (peat, press mud and clay soil) with three different Brady rhizobium and one Mesorhizobium isolates showed that peat was the best carrier for the production of rhizobial inoculants. The study clearly indicated a great prospect or rhizobial inoculation with nitrogen in pulse cultivation in Barind tract.