| Abstract: | The effect of water regimes and soil moisture stress on total nodule number, effective nodule number, nodule dry weight, nitrogenase activity and nitrogen fixation in soybean was studied. The effective nodule number, nodule weight, nitrogenase activity and nitrogen fixation increased due to increase in water regimes from 0.4 to 0.6 Cumulative Pan Evaporation (CPE). The stress during either flowering or pod filling reduced the effective nodule number, nodule weight, nitrogenase activity and nitrogen fixation. The amount of nitrogen fixed was maximum with 0.8 CPE (50.09 kg ha-1 season-1) followed by 0.6 CPE (42.08 kg ha-1 season-1) and 0.4 CPE (33.04 kg ha-1 season-1). The amount of nitrogen fixed was reduced by 17.71 % and 26.39 % due to stress during flowering and pod filling respectively compared to normal irrigation. |
