Effects of Nitrogen Application on Growth and Yield of Nitrate-Tolerant Mutants of Soybean

A field experiment was conducted using nitrate tolerant mutants of soybean (Glycine max IL.1 Merr.) ntsll16 and nts1007 and its parent cv. Bragg as test crops to study the effects of nitrogen application on growth and yield parameters. Nirtogen was fertilized as ammonium sulfate at the rate of 100 kg N/ha. Samples of each line with and without nitrogen application was harvested at flowering, pod filling and maturity stages. Nts1007 in growth parameters were inferior to Bragg and nts1116. The pod numbers of Bragg and nts1116 at pod filling stage decreased with the application of nitrogen but nts1007 showed no difference. Nts mutants nodulated much more than the parent cultivar Bragg at all growth stages in non-N-applied plants. Nodulation of nts1007 was the highest at all stages in both N- and non-N-applied plants. The nodule size of Bragg was depressed sharply with nitrogen application followed by nts1116. In case of nts1007, however, there was no remarkable difference in the nodule size between N- and non-N-applied plants. The grain and total dry matter production were the highest in Bragg followed by nts1116 and nts1007. Nitrogen application depressed both grain and total dry matter production in Bragg and nts1116 but nts1007 revealed the increased values.