Effects of exogenous nitrogen-compounds on the concentrations of allantoin and various constituents in several organs of soybean plants

Abstract

The effects of nitrogen compounds supplied to culture solutions on the concentrations of allantoin and various constituents in several organs of soybean plants A62-1 (nodulating variety) were studied to elucidate the symbiotic relation. A62-1 plants bearing well developed nodules accumulated a large quantity of allantoin in the upper stems, roots, developing leaves, pods and maturing seeds in the reproductive stage. However, the addition of N lowered the allantoin accumulation without changing the soluble Kjeldahl-N concentration in any organs of the host plants. Also addition of N increased the amino-N concentration in upper stems and roots in contrast with the lack of change in developing leaves, pods and maturing seeds. The decrease of allantoin accumulation was parallel with the weakened formation of nodules. The addition of N also scarcely affected the concentrations of reducing sugar and sugar in the upper stems. There were few differences in the concentrations of allantoin, amino-N and soluble Kjeldahl-N among nodules attached to the A62-1 plants grown in various amounts of nitrate. Statistical calculations showed that the allantoin concentration in A62-1 plants was correlated negatively with N application and positively with nodule weights. Significant levels of both correlation coefficients were attained in the reproductive stage.The variation in allantoin concentration in A62-1 plants was not correlated with that in the sugar/soluble Kjeldahl-N ratio and the reducing sugar/soluble Kjeldahl-N ratio. A large quantity of nitrate added to the nutrient solutions of the A62-2 (non-nodulating variety) plants elicited only a small amount of allantoin accumulation in the upper stems, with a consequent increase in the concentrations of amino-N and soluble Kjeldahl-N and a decrease in the concentrations of sugar and reducing sugar.