Asparagine test in relation with the nitrogen nutritional status of crop plants III

During the course of the previous studies (1, 2) of this series dynamics of asparagine appearance in crop plants was investigated and it was found that its appearance has, definitely, direct relation with the nitrogen nutritional status of crop plants. It was also clarified that its appearance is initiated, mostly, by the starting of the panicle formation and the resultant breaking down and transportation of complex nitrogenous compounds. The simultaneous study of asparagine and nitrate appearance revealed that the nitrate has no direct relation with the panicle formation and asparagine appearance. In the first experiment on rice, we did not try nitrate test together with the asparagine test. The surface layer (less than 1 cm) of the rice soil, even in the waterlogged condition gets oxidised gradually and nitrogen exists mainly as nitrate. Moreover, there has been some mention that the rice roots possess an oxidative atmosphere (3,4,5) around it and soils having less amount of easily decomposable organic matter or high water percolating capacity do not get completely reduced under waterlogging, it is supposed that nitrate which is by nitrification from ammonia may appear specially around the roots. It seemed necessary to include nitrate test in this experiment along with the asparagine test. In addition, to study the role of different sources of nitrogen towards the appearance of asparagine, the experiment was designed to have provision of topdressing in the NH⁴, NH⁴+NO³, NO³ and urea forms. It is expected that the result on the topdressing would bring more and more practicality to the asparagine test.