Nitrogen nutrition of rice plants measured by growth and nutrient content in pot experiments. 1. Ionic balance and selective uptake.

Abstract

Rice cv. IR5 was grown in sand culture at various levels of NO3, NH4 and K. Complete analysis for major ionic constituents showed that both plant weight and carboxylate content were reduced by K shortage. At the highest KNO3 level, substituting NH4 for NO3 and supplying K as K2SO4 decreased the carboxylate level from 1000 meq/kg DM to 800 meq/kg and resulted in a further increase in plant weight and tiller number/plant. It was concluded that the level of carboxylates permitting maximum growth was exceeded where NO3 was the N source, and that the preference of rice for NH4 was related to the reduced rate of carboxylate production. The situation was considered to be analogous to lime-induced chlorosis. (Abstract retrieved from CAB Abstracts by CABI’s permission)