Water management and liming in relation to grain yield and iron toxicity in rice

Abstract

Two types of soil collected in the "Zona da Mata" region of Minas Gerais, Brazil, were subjected to different water management regimes and liming, in order to study the effect on grain yield, nutrient absorption and iron toxicity in rice (Oryza sativa L.) cultivar BR IRGA-409. The lay-out was split-plot with plots arranged in a randomized complete block design and three replications. Evaluation was made of growth, nutrient absorption and grain yield. Leopoldina soil (SL) produced plants with increased tiller number and root length besides relatively high dry matter and grain yield per pot when compared to Muriaé soil (SM), in anaerobic condition. The same was not observed under aerobic condition. The effect of iron toxicity was indirect resulting in decreased absorption of macro and micronutrients. The iron toxicity level was greatly influenced by plant nutritional balance. Symptoms were evident 25 days after transplanting, due to a relatively high quantity of iron in SM soil. The characteristic toxicity symptoms consisted of yellowing of lower leaves at the beginning, and subsequent increase to top young leaves. Also, the roots were covered with a layer of ferrous oxide.