Submergence induced tiller mortality and yield reduction in rice can be minimized through post-submergence nitrogen application.

Abstract

The main strategies enabling rice plants to cope up with flash flooding stress require growth regulation during submergence and subsequent rapid growth recovery after de-submergence and better nutrient management options can enhance this strategy. Application methods of nitrogen and phosphorus were evaluated in submerged rice for tiller mortality, productivity, grain quality and nutrient absorption. The performance of Sub1 (IR-64 Sub1 and Swarna Sub1) and non-Sub1 (IR-20) cultivars of rice was tested under clear and turbid water for their tolerance to submergence in response to basal phosphorus and postsubmergence nitrogen. Tillering ability, yield and nutrient absorption of rice subjected to complete submergence for 15 days was decreased significantly over non-submerged rice plants. Turbid water submergence was fatal in terms of tiller mortality, reduced nutrient absorption and yield because of low light and dissolved oxygen underwater. The crop fertilized with nitrogen produced more number of tillers, yield attributes and grain yield than the unfertilized crop under complete submergence at maximum tillering stage, effects were more positive when basal phosphorus was applied with nitrogen. Urea foliar spray after desubmergence significantly enhanced the leaf area, dry matter weight, specific leaf weight, tiller regeneration ability and narrowed down the flowering time which led to higher grain yield and productivity. The findings of the study suggest that higher rice yield can be obtained by adjustment in timing of nutrient application in flood prone areas, where farmers are scared to apply fertilizer because of risk involved.