INCREASING GRAIN YIELD OF SUBMERGENCE-TOLERANT RICE (ORYZA SATIVA L.) THROUGH APPROPRIATE NUTRIENT MANAGEMENT

Flooding is one of the environmental stresses that cause a reduction in rice yield and the effect varies between rice varieties. This study aimed to investigate the response of different rice varieties (Hnan Gar, Swarna-Subl, Bio-6, and Bio-8) to the application of various combinations of nutrient doses (110:0:75, 110:50:0, 110:50:75, 110:80:75 and 110:50:110 of N:P205:K20 kg ha(-1)) under natural submergence conditions in Myanmar. The survival percentages of the different rice genotypes were found not to be significantly varied after 20 days of submergence. Swarna-Subl and Bio-8 produced lower underwater shoot elongation, which tended to save energy to be used for later growth, and this resiliency contributed to higher grain yield. Varying the fertilizer application rates produced no significant effect on the percentage of shoot elongation. The Swarna-Sub 1 and Bio-8 varieties produced much higher yields compared to Hnan Gar and Bio-6 as a result of a higher filled grain percentage and panicle number m-2. In addition, fertilizing with a dosage of 110:50:110 kg ha-1 (N:P2O5:K2O) provided better crop performance and higher yield. These results demonstrate that appropriate nutrient management by combining tolerant varieties is able to help in the mitigation of the adverse effect of submergence stress.