Understanding Submergence Tolerance of Some Traditional Rice Cultivars at Vegetative Stage

Abstract

Submergence is an important abiotic stress affecting rice cultivation causing yield losses every year. Although, as a semi aquatic plant, rice is generally intolerant to complete submergence, rice plants die within few days when completely submerged. However, varieties tolerant to complete submergence are capable of surviving underwater for about 14 days and recovered after the water recede. This study was conducted to investigate the submergence tolerance in traditional rice cultivars at vegetative stage. Six week old plants were subjected to complete submergence stress for 9 days and 14 days separately. Experiment was conducted according to randomized complete block design with 4 replicates and twenty plants were included in to each replicate. After the complete submergence stress, plants were allowed to recover for 14 days at normal growth conditions. Data were collected on the number of surviving plants, plant height before and after the submergence stress and plant height after the two week recovery period. Out of 20 rice cultivars Muthumanikam (100% ) Jamis Wee (73.0% ), Rajes (93.7% ), Madael Kalutara (71.4% ), Lumbini (80.7% ), and Murunga Wee (96.1% ) recorded more than 70% survival rates at 9 day stress period. A 6-10-37 (89.5% ), Murunga Wee (84.3% ), Lumbini (88.5%), Jamis wee (88.1% ) and Wanni Heenati (70.9% ) recorded more than 70% survival rates at 14 day stress period.There was a negative correlation between height gain during submergence stress versus survival percentage at 14 day submerged plants at vegetative stage but not at 9 day submerged plants