Assessing Deepwater Rice Mutant Populations for Some Morpho-Physiological and Agronomic Traits

Abstract

Unlike most current rice cultivars, rice produced in the deepwater habitat may live for at least a month in water depths exceeding 50 cm. In this experiment, 30 M6 populations developed by irradiation of Laksmidigha rice seeds utilizing 200 Gy dose of gamma rays were assessed based on morpho-physiological and agronomic traits. Six mutant populations exhibited noticeably longer leaves, with LD-200-1-1-2-6 being the only mutant population to have noticeably more grain weight/hill than the parent. But none of the mutant populations had significantly wider leaf breadth at any of the three points of the flag leaf and average as well. Six mutant populations LD-200-1-3-3-3, LD-200-1-3-3-4, LD-200-1-3-3-5, LD-200-1-3-2-1, LD-200-1-1-2-1 and LD-200-1-1-2-6 produced significantly higher grain yield/hill which also had significantly longer panicle lengths, internode lengths and heavier 1000-grain weight than the parent. It was discovered through a correlation analysis that grain weight/hill was positively and significantly connected with panicle length and 1000-grain weight, whereas its association with internode distance was positively but not significantly correlated. But the correlation of internode distance with 1000-grain weight was significantly positive. The six mutant populations that significantly increased grain yield/hill compared to the parent also had higher levels of total chlorophyll and chlorophyll "a" in their flag leaves. In anatomical studies of roots, it was found that all the 21 cross sections showed damaged cortex with different degrees except LD-200-1-3-3-7 and LD-200-1-1-2-5. Even the parent grown in Chamber-1 showed minimum cortex damage. Also, the grain yield of these two mutant populations did not differ significantly from the parent although chlorophyll “a” and total chlorophyll contents were much higher.