PHENOTYPIC AND GENOTYPIC ANALYSIS OF SOME RICE VARIETIES FOR GROWTH AND YIELD TRAITS UNDER STRESS CONDITION

Field experiments including 100 rice genotypes from different sources (selected from local and exotic materials) were carried out as a preliminary screening nursery (PSN) at two locations in Sakha Agriculture Research Station (drought conditions) and at New Valley Agriculture Research Station under heat conditions during 2007 rice growing season. Each genotype was planted in four rows, five meter long and 20  cm a part with three replications, where two the outer rows were used as borders and the two inner rows were used to record the data. The best selected genotypes, under both drought and heat conditions, according to their desirable traits, were evaluated under the same conditions during 2008 and 2009 rice growing seasons. These experiments included 18 and 20 out of 100 rice genotypes under drought and heat conditions, respectively.
The results indicated that, the vegetative characters comprising of days to heading, plant height, tillers number/plant and leaf area. Also, root characters, comprising root length, root volume, root to shoot ratio and roots number/plant, could be considered as parameters related to tolerance. These traits could be used as selection criteria since they helped the plant to maintain a favorable water balance and, hence, controlled, early stomata closure. Analysis of variance showed significant variations among the vegetative and root characters under drought conditions. Heritability estimates were higher for grain yield (0.92), plant height (0.88), leaf area (0.82), number of grains per panicle, root/shoot ratio (0.81) and days to heading (0.88). Consequently, selection for grain yield and its components could be more effective in the selected genotypes under drought and heat conditions.