Effect of Soil Water Deficit on Yield and Its Components at The Different Growth Stages in Rice (Oryza sativa)

TWENTY FIVE rice (Oryza sativa) genotypes were evaluated under normal (continues flooding) and drought (irrigation every 12 days) conditions at the experimental farm of the Rice Research and Training Center, Sakha, Kafrelsheikh, Egypt during 2011 and 2012 to study the genetic variability, phenotypic correlation as well as identify the desirable genotypes that could be used as donors in rice breeding program. Combined analysis of variance was performed for data collected on number of panicles plant^-1, 100-grain weight (g), sterility percentage (%), grain yield plant^-1 (g), Harvest index (%) and water use efficiency (WUE) (kg/m³). Highly significant differences were observed among the genotypes for all studied traits. Genotype × Environment mean squares were highly significant for all the examined traits. The genotypes GZ 1368-S-5-4, Morobrekan, GZ 5121-5-2, WAB 878 and Goari were recorded the best performing entries under the drought conditions for grain yield plant^-1 (g) (31.38, 30.98, 29.73, 28.99 and 29.25 g) and some of its related traits and could be used as donors to enhance such traits. Among the studied traits grain yield plant^-1 (g) and harvest index (%) had the highest genotypic and phenotypic variances. WUE recorded the lowest genotypic and phenotypic variances under both conditions. The phenotypic coefficient of variability (PCV%) was higher than genotypic coefficient variability (GCV%) under both normal and drought conditions for the all traits indicating the existence of wide genetic variability in these genotypes and that selection to improve such traits could be practiced effectively in the segregating populations after crossing among them. High estimating values of heritability were observed in all the examined traits under the normal and drought conditions except for harvest index under drought stress condition. Highly significant and positive correlation
coefficient was determined between grain yield plant^-1 and most of the yield attributes under the normal and drought conditions.