Genetic Divergence of Lowland Rice (Oryza sativa L.) Genotypes in Uganda

Forty-eight lowland rice genotypes with two checks were evaluated for agronomic performance, genetic variability, heritability, and genetic advance for yield and yield contributing traits. Genotypes SR33859-HB3324-133 (45.7 qha-1), SR33859-HB3324-93 (40.2 qha-1) were the high yielding genotypes above the better check. The analysis of variance showed significant differences for all measured traits and indicating the presence of high genetic variability among genotypes. A highly significant (P≤0.001) correlations were observed between flag leaf length and plant height (rp= 0.76 and rg=0.84), panicle length and plant height (rp= 0.77, rg= 0.90), and panicle length and flag leaf length (rp= 0.75 and rg= 0.89). The estimates of GCV were lower than the respective PCV for all traits, indicating the influence of environmental factors on the expression of the traits. Characters like grain yield (94 % and 90.9), flag leaf length (97 % and 71.6), number of effective tillers per hill (91 % and 67.2) and plant height (99.0 % and 50.7) showed high heritability coupled with moderate genetic advance as percent of the mean, which suggesting that these traits are controlled by the additive type of gene action and selection could be possible for the improvement of these characters. Moderate heritability estimates with low genetic advance as percent of the mean were recorded for flag leaf width and number of days to maturity indicated the presence of non-additive gene effects, and selection for these traits would be poor. As a result, the variability that exists in the germplasm provides an opportunity to use these genotypes in the genetic improvement program.