Kessy, Theodore Thomas2026-02-272026-02-272009https://www.suaire.sua.ac.tz/handle/20.500.14820/7338DissertationPhenotypic and genotypic variation, heritability, correlation and path analyses for 11 agronomic traits and 7 quality traits were conducted to acquire information on their relationships and interdependency for establishing selection indices in rice breeding programs. The study involved 14 F5 rice lines and one check variety, field grown at AR1-KATRIN, during March to August 2007. Phenotypic data were collected for grain yield, yield components and grain quality variables. Twelve hills for each plot were randomly sampled from completely randomized blocks replicated four times. Plant performance revealed high genetic divergence and phenotypic variability in the crop, with the maximum range of variation being for yield components and the minimum for grain quality variables. Genotypic correlations showed that plant biomass (PB), number of panicles per hill (P), maximum number of tillers (TN), panicle weight (PW), percent filled grains (FG) and 1000 grain weight (GW) had stronger positive associations with grain yield while number of grains per panicle (GN) showed the highest positive direct effect on grain yield followed by FG, GW, PB and P. Among the indirect yield contributors, TN had the highest positive effect on yield through PB. Besides, GW, FG, GN, PB exhibited high heritability. Thus selection for these traits would be effective in grain yield improvement. Amylose content (AC), gelatinization temperature (GT) and gel consistency (GO) registered strong positive correlations and covariances among themselves, which indicate high possibilities of being inherited and improved together. They also had high heritabilities ranging from 84-87%. Grain length (GL) showed positive correlation with length: breadth ratio and aroma. Aroma also had positive correlation with GC and poor association with the rest. Although aroma had the highest heritability value, its low genetic gain compounded by being recessive in nature requires that selection for aroma be delayed until later generations.enGrain yieldGrain qualityGrain componentsRice breedingThesis