Phenotypic characterization and genetic diversity studies of selected rice (oryza sativa l.) populations based on aroma and cooked kernel elongation
Wambua, Festus Kioko
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Rice (Oryza sativa L.) is the main staple food for more than half of the world’s population. Improving cooking and eating quality of rice is one of the important objectives of many plant breeding programs. Aroma and cooked kernel elongation are two critical parameters that determine the market value, cooking and eating qualities of rice. The objective of this study was to evaluate the phenotypic and genetic diversity of thirteen (13) Oryza sativa L. populations from Kenyan and Tanzanian. Genetic diversity was determined using 8 simple sequence repeats (SSR) markers. Phenotypic diversity was determined based on measurement of seven (7) grain and kernel traits. Diversity data was analyzed using Minitab 17.0 and Power Marker version 3.25 software packages (North Carolina State University).The number of alleles per locus ranged from 2 to 4 alleles with an average of 3.12 across 8 loci. The polymorphic information content (PIC) ranged from 0.2920 (RM 282) to 0.6409 (RM 339) in all loci with an average of 0.4821. Pair-wise genetic dissimilarity coefficients ranged from 0.1125 to 0.9003 with an average of 0.5312. Maximum genetic similarity was observed between Kilombero and Supa, BS 370 and BS 217. Minimum genetic similarity was observed between Kahogo and BS 217. Cluster analysis was used to group varieties by constructing dendrograms based on SSR data and morphological characterization of grains. The dendrogram based on SSR data formed two distinct clusters of the 13 rice varieties. RM 339 and RM 241 were the most informative markers and could be used for differentiating rice varieties from diverse geographical origins. The results obtained from this study demonstrated that phenotypic trait measurement and use of trait specific SSR markers can be relied upon in diversity studies among diverse and closely related genotypes.RM 339 and RM 241 markers are recommended for use in diversity studies and in quality assurance for grading of rice varieties. Further analysis should be carried out using a larger number of samples and markers to come up with a more conclusive report on the discriminating power of microsatellite markers based on rice grain quality traits.