Phenotypic Characterization And Genetic Diversity Studies Of Selected Rice (Oryza Sativa L.) Populations Based On Aroma And Cooked Kernel Elongation

 ABSTRACT

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.