CHARACTERIZATION OF PIGMENTED RICE GERMPLASMS BASED ON MORPHO-NUTRITIONAL TRAITS, ANTIOXIDANT PROPERTIES AND MOLECULAR MARKERS

Abstract

The experiment conducted during the Kharif season from April 2022 to November 2022 aimed to analyze the morpho-physiological and nutritional traits, genetic parameters, DNA fingerprinting, and molecular genetic diversity of pigmented rice genotypes. The analysis included ten (10) yield and yield-contributing characters, five (5) nutritional characters, and 14 SSR markers. The experiment revealed significant differences among the genotypes for all traits, showing a good opportunity for selecting better parental types to improve grain yield. The mean performance of different yield and yield contributing characters showed wide variations, with traits like plant height (114.43±2.74) cm, productive tiller per plant (28.85±1.11), unproductive tiller per plant (2.82±0.25), and yield per plant (18.82±1.10) g exhibiting notable ranges. Genetic parameters such as genotypic variance, phenotypic variance, heritability, genetic advance, and genetic advance as a percent of the mean were estimated. The highest genotypic and phenotypic variances were recorded with straw weight (13985.59 and 14158.47), DPPH (4216.64 and 4470.27), days to 50% flowering (1367.09 and 1367.56), iron content (938.47 and 947.76), plant height (373.12 and 395.66), respectively. The low values of phenotypic and genotypic variances were recorded with the character unproductive tiller per plant (1.20 and 1.02), spike per panicle (3.11 and 2.82), thousand seed weight (18.21 and 17.73), respectively. the phenotypic coefficient of variances (PCV) ranged from 17.38% for the plant height to 70.99% for the total phenolic content. The genotypic coefficient of variances (GCV) ranged from 16.88% for the plant height to 70.31% for the total phenolic content. The highest PCV and GCV were observed for the total phenolic content (70.99 and 70.31). The heritability estimation varied from 82.28% to 99.99% for total flavonoid content (TFC) and days to 50% flowering respectively. Furthermore, cluster analysis grouped the genotypes into three clusters based on their traits. Principal component analysis (PCA) identified the minimum number of components explaining the maximum variability principal component 1 (PC1) has an eigenvalue of about 5.77 that captures about 38.5% variance, then the eigenvalue falls steadily in component 4 has an eigenvalue of about 0.99 that captures about 6.6% variance, and the biplot analysis revealed correlations between traits and genotypes. The trait productive tiller per plant, total tillers per plant and panicle length denotes positive PC1 score and negative PC2 score and were highly correlated with each other. Here, the genotypes G21 (BRRI dhan 82), G23 (BRRI dhan 48), G33 (Tepiboro 2), G12 (Nara Bet), G28 (BRRI dhan 29) favored these traits. Again, DPPH content, total flavonoid content and thousand seed weight showed positive loading in PC2 but negative score in PC1. The DNA fingerprinting based on SSR markers identified 57 alleles, and the population structure analysis classified the genotypes into four sub-populations, each with distinct characteristics. The analysis of molecular variance (AMOVA) indicated a higher level of genetic variation (90%) within populations than (10%) among them. The study provides comprehensive insights into the variability, heritability, and genetic diversity of pigmented rice genotypes, offering valuable information for future breeding programs and genetic improvement. Overall, the experiment yielded crucial findings on the diversity, genetic parameters, and population structure of pigmented rice genotypes, such as Orabet aus, Malikhori aus and Narabet aus offering significant implications for breeding and conservation strategies in rice cultivation.