MORPHOLOGICAL AND MOLECULAR CHARACTERIZATION OF GENOTYPES DERIVED FROM WILD CROSSES OF RICE (Oryza sativa L.)
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Date
2023-12-04
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Acharya N G Ranga Agricultural University
Abstract
The current investigation entitled “Morphological and molecular characterization of genotypes derived from wild crosses of rice (Oryza sativa L.).” was carried out during kharif, 2021 at Agricultural College Farm, Bapatla, Bapatla district of Acharya N. G. Ranga Agricultural University (ANGRAU) with 49 diverse rice genotypes derived from crosses between elite rice genotypes and IRGC lines. This experiment was carried out with the key objective of identifying the genotypes with high yield potential, in addition to draw the precise information on nature and extent of variability, heritability and genetic advance as per cent mean for morphological, yield components and grain quality traits. Character association between the morphological and yield related traits and grain yield per plant to aid in the improvement of rice genotypes and molecular characterization of these genotypes using trait specific SSR markers.
The analysis of variance for morphological, yield components and grain quality traits unveiled significant differences among the genotypes for all the traits under investigation indicating that presence of ample variation among the genotypes studied. The estimates of phenotypic coefficient of variation for all the characters under study were of higher magnitude when compared with the estimates of genotypic coefficient of variation and the variation is less between these two estimates for most of the traits denoting negligible amount of environmental influence on the expression of these traits.
The overall results of genetic parameters among morphological, yield related and grain quality traits reported high estimates of GCV, PCV, heritability and genetic advance as per cent of mean for grain yield per plant indicating the prevalence of additive gene action in the inheritance of this trait. Hence, simple selection will be highly rewarding for improving this character. However, low GCV and PCV in addition to low heritability and genetic advance as per cent of mean were noticed for ear bearing tillers indicating the role of non-additive gene action in the inheritance of this trait. Thus, hybridization, mutation breeding followed by selection and progeny testing method is advocated for improvement of this trait.
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The perusal of results on character association between morphological and yield component traits and grain yield unfolded that positive and significant relationship of grain yield per plant was observed with days to 50% flowering, plant height, number of primary branches per panicle, ear bearing tillers per plant, number of fertile grains per panicle and test weight indicating that grain yield will be improved simultaneously along with these characters. Hence, ample scope should be given to these traits while making selection for improvement of grain yield per plant. In contrast, grain yield manifested negative correlation with kernel length and L/B ratio suggesting that genotypes with slender grain type recorded less grain yield per plant. Number of ear bearing tillers per plant manifested significantly negative relationship with panicle length, kernel length, L/B ratio and test weight. Number of primary branches per panicle exhibited negative and significant association with test weight suggesting that the genotypes with more number of primary branches had slender grains with less test weight. Likewise kernel breadth manifested negative relationship with L/B ratio indicating the need for balanced selection while simultaneously improving these traits.
Molecular characterization of 49 rice genotypes with 27 trait specific SSR markers linked to yield-related characters revealed that markers RM251 and RM263 exhibited higher PIC value of 0.62 followed by RM324 (0.61) and RM404 (0.610) in addition to most effective alleles and the higher Shannon's information and Nei's genetic diversity indices. Therefore, these markers can be regarded as more efficient and were capable of effectively differentiating the genotypes for the traits under study. The results of cluster analysis by using UPGMA method revealed that all the 49 genotypes were grouped into two major clusters. Cluster I comprising of 45 genotypes was further divided into two sub-clusters (IA and IB). Sub-cluster IA comprised of 44 genotypes, sub-cluster IB comprised only one genotype. Sub-cluster IA was further sub divided into two sub-sub cluster IA-1 with 40 and IA-2 with 4 genotypes and cluster II comprised only 4 genotypes.
Furthermore, out of 27 SSR markers used in the present study that were found to be associated with yield related traits, 12 markers manifested polymorphism. The results of both genotyping and phenotyping results revealed that the markers RM154, RM251, RM204 and RM324 showed positive association with the respective phenotypic traits under consideration in the current study. The above markers were capable of distinguishing genotypes for the traits and thus, these markers may be utilized as gene linked markers in future marker assisted rice breeding programs. In this context, genotypes BPT 2848, BPT 2955 and BPT 3137 possessed the positive alleles for these four markers. Hence, these genotypes offered promise in their use in the genetic improvement of rice cultivars for grain yield and quality.