GENETIC AND MOLECULAR CHARACTERIZATION OF LANDRACES IN RICE (Oryza sativa L.)
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Date
2023-12-07
Authors
YECHURI PRAVALLIKA
Journal Title
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Publisher
Acharya N G Ranga Agricultural University
Abstract
The present investigation “Genetic and Molecular Characterization of Landraces in Rice (Oryza sativa L.)” was carried out during Kharif, 2021 at Regional Agricultural Research Station, Maruteru, Andhra Pradesh consisting of 100 landraces along with one resistant, one susceptible and two high yielding checks of rice to know the extent of variability and diversity among the landraces. Heritability and genetic advance for yield and its attributing traits were assessed along with the association among yield, yield components with their direct and indirect effects on grain yield/plant. Further the genotypes were screened for BPH resistance under field and laboratory conditions and characterised using markers linked to BPH resistant genes.
The analysis of variance using augmented design revealed significant differences among 100 landraces for all the characters under study indicating the presence of sufficient genetic variation in the experimental material for exploitation.
Moderate PCV, GCV and high heritability coupled with high GAM were observed for plant height, panicle length, test weight and grain yield/plant indicating the presence of additive and non-additive gene actions. The characters governed by additive gene action can be fixable in the early generation itself. Whereas, for those traits which are governed by non-additive gene action, the selection may be postponed to later generations.
Results on correlation and path analysis between yield and its attributing traits revealed significant and positive association of grain yield/plant with number of ear bearing tillers/m2, panicle length and test weight in addition with positive direct effect on grain yield indicating simultaneous improvement of grain yield with the improvement of these traits.
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Principal component analysis revealed that, first three of eight principal components recorded eigen value greater than one having cumulative frequency of 73.05%. The landraces LRP 276, LRP 458, Sri Dhruthi, LRP 118, LRP 257, LRP 373, LRP 300, LRP 248, LRP 350, LRP 453, LRP 116 and Chandra were found to be highly divergent, and can be exploited in the hybridization programmes.
The results of phenotypic screening for BPH resistance revealed that, six landraces viz., LRP 58, LRP 60, LRP 84, LRP 177, LRP 220 and LRP 226 showed resistance in both the screening methods indicating their utilization in the breeding programmes of rice.
The molecular diversity studies revealed that 33 of 50 markers were polymorphic, distributed across 12 chromosomes. Among 33 polymorphic markers, the marker RM260 exhibited the highest PIC value (0.82), maximum number of effective alleles, high Shannon’s information index and high genetic diversity index. The marker, RM8213, produced maximum of five alleles whereas, the marker, RM5953, showed high major allele frequency value of 0.99. The results of cluster analysis by using UPGMA method revealed that all the 100 landraces along with four checks were grouped into three major clusters. Cluster I was divided into 2 sub clusters consisting of 37 and 31 genotypes. Cluster II was divided into 2 sub clusters consisting of 15 and 9 genotypes. Cluster Ⅲ was divided into 2 sub clusters consisting of 10 and 2 genotypes respectively.
The landraces LRP 84, 177 and 220, exhibited phenotypic resistance in both field and green house screening and are associated with 2 resistant genes (Bph4 and Bph12) which confer BPH resistance. The landraces viz., LRP 58, LRP 177, LRP 220 and LRP 226 are high yielding genotypes on par with yield check, Sri Dhruthi and exhibited BPH resistance in both the methods. These landraces can be used as donors in the hybridization program to develop new rice cultivars with high yielding ability coupled with BPH tolerance.