RAJENDRA PRASAD, SNAFLATH, T V2023-01-052023-01-052022-12-29Th-13264https://krishikosh.egranth.ac.in/handle/1/5810191250Sixty diverse genotypes with different seed coat colour and seed size was evaluated for seed longevity under natural ageing for 20 months and accelerated ageing as per International Seed Testing Association (ISTA) guidelines over two season using fresh seeds. Seed germination was recorded at bimonthly interval after storage in natural ageing and another set after accelerated ageing. The correlation between accelerated and bimonthly natural ageing was highly significant. Two black seed coat colour genotypes, Acc No.369 and Acc No.39 consistently showed higher longevity over the ageing treatment and serve as a source of higher seed longevity in soybean. A panel of 96 genotypes was combined for association mapping and the genetic diversity as well as population structure was studied using SSR, Genotyping-By-Sequencing (GBS)-SNP and agro-morphological traits. Bayesian-model based population STRUCTURE, UPGMA and principal component analysis approaches using SSR, SNP and agro-morphological traits exhibited a complementary pattern of population structure. The genotypes with higher seed longevity and small seed size formed a single cluster. Higher coefficient of variability of seven productivity and nine seed longevity related traits confirmed the diversity in assembled population and its suitability for QTL mapping. Genome-wide association mapping using 29,955 GBS-SNP markers and sixteen traits produced 30 marker trait associations. One co-localized SNP (SNW_024464723.1_95172) was identified for seed longevity traits viz., seed germination, seedling vigour index-II and per cent reduction in vigour index-II. The biparental linkage mapping population for seed longevity was also developed by crossing JS93-05 and Local black soybean using Wet cotton and Kolot method with wet cotton method producing higher success rate. High genetic variability was observed among 352 F2 plants. The GBS-SNP resources, association mapping panel and F2 population developed in this study serve as a valuable resource for soybean crop improvement programme.EnglishThesis