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20141
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Subject: Plant Breeding and Genetics × Author: Akhatar, Javed × Type: Thesis ×
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    ThesisItemOpen Access
    Genetic Diversity and Association Studies for traits Related to Water Stress Tolerance in a Structured Brassica Juncea Population
    (PAU, 2014) Akhatar, Javed; Banga, S.S.
    A core subset of genetically fixed lines (48) was selected through stratified sampling to represent the allelic variations within Brassica juncea gene pool. The molecular characterization by 158 nuclear and nine chloroplast SSR markers revealed distinct germplasm patterns. There were significant interactions between chlorotype and seed/biological yields. Test genotypes were also evaluated for twenty four morpho-physiological traits over two years under normal and restricted moisture regimes for association studies. Highly significant marker-trait associations (MTA‟s) were identified by General Linear Model [GLM-PC (Principal Component)] Mixed Linear Model [MLM-PC+K (Kinship)]. MTA‟s include days to maturity, grain yield, number of secondary branches, number of seeds per pod, thousand seed weight, average root diameter and root length. Single marker, SB1822-1, localized at 17.5cM on chromosome 13 was repeatedly detected for seed size and grain yield. Marker, SB3872-3 revealed significant effect under normal moisture on seed size during the year one. Among the favorable double alleles, SB1822-1 showed positive phenotypic effect for thousand seed weight and grain yield. Of the four double alleles, cnu316-3 had maximum positive phenotypic effects on grain yield. Maturity QTLs (Quantitative Trait Loci) detected on J6 (A genome) have been repeatedly detected in past studies with diverse in B. napus. Novel QTLs were identified for photosynthetic active radiation interception (cnu031-1 and SB1728-3) and drought tolerance index (NI3-G07-1 and SB1935A-1) and canopy air temperature difference. The loci identified by us need to be verified and utilized for breeding tolerant cultivars to improve crop performance under variable moisture conditions.