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Author: Divya × End date: 2019 × Start date: 2016 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Application of triple test cross method, selection procedures and SSR markers in bread wheat (Triticum aestivum L.em. Thell)
    (CCSHAU, 2016) Divya; Panwar, Ishwar Singh
    The objectives of present investigation were to detect and estimate additive and dominance components of genetic variation and to study the genotype x environmental interactions for genetic components, to compare variability generated by different selection procedures i.e. conventional pedigree selection, selected spike bulk breeding, multiple seed descent (one spikelet-one plant) and selection on yield per sein early segregating generations and to analyze genetic diversity among wheat genotypes using Simple Sequence Repeat markers. The results of the analysis of variance of the triple test cross families indicated both the additive and non-additive components were involved in the inheritance of most of the traits with preponderance of the former. Additive genetic component and ‘j’ and ‘l’ type of epistasis were relatively more sensitive to environmental change than the dominance gene effects and ‘i’ type epistasis. Early generation intermatings have been suggested for exploiting both types of gene effects simultaneously in the present material. The mean values of F 4 pedigree selection generated through single plant selection were, in general, higher than those of other populations in both the crosses. Pedigree selection and selected spike bulk, in order, were found better as compared to other selection procedure i.e. multiple seed descent (single spikelet selection) and selection on yield per se. Hence, these two procedures appeared to be equally effective in handling segregating generations of wheat crosses. Genetic diversity analysis using SSR markers detects a total of 181 alleles. The number of alleles per locus ranged from 1-5 with an average of 2.6 alleles per locus. The overall size of PCR products amplified ranged from 100-475 bp. NTSYS-PC UPGMA cluster analysis led to grouping of 44 genotypes in such way that genotypes within each cluster had higher similarity than between clusters. The dengrogram divided broadly into two groups at the similarity coefficient of 0.620. The group I was very large and include 43 genotypes while group II includes only one genotype (Tobari) which indicates that this genotype was highly diverged with respect to other genotypes. Similarity coefficients between all genotypes ranged between 0.62 to 0.81 and averaged 0.71. Similarity coefficient showed the most closely related wheat genotypes were WH 1182 and WH 1124 and highest similarity index 0.81 while most diverse genotypes were Tobari and HD 2967 with low similarity index of 0.62.