Application of triple test cross method, selection procedures and SSR markers in bread wheat (Triticum aestivum L.em. Thell)
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Date
2016
Authors
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Publisher
CCSHAU
Abstract
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.
Description
Keywords
Wheats, Planting, Genetics, Yields, Selection, Genotypes, Grain, Gene interaction, Environment, Crossing over