Genetic architecture of yield and some quality traits in bread wheat (Triticum aestivum L.)
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Date
2018-09
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Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu, Jammu
Abstract
The present study entitled "Genetic architecture of yield and some quality traits in bread wheat (Triticum aestivum L.)" was carried out during Rabi 2014-15 and 2015-16 at the Research Farm, Division of Plant Breeding and Genetics, SKUAST-Jammu, Chatha and off-season at Regional Research Station of Indian Institute of Wheat and Barley in Dalang Maidan (Lahaul & Spiti), Himachal Pradesh. The experimental material of the present study comprised of twelve true breeding lines of bread wheat which were grown in randomized block design with three replications. Of these, eight lines were deliberately chosen for half diallel mating designs. Out of twelve lines involved, ten lines were used as female parents and two argonomically superior and genetically diverse varieties, namely, PBW343 and RSP561, and their F1 as male testers for set-1 and Raj3077 and PBW175, and their F1 as male testers for set-2 (L1, L2 and L3 respectively) to develop the experimental material for triple test cross mating design. In half diallel experiment analysis of variance revealed significant differences among genotypes for all the traits in both generations except days to maturity, plant height, number of effective tillers per plant, spike density in F1 generation and number of effective tillers per plant, 1000-grain weight in F2 generation indicating sufficient variability present in the experimental material. Mean sum of squares due to GCA and SCA were found to be highly significant for all the traits studied in both generations except number of effective tillers per plant in F2 generation for GCA. The variance for SCA were greater than variance for GCA for all the traits excepts for spike density, number of grains per spike, 1000-grain weight, grain yield per plant, protein content and gluten content in F1 generation, and in F2 generation for flag leaf area, plant height, spike length, number of spikelets per spike, spike density, 1000-grain weight and gluten content which indicated that non-additive type of gene effects were more pronounced than those of additive ones. Four parents viz., RSP561 and DPW621-50 in F1 generation and WH1105 and WH1080 in F2 generation showed significant GCA effects for grain yield per plant. In F1 generation three crosses with both parent as poor combiners; five crosses with one parent as good combiner and one cross with both parent as good combiners and in F2 generation six crosses with both parent as poor combiners; four crosses with one parent as good combiner and one cross with both parent as good combiners were found to be desirable crosses for grain yield per plant and biochemical traits. Significant and positive heterosis for mid and better parents were observed in HD2967 × WH1080, PBW343 × RSP561, Raj3077 × RSP561 and RSP561 × DPW621-50 for grain yield per plant and biochemical traits. According to Hayman's approach, additive genotypic variance (D) was significant for all the traits except number of effective tillers per plant, number of grains per plant, grain yield per plant and biological yield per plant in both generations and number of spikelets per spike in F2 generation. Dominance component (H1 and H2) was also significant for all the traits in both generations. Average degree of dominance in most of the cases confirmed over dominance in both F1 and F2 generations for all traits studied. Wr-Vr graphs showed over dominance for all the traits studied in both F1 and F2 generations.
In simplified triple test cross experiment, all the traits in both sets showed significant total epistasis, i type epistasis in set-1 was found significant for all the traits except for flag leaf area, number of effective tillers per plant, spike length, number of spikelets per spike, spike density and number of grains per spike, whereas in case of set-2 i type of epistasis was non-significant for all the traits except days to 50 percent flowering, flag leaf area, days to maturity, plant height and number of effective tillers per plant, j+1 type of epistasis, were highly significant for all traits in both the sets except biological yield per plant in set-1. The analysis of variance of mean squares for sums (L1i + L2i) and differences (L1i - L2i) in both sets were significant revealing the importance of both additive and non-additive properties of genes.
In the present study, half diallel was found superior since it provides more genetic information as compare to simplified triple test cross for economic and biochemical traits. However, triple test cross appears to be useful in deriving genetic information about the presence of epistasis which is a critical assumption in diallel analysis.
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