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M. Sc. Dissertations

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20112
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Subject: Genetics × End date: 2011 × Start date: 2011 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Genetic diversity and correlation analysis for morphological traits and grain yield in advanced lines of bread wheat
    (CCSHAU, 2011) Sharma, Preeti; Yadava, R.K
    The study entitled “Genetic diversity and correlation analysis for morphological traits and grain yield in advanced lines of bread wheat” was conducted during rabi 2009 at CCSHAU, Hisar. The advanced homozygous lines (170 nos.) were undertaken for genetic divergence and for estimate of mutual correlations vis-a-vis path analysis for grain yield with 10 morphological traits namely days to 50 % heading, plant height (cm), peduncle length (cm), spike length (cm), spikelets per spike, number of effective tillers per plant, spike weight (g), weight of grains per spike (g), number of grains per spike, hundred grain weight (g). Coefficient of variation being in the range of 1.40- 8.34 indicated adequacy of material and the traits studied for further estimation of genetic variability parameters. Heritability (broad sense) estimates were quite high for grain yield per plant followed by hundred grain weight and number of effective tillers per plant. Improvement can be realized to an extent ranging from 66 to 30 per cent for grain yield per plant, tillers per plant, hundred grain weight, and grain weight per spike. Highly significant and positive association was observed between grain weight per spike and spike weight. The high direct effects in positive direction for the dependent variable i.e grain yield per plant was recorded for number of effective tillers per plant followed by number of grains per spike, and hundred grain weight. In general, the indirect effects of the characters towards grain yield per plant were low, but the main contributers are tillers per plant, number of grains per spike and hundred grain weight. Hierarchical Euclidean cluster analysis of 170 genotypes into 9 clusters with variable number of advanced lines which indicated the presence of considerable amount of genetic diversity in the material. The average intra- cluster distance between the advanced lines was recorded maximum for cluster IV thereby indicated the presence of more diversity among the genotypes included among these cluster. The inter-cluster distance has been maximum between clusters II vs. VII followed by cluster IV vs. VII and VI vs. VII and was least for cluster I vs. II. The maximum per cent contribution towards the total genetic divergence was indicated for grain weight per spike followed by grain yield per plant, hundred grain weight and plant height. Based on cluster mean, the genotypes that may be promising for the improvement programme in bread wheat are identified as RIL- 91from cluster IV for plant height and number of spikelets per spike. RIL- 31 from cluster VII was found better for number of grains per spike and grain yield per plant. RIL- 45 from cluster VIII could be explored for maximum hundred grain weight and minimum days to 50 per cent heading as well. It is suggested that grain yield can be improved through direct selection for effective tillers per plant, number of grains per spike and hundred grain weight.
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    ThesisItemOpen Access
    Genotypic variation for seed size and related traits in wheat (Triticum aestivum L.)
    (CCSHAU, 2011) Aggarwal, Madhu; Dahiya, Gajraj Singh
    The present investigation entitled “Genotypic variation for seed size and related traits in wheat (Triticum aestivum L.)” was conducted during rabi 2009-2010 under normal and late sown environments at CCSHAU, Hisar. Ten genotypes (SG22, Raj3765, PBW550, LOK1, K68, C306, WH283, WH542, HJP62 and HD2009) representing a wide range of spectrum of variability for their grain size (bold, intermediate and small) were used for the estimation of grain filling parameters, the main causal components of grain size. Accumulated growing degree days (GDD) from anthesis was used as the time scale during the grain development period. Field observations were recorded from five competitive plants for days to 50% heading, days to anthesis, days to maturity, number of grains per spike, spike length (cm) and 1000-grain weight (g). Grain development rate (GDR) and grain development period (GDP) were calculated for each genotype replication wise fitted by non linear regression to a logistic curve. Significant genotypic differences were present for all the characters under normal and late sown environments. The relative ranking of the genotypes for grain development period differed in two environments. This implied that GDP was more sensitive to the environment. On the other hand GDR was more stable trait and least affected by the environment and hence more genetically controlled. Highly significant and positive association was observed between GDR and 1000-grain weight under both the conditions. This association was stable over the environment and could account for 50% variability for 1000-grain weight. GDR exhibited highly significant negative association with GDP under normal sown condition whereas direction of association was also negative but non-significant under late sown condition. The characters such as 1000-grain weight, number of grain per spike, spike length and days to maturity had higher magnitude of genetic variance as compared to environmental variance and this was also reflected by higher magnitude of broad sense heritability for these traits under both conditions. The expected genetic advance (% of mean) was highest for GDR followed by 1000-grain weight, number of grains per spike and spike length under both environments ranging (32 – 64%) whereas for GDP a medium response ranging (17 – 22%) was expected. The results indicated that the grain size may be genetically manipulated by improving the GDR in the wheat population.