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ThesisItem Restricted Induced mutagenesis using physical and chemical mutagens in African marigold (Tagetes erecta L.)(Punjab Agricultural University, Ludhiana, 2020) Anuradha; Parminder SinghThe present investigations entitled “Induced mutagenesis using physical and chemical mutagens in African marigold (Tagetes erecta L.)” were undertaken at Research farm, Department of Floriculture and Landscaping, Punjab Agricultural University, Ludhiana during 2018-2020. In this study, experiments were conducted to standardize dose of physical mutagen (gamma radiations) and chemical mutagen (EMS) for induction of mutations in M1 and M2 generations. Different doses of gamma rays used were 0, 50, 100, 150, 200, 250 and 300 Gy and different concentration of EMS were 0, 0.2%, 0.3%, 0.4%, 0.5% and 0.6% to treat marigold seeds of variety „Punjab Gainda No.1‟. The optimum dose of LD50 for marigold was been worked out as 166.50 Gy for gamma rays and 0.49 % for EMS concentration by probit analysis of survival percentage. The seeds treated with gamma rays resulted in decrease in germination percentage, survival percentage, field survival percentage, plant height, plant spread, number of branches per plant, leaf area, chlorophyll and carotenoid content, number of flowers per plant, flower size, ray floret length and width, fresh weight and dry weight of flower and number of seeds per flower with increase in dose of gamma rays while the lower dose of gamma rays at 50 Gy has stimulating effect on plant height, plant spread, number of branches per plant, number of flowers per plant, flower size, ray floret length, ray floret width, fresh weight of flower, dry weight of flower and number of seeds per flower. The treatment with EMS resulted in decrease in germination percentage, survival percentage, field survival percentage, plant height, plant spread, number of branches, leaf area, chlorophyll and carotenoid content, number of flowers per plant, flower size, ray floret length and width, fresh weight and dry weight of flower and number of seeds with increase in concentration of EMS. Parameters such as leaf abnormalities percentage, floral abnormalities percentage, morphological abnormal plant percentage, days to bud appearance, days to first flower, days to 50% flowering and days to full bloom and flowering duration increased with increase in gamma ray doses and EMS at highest doses in experiment. Visible variations were induced by treatment with both mutagens with respect to change in height, plant stature, variations in leaves from colour to shape of leaves, leaf variegations with EMS, variations in floral colours from yellow-orange to yellow color, flower shape and size of disc and ray florets. One sectorial chimera with different shades from orange to yellow-orange colour in one flower was also observed at 0.5% EMS dose.ThesisItem Restricted Studies on genetic diversity in chrysanthemum (Chrysanthemum morifolium Ramat.) through hybridization, cytological and molecular approaches for commercial traits(Punjab Agricultural University, Ludhiana, 2020) Anu Bala; Madhu BalaThe present investigations entitled “Studies on genetic diversity in chrysanthemum (Chrysanthemum morifolium Ramat.) through hybridization, cytological and molecular approaches for commercial traits” were undertaken at Department of Floriculture and Landscaping, Department of Plant Breeding and Genetics and Fruit Molecular Biotechnology Lab in School of Agricultural Biotechnology, Punjab Agricultural University, Ludhiana, during 2016-19. The study consisted of genetic diversity analysis of diverse genotypes of chrysanthemum through cytological, molecular studies and hybridization for commercial traits. Thirty chrysanthemum genotypes were selected from chrysanthemum germplasm maintained at PAU, Ludhiana for cytological studies. Young flower buds were used for preparation of slides and a range of ploidy level 2n=52-116 recorded among all selected chrysanthemum cultivars. In molecular characterization SSR markers were used to study genetic diversity of thirty chrysanthemum genotypes. Total 17 SSR‟s were selected and among these 15 markers exhibited polymorphism and remaining two were monomorphic. Fifteen polymorphic markers demonstrated relatively high level of polymorphism as out of total 53 alleles produced, 47 were polymorphic showing 92.22 % polymorphism. Genotypes were clustered into two main clusters based on the variability of 15 polymorphic SSR markers. In hybridization twenty-one crosses were made between cultivars belonging to early and main season group. Among twenty-one crosses seed set was recorded in sixteen crosses and germination per cent was observed in fourteen crosses only. Maximum number of seeds per flower head were found in cross Ratlam Selection x Reagan Emperor (11.00), highest seed germination percentage (40.00 %) was recorded in cross between Basanti x Reagan Emperor and seedling vigour found highest (60.00) in cross between Basanti x Reagan Emperor. Hybrids developed from inter crossing of chrysanthemum genotypes were evaluated for various morphological characters and showed variation with respect to flower colour and flower type can be used for different purposes like for pot culture, exhibition purpose and for loose flower production etc. From the effective positive response in terms of various investigations under study, it can be concluded that chromosomal and molecular study helped to estimate genetic diversity which is the most essential pre-requisite as it plays an important role in developing new and novel desired forms through breeding and selection. Polyploidy found could be further helpful for breeding programmes and new cultivars could be developed by addition or deletion of chromosomes in cultivars with known ploidy level. Hybridization helps in development of segregating population having different range of flower colour and height and can be used for different floricultural purposes.
