Parminder SinghAnuradha2021-01-122021-01-122020Anuradha (2020). Induced mutagenesis using physical and chemical mutagens in African marigold (Tagetes erecta L.) (Unpublished Ph.D. Dissertation). Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810159906The 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.EnglishThesis