Brar, K.S.Narinderpal Singh2019-09-132019-09-132019http://krishikosh.egranth.ac.in/handle/1/5810127608In the present investigation, a set of 35 confectionery groundnut (Arachis hypogaea L.) genotypes was irradiated at 200, 300, 400 and 500 Gy gamma irradiations for standardizing the optimum dose that could be used to irradiate the same set of genotypes for screening for collar rot resistance and obtaining variation in morpho-agronomic characteristics, yield and biochemical components desirable for use of groundnut in food and confections. Optimum dose was obtained on the basis of 50 per cent growth reduction (GR50) in vitro of seedlings raised from irradiated seed by subjecting both, seedling vigour index I and II to probit analysis. Effect of gamma irradiation on growth parameters (germination percentage, shoot and root length, total seedling length, seedling dry weight) was calculated to obtain values for both vigour indices. All these growth parameters were found negatively correlated with gamma irradiation. Optimum dose range inferred was 244-520 Gy. Based on this, same set of genotypes was irradiated at 200, 300, 400 and 500 Gy gamma irradiation to raise M1 generation in vivo to obtain M2 population. Per cent disease incidence (PDI) of all the genotypes increased with increase in gamma radiation in M2 generation. Resistance reaction for any genotype at any gamma ray dose was not observed. Morpho-agronomic characteristics (per cent emergence, plant height, number of primary branches and leaves per plant, leaflet length and width) and maturity period generally decreased and increased respectively, with increase in gamma irradiation in both M1 and M2 generations. This reduction was more pronounced in M1 compared to M2 generation mainly for per cent emergence, plant height and days to maturity indicating restoration of damaged DNA in M2 generation that occurred during M1 generation, while other parameters remained unaffected or showed variation due to environmental heterogeneity. Though, effect of gamma irradiation on yield components (pod number, yield and sound mature kernels per plant, 100 seed weight and shelling percentage) observed a negative shift, some genotypes at different gamma ray doses showed increase in values compared to the control, thus providing desirable variation for yield improvement. Among biochemical components, only sugar content observed a significant reduction, while protein and oil content were not significantly affected by gamma irradiation.ennullThesis