Selection in the M2 Generation of Soybeans (Glycine Max (L.) Merill) irradiated with Cobalt – 60 Gamma Irradiation in the Guinea Savannah Agroecology of Ghana
Field studies were conducted at the research fields of the University for Development Studies, Ghana from July to November, 2014 and June to October 2015. The studies were aimed at investigating the effect of gamma irradiation on growth and grain yield of soybean. Seeds of soybean variety Jenguma were subjected to gamma irradiation at 150, 200, 250 and 300 Gy from the 60Co source at the Biotechnology and Nuclear Agricultural Research Institute of the Ghana Atomic Energy Commission in Accra, Ghana. The irradiated seeds and some unirradiated control (0 Gy) were planted during the 2014 cropping season in a randomized complete block design with three replications. At harvest, all M1 seeds for respective gamma ray doses were harvested and composited, and advanced to the M2 generation during the cropping season of 2015. In M1, gamma irradiation significantly (P < 0.05) affected seedling emergence. There was significant reduction in survival of seedlings especially from the 150 Gy. Seedling heights of the irradiated species were significantly (P < 0.05) reduced. Number of days to 50% flowering was also significantly (P < 0.05) affected. In M2, more desired traits were found from plants irradiated with the 200 Gy and 250 Gy doses, with only few in the 150 Gy and 300 Gy treated plants. There was a potential for total grain yield improvement. Numbers of pods per plant and seed weight were the key parameters found to influence grain yield. Maturity period was also found to be shorter in the selected plants. The shattering resistance of plants in the 200 Gy and 250 Gy was found to be a potential improvement over the parental variety ‘Jenguma’ which was originally bred for that purpose. Selected plants would be advanced into M3 generation for further studies and results will be published
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