Biological effects of ⁶⁰Co-γ irradiation on yanshanzaofeng graft

To identify the irradiation effects of ⁶⁰Co-γ ray on flower and leaf characters, fruit qualities of chestnut and suitable dose, the main cultivated varieties of chestnut Yanshanzaofeng grafts in local varieties were tested. The grafts were treated with seven different levels of ⁶⁰Co-γ dose at 0, 15, 20, 25, 30, 35, 40 Gy. Survival ratio, characteristic variation of leaves and flowers, photosynthesis parameters of chestnut leaves, fruit single-grain weight and fruit qualities were examined to study the biological effects on chestnut grafts with ⁶⁰Co-γ irradiation. The result showed that grafting survival rate decreased as the irradiation dose increased, and the survival rate dropped to 0 when the irradiation dose was more than 30 Gy. According to the fitting equation of irradiation dose and survival rate, the LD₅₀ dose of chestnut graft was 20.26 Gy, irradiation by ⁶⁰Co-γ led the male flowers increased, the leaf enlarged, leaf curled, leaf photosynthetic rate increased, fruit single-grain weight increased, and fat, soluble sugar, protein and amylose content which affecting the fruit quality increased. The study provided a certain theory basis to cultivate the high photosynthetic efficiency and high quality chestnut varieties by irradiation mutation breeding. (authors)