Abstract:

The aim of this study was to provide the reference for the radiation breeding of kiwifruit. After treated with 60Co-γ ray, buds from different fruit spurs of two Actinidia varieties were top grafted onto the heavily pruned mature vines with 50-100 grafted buds per adult stock plant. The favorable variants were selected and propagated for several successive years, and the characteristics of new developed strains were investigated. From the progeny vines produced from 25GY-radiated grafted buds, two new strains with distinctive characteristics were finally developed: ‘Heping radiation No.1’ and ‘Hongyang large fruit’. Compared with the control varieties, the new strains exhibited the same phenophase, while the morphological characters showed some differences. The yielding ability of ‘Hongyang large fruit’ had been improved. As for fruit quality, the content of total sugar and vitamin C of two new strains increased significantly in comparison with control varieties. Furthermore, the content of soluble protein of ‘Hongyang large fruit’ was greater than that of its control. The suitable dosage of 60Co-γ ray radiation breeding with kiwifruit buds was between 25 and 50 GY. The multiple top grafting techniques effectively solved the problem that a large population with numerous individuals is required to screening the very few favorable mutations. It was an effective novel way for kiwifruit breeding to combine 60Co-γ ray radiation treatment of kiwifruit buds with multiple top grafting on adult stock plants.