RADIOBIOLOGICAL EFFECTS OF GAMMA IRRADIATION ON WINTER SQUASH (CUCURBITA MAXIMA DUCH.) AND PUMPKIN (CUCURBITA MOSCHATA DUCH.) LINES IN M0 AND M1 GENERATIONS

摘要

Mutation breeding is one of the favorable techniques to the production of new cultivars and lines. But the determination of mutagen type and their appropriate doses the most important points in mutagenesis due to lethality in living organism. In the present study, the winter squash and pumpkin seeds were irradiated with a Co60 source at five gamma ray doses (50, 100, 200, 300 and 400 Gy). Radiobiological effects of the gamma rays were investigated in root tip cells of germinated seeds in the M0 (irradiated seeds) and M1 generations of winter squash and pumpkin lines via mitotic index (MI), mitotic abnormalities (MA) (total abnormal cell, abnormality percentage, and chromosomal aberrations). Seeds irradiated with doses of up to 200 Gy exhibited similar MI and MA as nonirradiated control seeds. While cell division sharply interrupted and reduced, MA gradually increased at 300 Gy and 400 Gy gamma ray doses. M0 showed the greater decrease in MI and increase in MA than M1 generation.