Effects of irradiation and cold storage on rooting and growth of chrysanthemum cuttings

This study was carried out to investigate the combined effect of cold storage with irradiation on rooting of chrysanthemum cuttings. Each cutting had three real leaves and was 6 cm in length. Groups of the cuttings were irradiated with 0 to 70 Gy of gamma-ray after cold storage, while another groups were irradiated with the same doses and then stored at 4 .deg. C for four weeks. Root and shoot growth was observed at 15 and 20 days after planting of the cuttings in a plug tray. Accelerated root formation was observed in 30 Gy irradiated group, and root growth was also enhanced in 20 and 30 Gy irradiated groups 20 days after planting. In case of irradiation combined with pre-treatment of cold storage, survival rate of cuttings was the highest (80%) in 30 Gy irradiated group. The groups treated with cold storage after irradiation were generally better in root formation, among which 50 Gy irradiated group showed the highest rate of root growth