Abstract:

Aiming at the key problem of asynchronous flowering in the hybrid breeding of begonia species, to clarify the variation law of pollen viability and the optimal storage protocol for Begonia handelii and Begonia masoniana, the in vitro germination method was adopted to systematically investigate the effects of flowering days (1-13 d for B. handelii and 1-5 d for B. masoniana), drying methods(oven drying at 25-26℃ for 3-4.5 h and natural air drying for 24 h), and storage conditions (room temperature of 22-28℃, 4℃, and -20℃) on pollen viability. The results showed that pollen viability was highest on the third day after flowering for both begonias, reaching 87.83% for B. handelii and 86.14% for B. masoniana. Oven drying was superior to natural drying for both begonias. Pollen viability reached over 81.49% after one day of storage at room temperature and over 62.59% after 90 days of storage at 4℃. Pollen viability reached over 90.82% for both begonias after 30-180 days of storage at -20℃, and remained above 86.03% after 360 days of storage. Therefore, the optimal pollen collection period for B. handelii and B. masoniana is on the 3rd day after flowering. It is recommended that the pollen be oven-dried at 25-26℃ prior to cryopreservation at -20℃. The results of this study provide technical support for pollen utilization in the hybrid breeding of begonia species. Subsequent research can be carried out on ultra-low temperature storage technology, which will lay a foundation for the long-term preservation of germplasm resources.

Key words: Begonia handelii, Begonia masoniana, pollen viability, drying methods, storage