Abstract: [Objective] To determine the possibility to produce triploids by pollen chromosome doubling induced with high temperature exposure, and to produce new triploid germplasm to breed new varieties of Populus canescens with better resistance and serve for ecological environment protection.[Method] Based on the observation of male meiosis, pollen chromosome doubling induced by high temperature exposure to produce hybrid triploid was conducted using aceto-carmine staining and chromosome doubling technique in P. canescens.[Result] The results indicated that it took 5-6 days for pollen mother cells (PMCs) to complete meisois. Compared to other Populus species, no significant differences in process of meiosis was observed in P. canescens. However, significant asynchronism of male meiotic progress of PMCs in the same bud was observed. The top of PMCs developed faster than the basal of PMCs in the same male bud. However, the middle PMCs was the slowest ones. The optimum treatment combination to induce pollen chromosome doubling was to use 38 or 41℃ high temperature to treat male buds for 6 hours when the meiotic stages of PMCs were from diplotene to diakinesis. The highest frequency of 2n pollen is 58.03%. 911 seedlings were obtained by crossing the treatment combination with higher frequency of 2n pollen with female gametes of P. alba. Among all the progenies, 42 triploids were detected, and the highest triploid production rate was 10.71%. Correlation analysis between the frequency of 2n pollen and triploid production rate was carried out. Non-significant positive correlation was observed between the frequency of 2n pollen and triploid production rate (r=0.599, P=0.116), suggesting that increasing the frequency of 2n pollen could help increase the triploid production rate.[Conclusion] Though significant asynchronism of male meiotic progress of PMCs in the same bud was observed in P. canescens, 56.33% 2n pollen could be achieved when the PMCs were exposed to high temperature at diplotene to diakinesis. The highest triploid production rate was 10.71%. Our findings suggested that it was possible to produce triploid by induced pollen chromosome doubling by high temperature exposure and obtained triploid P. canescens for the first time.

Key words: Populus canescens, pollen mother cells, high temperature exposure, pollen chromosome doubling, triploid