Abstract: [Objective] This study was aimed to studying the suitable conditions of in vitro pollen germination and the methods of pollen viability test for Acacia auriculiformis in order to provide a basis for hybrid breeding of A. auriculiformis and creating new breeding material by artificial pollination.[Methods] Pollen of A. auriculiformis was collected after 10:00 am on the next day of collection of flower clusters using the brush method. The pollen was germinated in vitro in conditions with different temperatures, the different concentrations of sucrose and boric acid, and suitable conditions for in vitro pollen germination of A. auriculiformis were chosen. Peroxidase method, I₂-KI method and in vitro pollen germination method were used to detect the pollen viability of A. auriculiformis, and the effectiveness of these methods was assessed.[Results] When the pollen was cultured at 28℃, germination rate was 71.99%, the average length of pollen tubes was 5.3 D (1D=the length of pollen grain), the average number of pollen tubes was 6.2, which were significantly higher than those of the other culture temperatures. When the culture medium contained 200 g·L^-1 sucrose, the pollen germination rate was 84.96%, the average length of pollen tubes was 5.8 D, the average number of pollen tubes was 6.2, which were significantly higher than those of the other sucrose concentrations. When the culture medium contained 300 mg·L^-1 boric acid, the pollen germination rate was 75.32%, the average length of pollen tubes could reach 4.8 D, the average number of pollen tube was 5.4, which were significantly higher than those of the other boric acid concentrations. A. auriculiformis pollen in the culture medium at 30℃ culture temperature with 200 g·L^-1 sucrose and 300 mg·L^-1 boric acid had a germination rate of 98.26%, and the length of pollen tubes could be up to 10 times of the composite pollen length, and 10 pollen tubes could be produced at most, significantly higher than other treatments. When cultured for 3 h, the pollen germination rate was 65.74%, when cultured for 6 h, the pollen germination rate was 90.5%, and for 24 h the pollen germination rate tends to be stabilized, reaching the maximum rate of 98.26%. By peroxidase method, pollen viability was 99.67%, by I₂-KI method it was 99%, and by in vitro pollen germination it was 98.15%. There were no significant differences among the viabilities detected by the three methods.[Conclusion] Among the different treatments of A. auriculiformis pollen, the pollen germinations were significantly different. The most suitable conditions for in vitro pollen germination of A. auriculiformis was 200 g·L^-1 sucrose and 100 mg·L^-1 boric acid and 30℃ culture temperature, in which the pollen germination rate was 98.26%. There were no significant difference among the pollen viabilities detected by peroxidase, I₂-KI and in vitro pollen germination. The results provide a theoretical basis for collection, storage, and viability test of pollen of A. auriculiformis, and also an important foundation for controlled artificial pollination and breeding new hybrid varieties of Acacia in the future.

Key words: Acacia auriculiformis, pollen collection, in vitro pollen germination, pollen viability test