TUBE POLLINATION USING STORED POLLEN FOR CREATING ACACIA AURICULIFORMIS HYBRIDS

Artificial pollination using polyvinyl tubes, a recognised pollination method for the genus Acacia, was conducted to determine whether this method was also suitable for the establishment of Acacia hybrids (A. auriculiformis × A. mangium) using stored pollen. This method was used to cross female adults of A. auriculiformis with males of A. mangium, with intraspecific pollination of A. auriculiformis conducted as the control. In this method, pollen was first collected by inserting a tube into spikes of male adults immediately after flowering. The tube was then stored at -18 °C for either one day, one month or two months. The germination rate of A. mangium pollen was 17% following storage for one day but increased to greater than 40% following storage for one or two months. In contrast, the germination rate of A. auriculiformis pollen exceeded 40% regardless of the storage duration. Artificial pollination was conducted by inserting the stored tube with pollen into flowering spikes of A. auriculiformis. Results of interspecific pollination showed that an average of three hybrid seedlings was acquired per pollination using pollen stored for one day, and was greater than five when pollen stored for one or two months was used. However, DNA analysis revealed that 2.6% of seedlings were contaminated by A. auriculiformis. In contrast, less than three seedlings were acquired per intraspecific pollination regardless of the duration of pollen storage. These results suggest that this tube method is a suitable procedure for the establishment of A. auriculiformis hybrids using stored pollen.