Abstract:To investigate the pollination system and reproductive investment strategies of Salix dunnii, the floral characteristics of flower and catkin and population sex ratio were investigated, the visiting insects were collected and their visiting frequency was calculated, the fruit and seed sets were calculated by bagging test, the volatile components of catkin were determined by gas chromatography-mass spectrometry (GC-MS). The results showed that the sex ratio of population in Dongbian Village was significantly male-biased (♂∶♀=1.28∶1, P < 0.05), while it was in equilibrium in populations of Guodun and Gaodi Village. The catkin number of male branches was significantly higher than that of female branches (P < 0.05), and the male flowers per catkins were significantly more than female flowers (P < 0.001), but the average length of female catkins was notably longer than that of male catkins (P < 0.001). Salix dunnii was wind- and insect-pollination, Apis cerana was the main visitor, which showed significant preference to visit female individuals (P < 0.001). The relative content of β-caryophylene in female, which is attractive to A. cerana, was significantly higher than the male (P < 0.001). Furthermore, β-elemene and linalool were only identified in female catkins, which were attractive to honey bee too. Therefore, it was suggested that male S. dunnii allocated more resource in producing male flowers at flowering stage, which was probably beneficial for wind-pollination, while female plants fought against the "pollinator limitation" by increasing the variety and output of volatile to improve insect-pollination. Salix dunnii possibly improve the reproductive efficiency via the combination of wind- and insect-pollination.
