关键词: 华北落叶松, 传粉, 种子产量

Abstract:

For Larix principis-rupprechtii Mayr.the distribution of male and female cones in crowns,pollen density around trees,pollination mechanism and pollen grains accepted by ovules and seed products were studied.Female cones were mainly distributed on 2～4 aged branches in the middle and upper parts of a crown,while male cones on 2～7 aged branches in the lower and middle parts.The highest pollen density of middle part was observed.The pollen density around crown was related with the distribution of male cones.According to the morphology change of female cones,the pollination period might be divided into five stages.Pollen grains were captured by stigmatic hairs without pollination drop.The optimal pollination period for ovules capture continued about two days.Four pollen grains or so were found in each ovule on average.Although there was a certain relationship between the numbers of pollen grains accepted by ovule and the production of full seeds, it was not the essential reason for causing the emptied seeds.In addition,the effects of open,supplementary and control pollination methods on the seed production and the significance of defining the optimum time of pollination for increasing seed production were discussed.

Key words: Larix principis-rupprechtii, Pollination, Seed production