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.%本文研究了华北落叶松雌雄球花在树冠上的分布和树冠周围花粉密度变化规律、传粉机制、胚珠接收花粉量及结实状况等。雌球花主要分布在树冠中上部2～4龄枝上，雄球花分布范围较广，且常与雌球花混生；树冠周围花粉密度与雄球花的分布密切相关，中部最大，依次向上下两端减少。依据雌球花形态特征的变化，可将传粉期分为5个阶段，整个期间无传粉滴出现，由球被顶端大裂片的珠被毛接收花粉。最佳传粉期约为2天。胚珠平均接收4粒花粉，虽然胚珠接收的花粉数与饱满种子的产量有一定关系，但并不是造成空粒的主要原因。此外，讨论了不同授粉方式对种子产量的影响，及确定最佳可授期对提高种子产量的重要意义。
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