开花位置和开花时间对华北驼绒藜结实率及种子千粒重的影响

本研究对华北驼绒藜(Ceratoides arborescens)生长4年和生长8年居群不同冠层、株丛上主枝和一级侧枝，以及不同花期花的结实率和种子千粒重进行了测定和分析。结果显示，1）株龄较小的植株结实率较高，所结种子千粒重较大，可能与年龄小的植株分枝少，养分集中有关。2）结实与花在花序上的位置有关。无论在主枝条上还是在侧枝上，先开花的部位结实率高，种子千粒重也较大。3）对整个居群来说，冠层的中层结实率最高，种子千粒重最大，冠层下层结实率和种子千粒重最小。4）盛花期开的花结实率高，种子千粒重也大，末花期次之，始花期花的结实率最低，种子千粒重也最小。

Influence of floret position and flowering time on seed set and thousand seed weight of Ceratoides arborescens

Some fruiting characters in 4 years old and 8 years old of Ceratoides arborescens populations were investigated in this study by determining the relationship between floret position and flowering time on seed set and thousand seed weight.The results of this study showed that the seed set rate and thousand seed weight of younger plants were higher than that of older plants because the younger plants had less branches than older plants,which wa beneficial to nutrients concentration.The seed set was related to the floret position and flowering time,indicating that the seed set rate in part of the inflorescences that flowered earlier was higher than that in the part that flowered later,and the thousand seeds were showed a simlar trend.As far as the whole population was concerned,the seed set rate and thousand seed weight in the middle layer of the canopy was the highest,and those in the lower layer of the canopy was the least.Those flowered in profuse flowering phase had the highest oppotunity to fruit,and their seeds were the heaviest,but those flowered in early flowering phase had the least opportunity to fruit,and their seeds were also lighter than those flowered later.