中国鹅掌楸天然群体与人工群体的生育力

Fecundity of natural and cultivated populations of Ltriodendron chinense(Hemsl.) Sarg.

中国鹅掌楸（Ｌｉｒｉｏｄｅｎｄｒｏｎｃｈｉｎｅｎｓｅ（Ｈｅｍｓｌ．）ｓａｒｇ．）５个地点的群体与个体的生育力３年（１９９１～１９９３）研究结果表明：饱满翅果率为０．４５～１２．７７％，饱满种子率为０．４５～１４．７６％。不同群体间生育率有显著差异，同一群体不同年份间可塑性极大，在一个群体中个体间、聚合果间以及聚合果内不同部位间饱满翅果数的方差份量分别是４９．４６％、３２．９６％和１７．５８％；种于数的方差份量分别为４４．５２％、３４．４０％和２１．０８％。饱满翅果数与总翅果数之间不存在负相关，说明生育力不受资源限制，生育力低的原因可能是花粉限制，通过交配系统的进化与选择以及环境压力而起作用，结果限制了其生殖成功。

ecundity of Liriodendron chinense (Hemsl.)sarg.from 5 localities for 3 years observation(1991～1993)is addressed. Overall full samara rate ranges from 0. 45%to 12. 77%and from 0. 45%to 14.76%for overall seed rate. Significant difference on fecundity indexes occurs among different populations,and great difference on fecundity indexes also exists in different years.Intra-population variance components of number of full samaras are analysed as follow:49.46%for individuals,32.96%for aggregate fruits ,and 17. 58% for different parts within a aggregate fruit.Similarly,intra-population variance components of number of seeds show a parallel pattern,e. g.44.52%, 34. 40%, and 21.08%. No negative correlation exists between number of full samaras and total number of samaras.It seems that the fecundity of this species is not resource-limited. Its low fecundity can be explained by pollen-limitation,which acts through evolution and selection of mating system as well as environment stretse, Thus,the reprOductive success is subsequently restricted.