橡胶树大筒苗培育方法VII.遮阴率的筛选

为了解不同遮阴环境下橡胶树(Heveabrasiliensis)大筒苗的生长及光合特性，明确大筒苗生长的适宜光照环境，以小苗芽接苗和组培苗为胚苗的橡胶树大筒苗为材料，设置5个遮阴处理：CK (全光照)，S60、S70、S80和S90 (分别为60%、70%、80%、90%遮阴率)，观测其出圃时的生长指标和光合参数变化情况。结果表明，不同遮阴率对橡胶树大筒苗的生长、光合参数及出圃时顶蓬叶的叶面积和叶绿素相对含量均有极显著影响，且2种胚苗间差异显著。大筒苗的壮苗指数随遮阴率的增加呈现先增后降的趋势；与全光照相比，遮阴显著影响大筒苗的出圃率，但对定植成活率的影响较小；胚苗类型与遮阴处理的交互作用明显。全光照和过度遮阴(S90)均会明显抑制大筒苗的生长，不同胚苗的大筒苗最适遮阴率不同，小苗芽接苗大筒苗在S60、组培大筒苗在S80下的生长表现最好。因此，橡胶树大筒苗培育时应根据不同的胚苗类型选择适宜的遮阴措施。

Cultivation Method of Hevea brasiliensis Large Polytube-raised Buddings VII. Screening of Shading Rate

To understand the growth and photosynthetic characteristics of large polytube-raised buddings of Hevea brasiliensis under different shading environments, and to determine the appropriate light environment for the growth of large polytube-raised buddings, five shading were set, including CK (full light), S60, S70, S80 and S90 (60%, 70%, 80% and 90% shading rate, respectively), to observe the growth index and photosynthetic parameters changes. The results showed that different shading rates had significant effects on the growth, photosynthetic parameters, leaf area and relative content of chlorophyll of top-leaf-whorls of large polytube-raised buddings of H. brasiliensis, and there were significant differences between the two types of embryo seedlings. The vigorous seedling index of large polytube-raised buddings increased at first and then decreased with the increase of shading rate. Compared with full light, shading significantly affected the out-nursery rate of large polytube-raised buddings, but had little effect on the survival of planting. The interaction between embryo seedling type and shading was obvious. Full light (CK) and excessive shading (S90) could significantly inhibit the growth of large polytube-raised buddings. The optimal shading rate of large polytube-raised buddings was different among different embryo seedlings. The growth performance of small seedling buds under S60 and tissue culture seedlings under S80 was the best. Therefore, appropriate shading measures should be selected according to embryo seedling types during the cultivation of large polytube-raised buddings of rubber trees.