光诱导下杂种杨无性系叶角和叶绿体的运动

自然光结合人工光源对几个杂种杨无性系叶片进行处理后，对其在两种光环境下３种叶角（方位角、方向角、悬挂角）和叶绿体的运动方式进行了研究。结果发现：各无性系的叶角运动在晴天比比阴天强烈，特别是三倍体无性系最为明显，晴天上午９：００－１１：００，三倍体无性系ＺＨ６和Ｂ３４６通过方位角运动来避免强光胁迫，各无性系主要通过方向角和悬挂角的变化来调节获得最佳太阳辐射，在中午受到强光胁迫时存在明显的“避光运动”。三倍体无性系和某些二倍体无性系在避光运动方式上是不同的，三倍体无性系ＺＨ６和Ｂ３４６采用叶片下垂形式，而二倍体无性系Ｂ１１则采用叶片竖立方式，无论是晴天还是阴天，植物的节律性运动可能参与了叶角运动。受光胁迫时，栅栏组织的叶绿通过不同的运动排列方式来实现对光辐射的最佳吸收。强光胁迫下叶绿体沿径向细胞壁排列，以尽量养活接受过量的太阳辐射，处于弱光条件时，叶绿体则充满足整个细胞，以扩大上太阳辐射的表面积，三倍体无性系对光诱导的敏感程度程度要高于二倍体无性系。

Light induces leaf orientation and chloroplast movements of hybrid poplar clones

Diurnal changes in leaf azimuth angle,lamina angle,midrib angle under two natural regimes and chloroplast movements when subjected to different light pretreatments were investigated for several hybrid poplar clones.Changes in leaf orientation in a clear day were stronger than that in a cloudy day especially for triploid clones,suggesting these clones were sensitive to light.From 9:00 to 11:00 in the clear day,the triploid clones ZH6 and B346 evaded strong light by changing in azimuth angle.Around midday hours light evasion movements could be achieved by changing midrib angle,declining leaf tilt downwards for triploid clones ZH6 and B346 and maintaining leaf blade erected for diploid clone B11.In other daytime all clones optimize in interception of solar irradiance by changing both of midrib angle and lamina angle.In both clear and cloudy days,rhythmical movement involved in change of lamina angle.The chloroplasts in the palisade cell moved and lined along the radial wall of cell when subjected to strong irradiance,which made the chloroplasts have less areas to expose direct light.Whereas the chloroplasts in the palisade cell distributed all over the cell when receiving darkpretreatment,which made the chloroplasts have much more areas to receive direct light.The triploid clones were more sensitive to light induction than that of diploid clones in the movements of leaf and chloroplast.