遮阴处理对土沉香幼苗生长和叶片解剖特征的影响

研究不同光处理（100%，50%，25%和5%自然光）对土沉香幼苗形态和解剖特征的影响，以了解土沉香幼苗叶片形态结构对光的适应规律。结果表明，不同光强对3个土沉香种源（大白、大黄和云南）的解剖结构和生长参数有不同程度的影响。随着光强的减弱，3个种源幼苗的主脉、叶厚、栅栏组织、叶上表皮细胞厚度总体上都呈显著下降的趋势（P<0.05），而海绵组织厚度呈上升趋势，叶片下表皮细胞厚度变化幅度不一；随着光强的减弱，3个种源的叶面积比和比叶面积升高，云南种的总生物量和绝对生长速率随之下降，而大白和大黄的总生物量和绝对生长速率在50%和25%光强下高于100%和5%光强下的值。除大黄的比叶重为50%高于其他光强下的值，大白和云南的比叶重以及3个种源的根重比均随着光强的减弱而下降。总之，3个土沉香种源幼苗在不同光强下通过其形态上的一系列改变来适应光环境，云南种在自然光强下（100%）生长良好，而大黄和大白在中光环境下（50%）生长最好。

Effects of shading on seedling growth and leaf anatomical characteristics of Aquilaria sinensis

In order to understand the light requirement and adaptability of Aquilaria sinensis（Lour.） Spreng， seedlings morphology and leaf anatomical characteristics of Aquilaria sinensis seedlings under different light treatments （100%， 50%， 25% and 5% natural light） were studied. The results showed that different shade treatments had different effects on the leaf anatomical structure and seedling growth parameters of three Aquilaria sinensis provenances （Dabai， Dahuang and Yunnan）. For all the three provenances， with the weakening of light intensity， the main veins， leaf thickness， palisade tissue thickness and leaf epidermal cells were generally decreased significantly （P<0.05）， the thickness of spongy tissue increased， and the lower leaf epidermis cell thickness showed varying change degrees. With the decrease of light intensity， leaf area ratio and leaf area increased in all the three provenances. For Yunnan provenance， the total biomass and absolute growth rate decreased as light intensity decreased， but for Dabai and Dahuang， growth parameter values under 50% and 25% light intensity were higher than that under 100% and 5% light intensity. The specific leaf weight and root weight ratio generally showed decrease trends with the decrease of light intensity in all the three provenances， except that the specific leaf weight of Dahuang in 50% light intensity was higher than other light treatments. In short， the seedlings of three Aquilaria sinensis provenances could make a series of changes in morphology to adapt to the light environment; Yunnan provenance had the best growth in natural light （100%），while Dabai and Dahuang were more suitable in moderate light intensity（50%）.