绒毛番龙眼对生长光强的形态和生理适应

在100％、50％、25％和8％自然光强下栽培绒毛番龙眼幼苗并研究了其对光环境的适应。100％生长光强下绒毛番龙眼通过增大叶片悬挂角(midrib angle,MA)和比叶重(lamina mass per unit area，LMA)，减少叶氮在捕光组分中的分配等降低光能捕获；通过增加类胡萝卜素含量增加热耗散。虽如此，还是发生了比较严重的光抑制，加之叶氮在光合机构中的分配最少，导致光合能力最低，长势最差。8％生长光强下绒毛番龙眼通过降低MA、LMA以及叶片技转，增加叶氮在捕光组分中的分配等提高光能捕获能力，光能转换及利用效率较高，热耗散水平较低，但由于环境光较弱，限制了光合碳同化，植株生长也较慢。50％和25％生长光强下绒毛番龙眼有较强的光能捕获、利用和耗散能力，在几种光处理中长势最好。

Morphological and Physiological Acclimation to Growth Light Intensities in Pometia tomentosa

Acclimation to growth light environment was explored under 100%, 50%, 25% and 8% daylight for seedlings of Pometia tomentosa . Under 100% daylight P.tomentosa could reduce light interception through increasing leaf midrib angle (MA) and lamina mass per unit area (LMA) (Fig.1), and through decreasing leaf nitrogen allocation to light harvesting pigment complex (Fig.4), and increase heat dissipation through increasing carotenoid content (Figs.3 and 5). Even so, severe photoinhibition occurred under that condition (Fig.5). In addition to photoinhibition, the ratio of leaf nitrogen allocated to photosynthetic apparatus was the smallest among the four kinds of light treatments (Fig.4). All those were associated with the lowest maximal photosynthetic rate ( P max ) and with the worst growth performance under 100% daylight. Under 8% daylight P.tomentosa could increase light interception through decreasing MA, LMA, and leaf turning (Fig.1), and through increasing leaf nitrogen allocation to light harvesting pigment complex (Fig.4). Compared to other light treatments, under 8% daylight the efficiency of light energy conversion and light utilization were higher, while excess light energy and heat dissipation were lower (Fig.5). But electron transport rate was lower due to lower light intensity (Fig.5). The shortage of light energy limited carbon assimilation, and growth performance of P.tomentosa under 8% daylight. Under 50% and 25% daylight the ability to intercept, utilize and dissipate light energy was higher in P.tomentosa , so P.tomentosa could grow best. In conclusion, MA, LMA and leaf nitrogen allocation in different part of photosynthetic apparatus played important roles in acclimation to growth light environment in P.tomentosa , the roles of other physiological variables measured in this study were small, and their changes were mainly caused by LMA.