林下与全光下地枫皮叶片形态和光合特性的比较

测量了林下与全光下地枫皮的叶片形态和光合-光响应曲线,探讨光强对地枫皮的形态和生理特性的影响。结果表明：林下与全光下地枫皮叶片净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）和水分利用效率（WUE）对光强的响应趋势均基本一致,但全光下的Pn、Gs和Tr值较高,林下WUE值较高。全光下地枫皮的最大净光合速率、光饱和点和光补偿点均极显著高于林下,但弱光下的量子效率无显著差异;林下地枫皮的叶长、叶宽、干物质重、叶面积和比叶面积等叶片形态参数均极显著大于全光。推断地枫皮为耐阴性较弱的阳生植物,其光合能力和光饱和点较低,是对干旱环境的适应性反应;全光下地枫皮叶片狭小降低了吸光面积,有利于避免过高光强对叶光合器官的损伤。

Comparison on Leaf Morphological and Photosynthetic Characteristics of Illicicum difengpi K.I.B.et K.I.M Grown in Full Light and under Canopy

In order to evaluate morphological and physiological acclimation to growth light intensities,the leaf morphological parameters and Pn-PPFD response curves were measured in leaves of Illicicum difengpi K. I. B. et K. I. M. grown in full light and under canopy. The results showed that,the tendency of net photosynthetic rate （Pn）,stomatal conductance （Gs）,transpiration rate （Tr） and water use efficiency （WUE） in response to light were fairly consistent between I. difengpi grown in full light and under canopy. However,Pn,Gs and Tr were higher in full light than under canopy,and WUE was lower in full light than under canopy. Photosynthetic parameters of I. difengpi grown in full light,i. e. the maximal net photosynthesis rate,light saturation point （LSP） and light compensation point of were significantly higher than those of grown under canopy,but there＇s no significant difference between them in apparent quantum yield. The leaf morphological parameters such as leaf length,leaf breadth,leaf dry mass,leaf area and specific leaf area were significantly higher in I. difengpi grown under canopy than in full light. We concluded that I. difengpi is a sun plant with weak shade tolerance,relatively low photosynthetic capacity and LSP demonstrated its great ability to arid environment. Its leaves become reduced in size （becoming narrower） in full light,it is likely that this adaptive strategy reduces leaf surface area and hence reduces possible damage to photosynthetic structures.