不同光强下生长的亚热带树苗的光合-光响应特性的比较

Photosynthesis light response characteristics of subtropical tree species seedlings under different irradiances.

鼎湖山亚热带森林中的优势树种马尾松、荷木、黧蒴和黄果厚壳桂的幼苗 ,盆栽于 1 0 0 %、40 %和 1 6%的自然光下生长 1年 .利用氧电极离体测定叶片的光合 -光响应曲线 ,结果表明不同树种及同一树种不同生长光强处理之间差异明显 .比较最大净光合速率( Amax)、光补偿点、光饱和点、光抑制点及光能利用效率 ( QUE)等的变化可见 ,黄果厚壳桂为耐阴植物 ,对高光强的光合适应潜力为有限 ,1 0 0 %的自然光明显抑制其最大同化力 ;其余 3种植物均为喜光植物 ,其中马尾松的光合作用对遮阴的适应能力较差 ,而荷木和黧蒴则相对较强 .

Potted seedlings of Pinus massoniana, Schima superba, Castanopsis fissa and Cryptocarya concinna , the dominant tree species in Dinghushan subtropical forests, are grown under 100%,40% and 16% of natural illumination for one year, and their photosynthesis light response curves are determined with O 2 electrode under a series of light intensity from 0 to 2500 μmol quanta m -2 ·s -1 . The comparison of dark respiration rate (DRR), maximum net photosynthetic rate (Amax), quantum use efficiency (QUE), light compensation point (LCP), light saturation point (LSP) and photo inhibition point (PP) for the seedlings of these tree species under different irradiances shows that Cryptocarya concinna is shade tolerant and has a limited photosynthetic potential of acclimating high PFD. The Amax of its seedlings growing under 100% sunlight is about 58% of those growing under heavy shade (16% sunliht). Pinus massoniana, Schima superba and Castanopsis fissa are sun loving species with higher DRR, Amax, LCP, LSP and PP. For Pinus massoniana, its photosynthetic potential of acclimating low PFD is limited, while Schima superba and Castanopsis fissa show a relatively high photosynthetic potential of acclimating high and low PFD. The relationship between photosynthetic physiological characters of tree species and their succession status is also discussed.