大血藤叶的生长及光合生理生态特性研究

对大血藤叶的生长及光合生理生态特性进行了研究,结果表明:大血藤叶的长度、面积和干重的增加有共同的趋势,即在叶的生长早期增长很快,以后逐渐降低,叶长度、面积约在7月中旬达到最大值,叶干重8月初达到最大值。随着叶的生长,叶绿素含量、硝酸还原酶活力逐渐增加,至8月达到最大值,以后逐渐下降。春、夏期间的光补偿点低于秋季,而光饱和点则高于秋季。叶的光合日进程在春季呈"单峰"曲线;在夏、秋季则呈"双峰"型,有明显的"午休"现象。日均净光合速率在整个生长季节的变化是随着叶的生长,先是上升,至8月初达到最大值,然后逐渐下降。夏季,大血藤日均净光合速率比常绿阔叶树种低,比落叶阔叶树种高。

STUDIES ON CHARACTERISTICS OF LEAVES GROWTH AND PHOTOSYNTHESIS PHYSIOECOLOGY OF SARGENTODOXA CUNEATA

Studys on characteristics of leaves growth and photosynthesis physio ecology of Sargentodoxa cuneata showed that there were same increasing tendency among leaves length、area and dry weight of Sargentodoxa cuneata. They increased rapidly in early growth phase, but increased slowly after then. Leaves length and leaves area was maximum in the middle of July. Leaves dry weight was maximum at the beginning of August. The increasing of chlorophyll content and nitrate reducase activity with leaves growth lasted to August, reversed after then. The light compensation point in spring and summer was lower than in autumn, but the light saturation point was opposite. The diurnal variation of Pn was "single-peak" curve in spring, which was "twin-peak" curve showing obvious "noon-rest" in summer and autumn. The increasing of daily average of Pn in whole growing seasons lasted to the beginning of August, reversed after then. In summer, daily average Pn of Sargentodoxa cuneata was lower than evergreen broad-leaf species, which was higher than deciduous broad-leaf species.