甜茶光合日变化及其与环境因子的关系

Study on the Diurnal Variation of Photosynthesis for Rubus suavissimus S.Lee and Its Relation to Environmental Factors

用Li-6400便携式光合测定系统对甜茶的光合-光强响应曲线和光合日变化进行了测定。结果表明:100%光下甜茶的光饱和点、光补偿点与最大净光合速率均显著高于30%光下的值,但2种光下甜茶的表观量子效率值均较低,且无显著差异,说明甜茶强光下的光合能力较强,但对弱光的利用效率较低。全光下甜茶的净光合速率(Pn)日进程呈双峰型曲线,中午前后Pn的下降与此时的强光、高温和低湿度有关,但非气孔限制是主要限制因素。逐步多元回归和通径分析表明,光合有效辐射、气温、叶温和空气湿度是直接影响净光合速率日变化的主要因子。因此,甜茶适宜种植在阳光充足的环境,但夏季适度遮荫利于其生长。

The Pn-PPFD response curves and diurnal variation of photosynthesis of Rubus suavissimus S. Lee were measured with the Li-6400 portable photosynthesis measuring system. The results showed that the maximal net photosynthesis rate,light saturation point and light compensation point of R. suavissimus were significantly higher in full light than in 30% light transmittance. Both their apparent quantum yield were low, and there＇s no significant difference between them. Indicating that it＇s photosynthesis capacity was higher in high light intensity, but it＇ s quantum yield was lower in low light intensity. Diurnal variation in net photosynthetic rate（Pn）of R. suavissimus was two-peak pattern. The rapid reduction in P, during noontime was related to strong light intensity, high temperature and low air relative humidity,and the most important of which was non-stomatal restriction. The analysis of stepwise multi-regression and path coefficient showed that the photosynthetically active radiation, ambient temperature, leaf temperature and air relative humidity were the main direct factors which affected the diurnal variation of Pn. In summary,R, suavissimus adapted to a moderately sunny environment, but moderate shading was beneficial to the growth and developmentof the plant in summer.