不同立地条件罗汉果组培苗的光合特性

比较了三种不同立地条件罗汉果组培苗的光合光响应特性以及主要环境因子和光合生理参数的日变化,从光合作用的角度探讨影响罗汉果组培苗生长的关健生态因子。结果显示:罗汉果组培苗的光饱和点和补偿点均随海拔的增高而增大;丘陵的最大净光合速率最高,山地最低。丘陵和山地罗汉果组培苗的净光合速率(Pn)日变化曲线呈"双峰"型,在12:30～13:30时出现轻微的非气孔限制,平地受云层遮挡,无第二峰出现;9:00～15:30时之间的罗汉果组培苗Pn与气孔导度(Gs)正相关,而Pn和Gs均与光量子通量密度(PFD)、叶温(TL)和叶片内外水汽压差(VPD)负相关,并随TL和VPD的增大下降幅度更大。丘陵环境条件最适合罗汉果组培苗的生长,中午前后Pn的下降与此时的强光、高温和低湿度有关,是气孔限制和非气孔限制同时作用的结果。

Photosynthetic characteristics of tissue culture plantlet of Momordica grosvenorii planted in different habitats

The experiment was conducted to clarify the key ecological factors affecting the growth of Siraitia grosvenorii. Responses of net photosynthetic rate to photon flux densities,diurnal course of main environmental factors and physiological characteristics in S.grosvenorii tissue culture plantlet planted in three different habitats,and the relationship between them were analyzed. The results showed that,with the increase of altitude,the light saturation point and light compensation point of S.grosvenorii increased,the maximum net photosynthetic rate was the highest at hilly region,and was the lowest at mountainous region. The diurnal variation of net photosynthetic rate (Pn) at hilly region and mountainous region were "twin-peaked" curves,and the decrease of Pn from 12:30 to 13:30 was due to slight non-stomatal restriction,"the second peak" wasn’t observed at flat site for rapidly fluctuating irradiance levels from intermittent cumulus clouds. From 9:00 to 15:30,there was a relatively strong positive relation between Pn and stomatal conductance,a negative relationship between TL,VPD and photon flux densities(PFD),leaf temperature(TL),vapour pressure deficit(VPD)for S.grosvenorii tissue culture plantlet,and they declined faster with TL and VPD. Hilly region was the optimum growth environment for S.grosvenorii tissue culture plantlet. The rapid reduction in Pn during noontime was related to strong light intensity,high temperature and low relative humidity,and was the result of common effect of stomatal and non-stomatal restriction.