董棕和短穗鱼尾葵光合效率日变化及其与生理生态因子的关系

利用美国产CI-340便携式光合测定系统,对董棕和短穗鱼尾葵的光合日变化特性进行了测定,通过相关分析和通径分析探讨净光合速率与生理生态因子的关系,并利用二项式数学模型对其光合光响应曲线进行了拟合.结果表明:(1)2种棕榈植物的净光合速率日变化都呈现不对称的双峰曲线,有明显的"午休"现象,董棕的午休深度及时长明显大于短穗鱼尾葵,其第二峰出现的时间比短穗鱼尾葵延后2h,这可能主要由于两者在气孔导度及蒸腾速率等自身生理因子活性方面的差异所致.(2)影响董棕和短穗鱼尾葵净光合速率日变化的主要决定生理因子均为胞间CO2浓度,但主要限制因子董棕为气孔导度,短穗鱼尾葵为叶面温度;主要决定生态因子董棕为光合有效辐射,短穗鱼尾葵为空气CO2浓度,主要限定因子两者均为空气相对湿度.(3)董棕和短穗鱼尾葵均具有较高的光补偿点和光饱和点,属强耐阳性植物,但鱼尾葵相对较低,更适于北移引种栽培.

Photosynthetic Dynamic Variation and Its Relationship with the Eco physiological Factors in Caryota urens and Caryota mitis

The photosynthetic characters were observed with CI-340 portable photosynthesis determination system produced by United States.The relationships of Pn and eco-physiological factors were analyzed with path coefficient and the light-response curve was fitted with parabola model for Caryota urens and Caryota mitis.The results showed as follows:(1)The net photosynthetic rate of two species presented asymmetric double peak curve,with a clear "midday depression",and its length and depth in C.urens was more obvious than that in C.mitis,and the minor peak in C.urens was also delayed about 2 hours.These differences maybe result from the various activities of physiological factors such as stomatal conductance and transpiration rate and so on.(2)Ci is the main physiological factor affecting the characteristic of Pn of two species.However,Gs was the main limiting factor in C.urens,Tleaf in C.mitis;The main ecological factor was PAR in C.urens,Cair in C.mitis and RH was the limiting factor of two species.(3)The light-response curve of two species was fitted with parabola models.The high LCP(light compensation point) and LSP(light saturation point) in two species showed that they all belonged to strongly light plant.However,these values were higher in C.urens than that in C.mitis.Thus,the latter was more adaptive to be removed from south to north.