皇甫川流域梁地生境中间锦鸡儿不同龄级植株光合生理特性的比较研究

对内蒙古鄂尔多斯市准格尔旗皇甫川流域梁地生境人工栽植的中龄级（5年生）和老龄级（24年生）中间锦鸡儿植株的光合生理特性进行了比较研究。结果表明：中龄级植株的净光合速率和蒸腾速率均大于老龄级植株；两个龄级植株在12:00~14:00净光合速率均下降，老龄级植株是由于光抑制使光系统Ⅱ受损、细胞光合能力下降等非气孔因素所导致，而中龄级植株是气孔因素和非气孔因素共同作用的结果，其中气孔因素是主要因素。光合色素含量的测定结果显示，中龄级植株的叶绿素含量、类胡萝卜素含量均显著高于老龄级植株，前者具有更高的净光合速率和光能利用效率，并且具有更高的抵御强光能力。中龄级植株的水分利用效率高于老龄级植株，具有更强的耐旱能力。

A Comparative Study of Photosynthetic Characteristics of Caragana davazamcii Between Plants of Different Ages in Huangfuchuan Basin of Ordos Plateau

The photosynthetic characteristics of Caragana davazamcii plants of different ages were investigated. The net Photosynthetic rate(P_n) and transpiration rate(T_r) of mid-aged plants(5 years old) were higher than those of senile plants(24 years old). The decrease of P_n in senile plants between 12:00-14:00 was caused by non-stomatal factors that impaired photosystem Ⅱand photosynthetic capacity of the leaves, while that in mid-aged plants was a consequence of both stomatal and non-stomatal inhibition. The determination of photosynthetic pigment contents showed that the contents of chlorophyll and carotenoid in mid-aged plants were significantly higher than those in senile plants, so that the mid-aged plants had higher P_n, LUE and capcity of intensive radiation adaptation. In addition, the mid-aged plants had higher WUE, which made them more tolerant to drought, so the mid-aged plants were able to adapt to the local envioronments with high temperature and severe drought.