不同CO_2浓度对4个桤木品系光合特性的影响

Study on Photosynthetic Characteristics of Four Alnus cremastogyne Varieties under Different CO_2 Concentrations

对HI、H12、J5和J104个桤木品系苗期在不同CO2浓度条件下的光合生理生态特性进行了研究，结果表明：随着CO2浓度的增加，4个桤木品系净光合速率呈上升趋势，其CO2补偿点为39～154μmol·mol^-1，CO2饱和点为800～2000μmol·mol^-1，净光合速率最大值Pm以6月份最高，10月份最低；羧化效率（CE）介于0．0015～0．0515之间，HI、H12在7月份有较大的CE；4个桤木品系蒸腾速率（Tr）下降、胞问CO2浓度（Ci）上升，气孔导度（Cond）下降，光合特征值在10月份最低，可能是10月初突然降温、秋天干旱等对桤木生长有影响；叶面饱和蒸气压亏缺（Vp）随着CO2浓度的增加缓慢上升，增加幅度不大。

In order to utilize the superior varieties of Alnus cremastogyne scientifically, the photosynthetic character- istics of four Alnus cremastogyne families, H1, H12, J5 and J10, were studied under different CO2 concentrations at seedling stage. The results were as follows ： （ 1 ） With the increase of CO2 concentration, the net photosynthetic rate of four Alnus cremastogyne varieties showed ascending trend, their CO2 compensation point were from 39 txmol ~ mol^-1 to 154 μmol · mol^-1 , and their CO2 saturation point were from 800 μmol · mo1^-1 to 2 000 μmol· mol^-1. The high- est value of Pm showed in June, While the lowest in Octember; （2） With the increase of CO2 concentration, the carboxylation efficiency（CE） of four Alnus cremastogyne varieties were between 0.001 5 and 0. 051 5 ,and H1, H12 presented greater CE, So their high temperature tolerance ability was stronger than that of J5 and J10; while H12 showed stronger photosynthetic efficiency than H1 ; （3） With the increase of CO2 concentration, the transpiration rate （Tr） and stomatal conductance （Cond） decreased, while the intercellular CO2 concentration （Ci） increased. The lowest eigenvalue of Tr, Ci and Cond showed in October; and the performance of H12 and J10 was rather grea- ter than H1 and J5. So irragration in Autumn and drought-resistance variety selection played important role in growth of Alnus cremastogyne. （4） The vapor deflicit at the leaf surface of Alnus cremastogyne varieties increased slowly with the increase of CO2 concentration.