Photosynthetic characteristics of protected plant Alcimandra cathcardii seedlings of three habitats (wasteland, underforest, nursery) in Gaoligong Mountains southern section were measured by three successive days using Li-6400XT Portable Photosynthesis System.The results showed that: ①the diurnal courses of net photosynthetic rate, transpiration rate, stomatal conductance of seedlings under three habitats had no "midday depression", and the highest at 9: 00-11: 00;the diurnal courses of intercellular CO2 concentration was opposite to the net photosynthetic rate;water use efficiency had no significant change in the law.②By correlation analysis, the net photosynthetic rate was influenced by environmental factors: light intensity, relative humidity, air temperature, atmospheric CO2 concentration.According to descending order, seedlings of wasteland: light intensity, relative humidity, air temperature, atmospheric CO2 concentration;seedlings of underforest: light intensity, air temperature, relative humidity, atmospheric CO2 concentration;seedlings of nursery: light intensity, relative humidity, atmospheric CO2 concentration, air temperature.③Light saturation point of wasteland seedlings was (1284.96±48.231)mol·m-2·s-1, underforest seedlings was (1052.31±24.746)μmol·m-2·s-1, nursery seedlings was (1255.62±52.374)μmol·m-2·s-1, light compensation point were (28.65±1.904), (17.09±0.828), (6.75 ±0.317)μmol·m-2·s-1, after the light saturation point, the three appeared caught inhibition;④CO2 response curves varied greatly, the highest was wasteland seedlings, three CO2 saturation point was not obvious, the compensation point of wasteland seedlings was (103.75±6.826)μmol·m-2·s-1, underforest seedlings was (102.67±5.081)μmol·m-2·s-1, nursery seedlings was (130.1±2.022)μmol·m-2·s-1, therefore, there were nuances for the photosynthetic characteristics of seedlings under different habitats, and the nursery environment were the best.%用Li-6400XT便携式光合仪对高黎贡山南段3种生境(荒草地、林下、苗圃)中生长的国家Ⅰ级保护植物长蕊木兰幼苗进行连续3d的光合特性测定,为其科学保护提供一定依据.结果显示:①3种生境下的幼苗净光合速率、蒸腾速率、气孔导度日变化未见"午休"现象,9:00-11:00所测值为1d中最高;水分利用率无明显变化规律;胞间CO2摩尔分数与其他光合参数日变化相反.②相关性分析显示,光合有效辐射、相对湿度、空气温度、大气CO2摩尔分数对幼苗净光合速率的影响为,荒草地幼苗从大到小依次是光合有效辐射、相对湿度、空气温度、大气CO2摩尔分数;林下幼苗从大到小依次是光合有效辐射、空气温度、相对湿度、大气CO2摩尔分数;苗圃幼苗从大到小依次是光合有效辐射、相对湿度、大气CO2摩尔分数、空气温度.③荒草地幼苗光饱和点为(1284.96±48.231)μmol·m-2·s-1、林下幼苗(1052.31±24.746)μmol·m-2·s-1,苗圃幼苗(1255.62±52.374)μmol·m-2·s-1;光补偿点分别为(28.65±1.094)、(17.09±0.828)、(6.75±0.317)μmol·m-2·s-1,饱和点后,三者均出现抑制现象.④CO2响应曲线差别较大,其中荒草地幼苗最高,三者CO2饱和点不明显,补偿点分别为荒草地幼苗(103.75±6.826)μmol·m-2·s-1、林下(102.67±5.081)μmol·m-2·s-1、苗圃(130.1±2.022)μmol·m-2·s-1,说明不同生境下的幼苗光合特性存在细微差别,苗圃环境下光合特性最强.
展开▼
