湿地松等3种树种的光合特性及其与环境因子的关系

Photosynthetic characteristics of Pinus elliottii,Elaeocarpus sylvestris and Myrica rubra and their relationship with ecological factors

采用红外线二氧化碳分析仪闭路气流法于夏季晴天测量湿地松、杜英和杨梅等的光合特性和光合日进程 ,并同步测定光合有效辐射强度、气温和空气相对湿度对光合日进程的影响。研究结果如下 :湿地松、杜英和杨梅的光补偿点分别为 86,34和 45 μmol·m-2 ·s-1;饱和点分别为 1 2 0 0 ,760和 1 0 5 0 μmol·m-2 ·s-1;表观量子产额分别为 0 0 2 0 3,0 0 5 31和0 0 388;最大净光合速率分别为 7 1 5 ,1 2 5 0和 7 85 μmol·m-2 ·s-1。根据对光补偿点、饱和点、表观量子产额和最大净光合速率的分析 ,湿地松、杜英和杨梅均为阳性植物 ,湿地松对光强的生态适应范围最广 ,对强光的适应性最强 ,杜英对光强的生态适应范围偏窄 ,对弱光的利用效率最高 ;它们的光合日进程曲线为双峰曲线类型 ,存在“光合午休”现象 ,光合午休可能是高温和低湿造成的。通径分析表明 ,对湿地松和杨梅光合日变化直接影响最大的生态因子是气温 ,其次是空气相对湿度和光合有效辐射强度 ;对杜英的光合日变化影响较大的生态因子是空气相对湿度和气温。图 2表 3参 1

The photosynthetic rate and diurnal changes of Pinus elliottii,Elaeocarpus sylvestris and Myrica rubra were measured by closed circuit airflow method with carbon dioxide infrared analyzer in sunny days of July,2000.Photosynthetic active radiance,air temperature and relative humidity were determined.The results was as follows:Light compensation points of Pinus elliottii , Elaeocarpus sylvestris and Myrica rubra were 86,34 and 45 μ mol·m -2 ·s -1 ,respectivey.Their light saturation points were 1 200,760 and 1 050 μmol·m -2 ·s -1 ,respectively.Their apparent quantum yields were 0 020 3,0 053 1 and 0 038 8,respectively.Their maximum net photosynthetic rates were 7 15,12 50 and 7 85 μmol·m -2 ·s -1 ,respectively.By analysis on light compensation point and saturation point, Pinus elliottii , Elaeocarpus sylvestris ,and Myrica rubra were thought of as heliophilous plant,of which, Pinus elliottii was the hightest in adaptability to strong light,and Elaeocarpus sylvestris was the highest in use efficiency for weak light.Their curves of diurnal changes in photosynthetic rate were double peaked,and the photosynthetic depression at midday was caused by high temperature and low relative humidity.Path analysis showed that the most significant ecological factor directly affecting photosynthetic diurnal changes of Pinus elliottii and Myrica rubra was air temperature,followed by air relative humidity and photosynthetic active radiance.The more significant ecological factors affecting photosynthetic diurnal changes of Elaeocarpus syvestris were air relative humidity and air temperature.