马鹿花光合和水分生理生态特性的日变化

 为研究马鹿花光合参数的日变化规律及其与空气相对湿度RH、大气CO₂浓度C_a、大气温度T_a、叶温T_l、光合有效辐射PAR、叶面水汽压亏缺VPD等主要影响因子间的关系,使用Li-6400便携式光合测定仪对马鹿花光合作用和水分生理生态特征参数进行测定.结果表明,马鹿花净光合速率P_n的日变化呈双峰型,峰值分别出现在12:00前后和16:00前后,出现"光合午休"现象；蒸腾速率T_r呈单峰型,在16:00达到峰值；水分利用效率WUE呈双峰型,上午高于下午.P_n对PAR、T_a和RH的响应程度不同,但均达到显著水平.马鹿花各参数间存在复杂的相关性,随着蒸腾速率增大,气孔导度增大,胞间CO₂浓度减小,净光合速率升高,且影响马鹿花P_n下降的因素主要是非气孔因素.

Daily Variations of Photosynthesis Parameter and the Effect of Environmental Factors on Pueraria wallichii DC.

For a general study of the daily variation regulation on the photosynthetic parameters and its relation with the main impact factors about relative humidity RH, atmospheric CO₂ concentration C_a, atomspheric temperature T_a, leaf temperature T_l, photosynthetic active radiation PAR, vapor pressure deficit on leaf VPD of Pueraria wallichii DC., photosynthesis and water physiological characters of P. wallichii DC. on the Ordos plateau during the growth season were measured using LI-6400 portable photosynthesis system. The results showed that the net photosynthetic rate P_n of P. wallichii DC. had a diurnal change with two peaks at 12:00 and 16:00, exhibiting an obviously phenomena of photosynthetic midday depression. The transpiration rate T_r took on a curve with only one peak, which reached the highest value at 16:00. The water use efficiency WUE had a diurnal change with two peaks and it was higher in the morning than in the afternoon. The responsiveness of P_n to PAR, T_a and RH was different and significant. This result shows that there is the complicated relation among the parameters of coefficient, with increase of net photosynthetic rate, increase of transpiration rate, increase of stomatal conductance, decrease of intercellular CO₂ concentration, and the decline of red deer spend P_n is not mainly affected by stomatal factors.