马鹿花光合和水分生理生态特性的日变化

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

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Ca、大气温度Ta、叶温Tl、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Pn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Tr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。Pn对PAR、Ta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Pn下降的因素主要是非气孔因素。

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 Ca, atomspheric temperature Tl, leaf temperature Tl, 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 Pn of P. wallichii DC. had a diunaal change with two peaks at 12：00 and 16：00, exhibiting an obviously phenomena of photosynthetic midday depression. The transpiration rate Tl took on a curve with only one peak, which reaehed 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 Pn to PA R, Ta 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 Pn is not mainly affected by stomatal factors.