生态沟渠铜钱草光合日变化的研究

Diurnal photosynthetic changes of Hydrocotyle vulgarisin the ecological ditch

以生态沟渠铜钱草为材料,采用便携式CID-340光合仪对铜钱草成熟叶片净光合速率(Pn)以及胞间CO2浓度(Ci)、光合有效辐射(PAR)、气孔导度(Gs)、气温(Gs)、叶温(Tl))和蒸腾速率(Tr)等影响因子进行测定,以探讨其光合生理生态特性,旨在为修复沟渠湿地提供一定的理论依据。结果表明:(1)铜钱草叶片净光合速率(Pn)日变化曲线呈双峰型,主峰(19.32μmol.m-2.s-1)出现在15:00左右,次峰(16.21μmol.m-2.s-1)出现在11:00,中午出现光合"午休"现象。(2)用逐步多元回归方法得到净光合速率日变化与主要生理生态因子的回归方程为:Pn=-5.45613+0.006797PAR+0.050099Gs(复相关系数0.868)。逐步回归结果表明Pn受PAR和Gs的影响较大。偏相关分析和通径分析的结果表明PAR、Gs对铜钱草Pn日变化有重要影响,是影响铜钱草Pn的主要因子,影响大小的顺序为:Gs>PAR。

CID-340 Portable photosynthetic system was employed to measure the net photosynthetic rate,intercellular carbon dioxide concentration, photosynthetically active radiation, stomatal conductance, atmospheric temperature around the leaves, leaf temperature, and transpiration rate of Hydrocotyle vulgaris to study the photosynthetic characteristics in ecological ditch. The objective was to provide theoretic bases for ditch wetland restoration. The results were as follows： （1）The net photosynthetic rate of Hydrocotyle vulgaris changed in a double-peak curve with its peaks occurring separately at 11：00（16.21 μmol·m-2·s-1 ） and 15：00（19. 32μmol·m-2·s-1 ） ,which indicated a photosynthetic ＂mid- day depressions＂ at noon. （2）The regression equation of the diurnal variation of Pn and its major physi-ecological factors attained by the method of stepwise multiple-regression was as follows： Pn =-5. 45613 ＋ 0. 006797PAR ＋ 0. 050099Gs （multiple correlated coefficient 0. 868）. The results indicated that stomatal conductance（Gs）and transpiration rate（ Tr ） were the important factors that affected Pn. The analysis of partial correlation and path on Pn and factors showed that the diurnal variation of Pn had significan impact with photosynthetically active radiation（PAR）and stomatal conductance（Gs）, were the important factors which affected Pn and he order of effecting ability was Gs〉PAR.