粤西乡土香根草光合生理生态特征日动态分析

Diurnal change of photosynthetic characteristics of native Vetiveria zizanioides in Western Guangdong.

在秋季对粤西乡土香根草的光合等生理特性日动态变化进行了测定.结果表明,香根草的净光合速率(Pn)日变化呈双峰型,蒸腾速率(Tr)和气孔导度(Gs)变化趋势与Pn相似,胞间CO2浓度(Ci)变化方向则与其相反.Pn与光合有效辐射(PAR)、Tr与PAR、Ta和大气相对湿度(RH)的相关程度都达到了极显著水平(P<0·01),Gs则与空气温度(Ta)相关程度达到了显著水平(P<0·05).同一环境因子对Pn、Tr和Gs的影响程度不同,其中PAR是影响香根草光合作用最为强烈的环境因子.Tr是受环境因子控制最为显著的生理参数.

The determinations on the photosynthetic parameters of native Vetiveria zizanioides in Western Guangdong in autumn showed that the net photosynthetic rate （ Pn ） of V. zizanioides had a diurnal change with two peaks, transpiration rate （ Tr ） and stomatal conductance （ Gs ） were similar with Pn, while intercellular CO2 concentration （ Ci ） was in adverse. There was a significant positive correlation between P, and photosynthetic active radiation （PAR） （ P 〈 0.01 ）, Tr and PAR （ P 〈 0. 01 ）, air temperature （ Ta ） and relative humidity （ RH ） （ P 〈 0. 01 ）, and G and Ts （ P 〈 0. 05 ）. Same environmental factors had different effects on Pn, Tr and Gs, and PAR had most intensive effect on the photosynthesis of V： zlzanioides. Among the test photosynthetic parameters, Tr was most sensitive to the environmental factors.