青杨雌雄扦插苗光合作用日变化与叶绿素荧光参数特征

Characteristics of Chlorophyll Fluorescent Parameters and Daily Dynamics of Photosynthesis in Female and Male Populus cathayana Cutting Seedlings

以青杨雌雄扦插苗为对象,探究其叶绿素荧光参数和光合作用日变化特征。结果表明:青杨扦插苗的Pn、Tr和Gs日变化均呈"双峰"型曲线,有明显的"午休"现象,但是不同性别Pn、Tr和Gs的高峰和低谷出现的时间和大小不同。青杨雌雄植株的WUEi从8:00开始降低到一个最小值后升高,且雌株在16:00出现1个峰值;雄株叶片的Pn、Gs、Tr、WUEi、Fm、Fo、Fm'、Fo'、Fv'/Fm'、ETR显著大于雌株(P<0.05),而NPQ则是雌株显著大于(P<0.05)雄株,Ci、Ls、Fv/Fm、Fv/Fo、ФPSⅡ、qP性别间差异则不显著(P>0.05);相关性分析结果表明,对Pn影响最大的因子是Gs,其次是Ca、PAR、RH、Ta和VPD。对Tr影响最大的因子是Gs,其次是Ca、RH、PAR、Ta和VPD。可见,与雌株相比,青杨雄株的捕获光能效率、电子传递速率、光合效率以及水分利用效率较高,雄株对逆境适应能力更强。

A field research was conducted on the characteristics of chlorophyll fluorescent parameters and daily dynamics of photosynthesis in dioecious Populus cathayana cutting seedlings. The results showed as follows： The curves of diurnal variation in Pn, Tr and Gs of dioecious cutting seedlings leaves had two peaks, and a significant midday depression phenomenon, although there were differences in the time and the value of the peaks and valleys occurred in terms of Pn, Tr and Gs. WUEi decreased from morning to noon, reached the lowest value and then increase, he female individuals had the highest value of WUEi at 16：00; The photosynthetic indexes of male individuals such as Pn, Gs, Tr, WUEi, Fm, Fo, Fm′, Fo′, Fv′/Fm′ and ETR were significantly higher than those of female individuals （P〈0.05）, but significantly lower NPQ than female individuals. Moreover, the gender-pecific differences of male and female cutting seedlings in Ci, Ls, Fv/Fm, Fv/Fo, ФPSⅡ and qP were not significant （P〉 0.05）; Correlation analyses showed that the parameters affecting Pn could be ranked, from the highest to the lowest, as Gs〉Ca〉RH〉VPD〉Ta〉PAR, and the factors Tr could be ranked as Gs〉Ca〉RH〉VPD〉PAR〉Ta. The effects of climate factors on photosynthesis rate, transpiration rate of P.cathayana were obvious. Comparing with the female, the male had higher efficiency of light energy captured, electron transport rate, photosynthetic efficiency and water use efficiency, and thus, had greater resistance against adversity.