不同光环境下桢楠幼树叶片叶绿素荧光特性

Chlorophyll Fluorescence Characteristics of Phoebe zhennan Seedlings under Different Light Regimes

对不同光环境下桢楠幼树叶片主要叶绿素荧光参数的日变化进行了测定。结果表明:在全光照(Ⅰ型)和90%光照(Ⅱ型)环境下,F0(最小荧光)、Fm(最大荧光)、F'm(光适应下的最大荧光)、Fv(可变荧光)、Fv/Fm(PSⅡ最大光能转换效率)、Fm/F0(电子传递效率)和Fv/F0(PSⅡ潜在活性),从08:00—18:00均呈现下降的趋势。而在60%～65%光照(Ⅲ型)和50%～55%光照(Ⅳ型)环境下,则呈现先降后升的单谷型,最小值出现在12:00—14:00。在全光照(Ⅰ型)和90%光照(Ⅱ型)环境下,NP,Q(非光化学淬灭系数)日变化则呈现上升的趋势;而在60%～65%光照(Ⅲ型)和50%～55%光照(Ⅳ型)环境下,则呈现先升后降的单峰型,最大值出现在12:00—14:00。在Ⅰ型和Ⅱ型光环境之间,除F0和NP,Q的日均值存在显著差异(P<0.05)外,其他叶绿素荧光参数日均值无显著差异。在Ⅲ型和Ⅳ型光环境之间,各项叶绿素荧光参数日均值均不存在显著差异。但是,Ⅰ型和Ⅱ型光环境下的F0、Fm、F'm、Fv、Fv/Fm、Fm/F0、Fv/F0日均值都分别极显著(P<0.01)低于Ⅲ型和Ⅳ型光环境下的对应值,而Ⅰ型和Ⅱ型光环境下的NP,Q日均值却极显著(P<0.01)高于Ⅲ型和Ⅳ型光环境下的对应值。由此可见,Ⅰ型和Ⅱ型光环境下的桢楠幼树叶片吸收的光能有更大比例用于热耗散而保护自身的光合机构。

A study was performed to determine the daily changes of chlorophyll fluorescence parameters of Phoebe zhennan seedlings under different light regimes. Results show that the minimal fluorescence （ F0 ）, maximal fluorescence （ Fm ） , actual maximal fluorescence （ F＇m ）, variable fluorescence （ Fv ）, optimal/maximal photochemical efficiency of PS 1I （ Fv/Fm ）, electron transfer rate （ Fm/F0 ）, and potential activity of PS II （ Fv/F0 ） showed descending trends under 100% and 90% of light intensity between 8：00 and 18：00. However, these chlorophyll fluorescence parameters showed descending-as- cending trends under 60% -65% and 50% -55% of light intensity between 8：00 and 18：00, and the lowest values occurred between 12：00 and 14：00. The non-photochemical quenching （NP,Q） in 100% and 90% of light intensity showed ascending trends between 8：00 and 18：00. The NPQ in 60% -65% and 50% -55% of light intensity showed ascending-descending trends between 8：00 and 18：00, and the highest values occurred between 12：00 and 14：00. Results also showed that, except the significant differences （at the 0.05 level） in the average values of F0 and Nm, there were no significant differences in other chlorophyll fluorescence parameters between 100% and 90% of light intensity. There were no signifi- cant differences in the average values of all chlorophyll fluorescence parameters between 60% -65% and 50% -55% light intensity. The average values of F0、Fm、F＇m、Fv、Fv/Fm、Fm/F0 and Fv/F0 under 100% and 90% of light intensity, however, were significant （ at the 0.01 level） lower than those under 60% -65% and 50% -55% of light intensity. On the contrary, the averages value of NPQ under 100% and 90% of light intensity were significant （ at the 0.01 level） higher than those under 60% -65% and 50% -55% of light intensity, indicating that higher proportion of light energy absorbed by P. zhennan seedlings under 100% and 90% of light intensity was used for avoiding the destruction of photosynthetic tissue through heat dissipation.