乳源木莲幼树叶片叶绿素荧光特性

Chlorophyll Fluorescence Characteristic of Seedlings of MangLietia yuyuanensis

对不同季节乳源木莲(MangLietia yuyuanensis)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,乳源木莲幼树叶绿素荧光参数在春季和秋季的日变化幅度较小。在夏季08:00—18:00,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/Fo(电子传递效率)、Fv/Fo(PSⅡ潜在活性)呈现先降后升的规律,最低值出现在14:00;而NP,Q(非光化学猝灭系数)呈现先升后降的规律,最高值出现在12:00。Fm、F'm、Fv、Fv/Fm、Fm/Fo、Fv/Fo在冬季1 d中的变化则呈现先升后降的规律,最高值出现在14:00左右;而NP,Q在1 d中的变化情况则正好相反,最低值出现在14:00。春秋季节的Fv/Fm、Fm/Fo和Fv/Fo显著高于冬夏季节,表明乳源木莲幼树春秋季节叶片PSⅡ反应中心电子传递效率和潜在活性显著高于冬夏季节;乳源木莲幼树冬季和夏季的NP,Q参数显著高于春秋季节,表明乳源木莲幼树在冬季和夏季吸收的光能有较大比例用于耗散而保护自身的光合机构。NP,Q在春、夏和秋季与其大气相对湿度呈显著负相关,与气温和光照呈显著正相关,而在冬季则与气温呈显著负相关;夏季的Fm/Fo、Fv/Fo、Fv/Fm与其气温和光照呈显著负相关,与大气相对湿度呈显著正相关。

The diurnal changes of chlorophyll fluorescence parameters of MangLietia yuyuanensis in different seasons were inves- tigated. The results show that the daily fluctuation of chlorophyll fluorescence parameter is small in spring and autumn. The values of Fro（ maximal fluorescence）, F＇m（ actual maximal luoreseeuce）, Fv（ variable fluorescence）, Fv/Fm（ optimal/ maximal photochemical efficiency of PS 1I ）, Fm/Fo（ electron transfer rate） and Fv/Fo（ potential activity of PS II ） show a descending-ascending trend from 8：00 to 18：00 in summer obviously, and the lowest value is at 14：00. But the value of Np,Q（ non-photochemical quenching） from 8：00 to 18：00 in summer obviously presents an ascending-descending trend and the highest value is at 12：00. The daily changes of Fm, F＇m, Fv, Fv/Fm, Fm/Fn and Fv/Fo in winter obviously show a descending-ascending trend, and the highest value is at 14：00. The daily change trend of Np,Q in winter, however, is con- trary to those mentioned above, and the lowest value is at 14：00. The values of Fv/Fm, Fm/Fo and FJFo in spring and autumn are obviously higher than those in summer and winter. Therefore, the electron transfer rate and potential activity of PS 1I in.spring and autum are higher. On the contrary, the value of Np,Q in winter and summer is obviously higher than those in spring and autumn, indicating that higher proportion of light energy absorbed in winter and summer are used for avoi- ding the destruction of photosynthetic tissue through hot dissipation. In spring, summer and autumn, the closely positive and negative correlations are between the value of Np.Q and the value of illumination and air moisture, respectively. In summer, there is a closely negative correlation between the values of Fm/Fo, Fv/Fo, F/Fm and the value of air temperature and illumination, respectively. However, the correlation between the values of Fm/Fo, Fv/Fo, Fv/Fm and the value of air moisture is distinctly positive in summer season.