不同光强对越南抱茎茶光合及荧光特性日变化的影响

为研究不同光强对越南抱茎茶光合作用机理的影响,设置3种处理方式,即全光照(L1)、光强度45%(L2)、光强度15%(L3),分别在遮阴3个月后测定其光合荧光参数的变化。结果表明,不同光强处理下,净光合速率均呈单峰曲线,峰值出现在11:00左右;光合速率下降主要是气孔限制因素引起的;叶绿素荧光参数表明,强光条件下电子传递受阻,热耗散增加,PSII反应中心受到破坏,从而降低了茶花的光合效率;过度遮阴条件下受到光抑制,从而导致光合机构损伤;45%光照条件下光合效率较高。相关性分析表明,净光合速率(Pn)与空气温度(Ta)、相对湿度(RH)、气孔导度(Gs)、蒸腾速率(Tr)、水分利用效率(WUE)、表观电子传递速率(ETR)呈极显著相关,与RH呈极显著负相关,与胞间CO2浓度(Ci)呈显著负相关。影响越南抱茎茶净光合速率的主要环境因子是空气温度和相对湿度。

Diurnal Changes of Photosynthesis and Fluorescence Parameters in Camellia amplexicaulis under Different Light Intensities

In order to study the effect of different light intensities on the photosynthesis mechanism of Camellia amplexicaulis, we detected the diurnal changes of chlorophyll fluorescence parameters of shade in 3 months respectively. The results showed that under different light intensity treatments, the net photosynthetic rate presented a single-peak curve with the peak at around 11:00am. The decrease of photosynthetic rate was mainly caused by stomatal limitation factor. The chlorophyll fluorescence parameters indicated that electron transfer was blocked, the heat dissipation increased, the PSII reaction center was destroyed under strong light conditions, which reduce the photosynthetic efficiency of C. amplexicaulis; under excessive shade condition, photoinhibition of C. amplexicaulis resulted in damage of photosynthetic apparatus; the photosynthetic efficiency was higher under 45% illumination. Correlation analysis showed that Pn was significantly correlated with Ta, RH, Gs, Tr, WUE and ETR, and was significantly negatively correlated with RH and negatively correlated with Ci. The main environmental factors affecting the net photosynthetic rate of C. amplexicaulis were the temperature and relative humidity of air.