金花茶幼苗光合生理生态特性研究

采用Li-6400便携式光合作用系统对金花茶盆栽幼苗光合生理特性进行研究。结果表明:1)在不遮阴的条件下,幼苗夏季光合作用有午休现象,最高峰出现在08:00,其净光合速率为3.38μmol/(m2·s);2)光饱和点和光补偿点都较低,分别为476.46和6.13μmol/(m2·s),是一种典型的阴生植物;3)在温度为30℃,光照强度为1000μmol/(m2·s),湿度为50%～60%的条件下,光合能力为12.58～13.50μmol/(m2·s),CO2浓度在25～1000μmol/mol的范围内,其净光合速率随浓度升高而显著上升,CO2饱和点约为1500.00μmol/mol,CO2补偿点为99.48μmol/mol,最大羧化效率为0.0118;4)幼苗喜热,在35℃下净光合速率最高,对低温有一定的适应能力,但不适应40℃的高温条件。5)幼苗不耐干旱,即使轻度水分亏缺也会抑制其光合作用。

Photosynthetic ecophysiological characteristics of Camellia nitidissima seedlings

The photosynthetic physiological characteristics of pot.cultured Camellia nitidissima seedlings were studied with a Li-6400 (LI-COR.Lincoln,Nebraska,USA) portable photosynthesis system.The resuits show that under open conditions without shade,the diurnal changes in the photosynthetic rate (P_n) showed a curve with two peaks and a clear phenomenon of midday depression in photosynthesis.The maximum photosynthetic rate (3.38 μmol/ (m~2·s) appeared at 8:00 AM during the summer.The light saturation (LSP) and light compensation points (LCP) were 476.46 μmol/ (m~2·s) and 6.13 μmol/ (m~2·s) ,respectively.They were very low,indicating that these seedlings required shade condition.Under control condition (temperature 30℃,light 1000 μmol/ (m~2·s) and humidity 50%-60%) ,the photosynthetic capacity was 12.58-13.50 μmol/ (m~2·s) and the photosynthetic rate increased linearly when the concentration of CO_2 increased from 25μmol/mol to 1000μmol/mol.The CO_2 saturation point (CSP) was 1500.00μmol/mol,the compensation point (Г) 99.48 μmol/mol and the maximum carboxylation rate (CE) 0.0118.The seedlings tended to require heat,their photosynthetic rate reached its highest value at 35℃ and had a certain capacity to adapt to low-temperatures.but could not tolerate 40℃.The seedlings were sensitive to drought stress and even a slight water deficit could depress their photosynthesis.