锶对油菜幼苗叶片光合作用的影响

锶对植物光合作用影响尚未见系统研究报道。通过叶绿素荧光诱导动力学和光合气体交换参数详细研究了不同浓度的锶(1、5、10和20 mmol·L^–1SrCl₂)对油菜(Brassica napus)叶片光合作用的影响。荧光诱导动力学分析结果表明, 光系统II(PSII)的潜在活性(F_v/F_o)、实际光化学效率(Y(II))、表观光合电子传递速率(ETR)和光化学淬灭(qP)在低浓度(1和5 mmol·L^–1)锶处理时显著上升, 在高浓度(10和20 mmol·L^–1)锶处理时显著下降; 初始荧光强度(F_o)和非光化学淬灭(NPQ)在低浓度锶处理时变化不明显, 但在高浓度下显著上升。光合气体交换参数分析结果表明, 叶片的净光合速率(P_n)、蒸腾速率(T_r)在低浓度锶处理时显著上升, 而在高浓度锶处理时显著下降; 气孔导度(G_s)随锶处理浓度的增加一直呈显著下降趋势; 胞间CO₂浓度(C_i)在低浓度锶处理时轻微下降, 高浓度锶处理时显著增加。此外, 叶绿素含量在低浓度锶处理时显著增加, 在高浓度处理时则显著下降。这些结果均表明, 低浓度锶处理可以改善油菜叶片的光合功能, 增加叶片光合效率; 而高浓度锶则会妨碍叶片光合功能, 导致光合效率显著下降。

Effect of Strontium on Photosynthesis of Leaves in Rape Seedlings

Brassica napus (rape) seedlings were treated with different concentrations of strontium (1, 5, 10, 20 mmol·L^–1SrCl₂) for 21 days, and the effect of strontium on the photosynthesis of rape leaves was investigated by chlorophyll fluorescence induction dynamics and photosynthetic gas exchange parameters. Photosystem II potential activity, actual photochemical efficiency, apparent photosynthetic electronic transfer rate, and photochemical quenching increased with low strontium concentration (1, 5 mmol·L^–1) but decreased with high concentration (10, 20 mmol·L^–1). Minimum fluorescence and non-photochemical quenching did not change significantly with low strontium concentration but significantly increased with high concentration. Net photosynthetic rate and transpiration rate of leaves significantly increased with low strontium concentration but decreased with high concentration; stomatal conductance significantly decreased with increasing strontium concentration; intercellular CO₂ concentration increased with high concentration. Chlorophyll content significantly increased with low strontium concentration and decreased with high concentration. Thus, low strontium concentration could improve photosynthetic function of rape seedlings and increase photosynthetic efficiency, but a high concentration can harm the photosynthetic apparatus and significantly inhibit photosynthetic efficiency.