短暂低温对佛手光合生理的影响

Effects of short term chilling stress on the photosynthetic physiology of fingered citrons(Citrus medica var.sarcodactylis Swingle)

佛手(Citrus medicavar.sarcodactylisSwingle)是一种对冷胁迫较为敏感的观果植物,在生产中普遍存在着冷害影响植物生长的现象。通过模拟浙中地区冬季设施种植中常见的短暂低温弱光条件,研究了佛手叶片的光合生理变化。研究表明,15℃低温即显著降低佛手光合速率、气孔导度,显著提高胞间CO2浓度;引起Fv/Fm显著性下降及初始荧光Fo显著上升的拐点温度为10℃,但延长处理时间至72h情况下,15℃亦显著降低Fv/Fm;低温处理还降低佛手光合羧化效率、最大光合速率,并导致光抑制现象发生时对应光强降低;低温条件下佛手叶片质膜透性及MDA含量高于对照,SOD、POD、CAT等抗氧化酶的活性则呈下降趋势;由此可见,短暂低温弱光胁迫首先是降低核酮糖1,5-二磷酸羧化酶(Rubisco)等碳固定关键酶活性,引起氧自由基积聚,进而引发光抑制及光合速率的下降。

Fingered Citrons （Citrus medica vat. sarcodactylis Swingle） is a chilling-sensitive omament fruit plant. The C stress greatly affects its growth and yield. In this study, we studied the changes of photosynthetic physiology under a simulated chilling condition which happens frequently in mid-Zhejiang area. The resuhs showed temperature below 15℃ significantly decreased the net photosynthetic rate, stomatal conductance and increased the intercellular CO2 concentrations. The 10℃ was the inflection point where the Fv/Fm began to decline rapidly and Fo began to increase. However, the 15℃ decreased the Fv/Fm significantly if the treatment length was postponed to 72h. Chilling stress also led to declines of carboxylation efficiency, the maximum photosynthetic rate, and the PFD when the photoinhibition was observed. In contrast to the control, the chilling treatment generally led to a rise of relative electric conductivity （REC） in leaves and declines of SOD, POD and CAT activities. In brief, short term chilling stress primarily weakened the activity of key enzyme in photosynthetic carbon fixation, such as Rubisco, caused an accumulation of reactive oxygen species, and then led to photoinhibition and a decline in photosynthetic rate.