干旱-复水对旱柳生长与光合生理特性的影响

Effects of Drought and Rehydration on the Growth and Photosynthetic Physiological Characteristics of Salix matsudana

采用盆栽控水的方式研究了干旱复水条件下旱柳的生长和光合生理响应,以明确旱柳对干旱胁迫的应对策略,揭示旱柳对干旱-复水的适应性机制。结果表明:干旱胁迫导致旱柳叶片脱落,枝条和根系的生长被显著抑制,叶片气体交换参数和实际光化学效率随干旱胁迫程度的加剧显著降低,重度干旱处理12天后,净光合速率(P n)、蒸腾速率(T r)、气孔导度(G s)、胞间CO 2浓度(C i)分别较对照显著下降了78.45%、85.04%、90.08%、16.13%,实际光化学效率(ΦPSⅡ)较对照显著下降了22.90%。干旱胁迫下,旱柳表现出等水植物的特点,碳饥饿是旱柳旱害的主要诱因。复水后,旱柳生长的恢复受干旱胁迫强度的影响。重度干旱复水后叶片数量呈爆发式增加,而根系生长未能恢复到对照水平。气孔导度、蒸腾速率和胞间CO 2浓度的恢复受干旱胁迫强度的负调控,中度干旱处理在复水后8天恢复,而重度干旱处理的恢复滞后于复水后12天。于其他3项参数不同,各处理的净光合速率在复水后4天即可恢复至对照水平。旱后复水旱柳叶片光合速率的恢复并不依赖于气孔限制的解除,而决定于实际光化学效率等非气孔限制因子的生理补偿。

The growth and photosynthetic physiological responses of Salix matsudana under drought-rewatering conditions were studied by potted water control method to determine the replying strategies of Salix matsudana to drought stress,and to reveal the adaptability mechanism of Salix matsudana to drought-rehydration.The results showed that the drought stress caused the leaves of Salix matsudana to fall off,the growth of shoots and roots was significantly inhibited,and the gas exchange parameters and actual photochemical efficiency of leaves decreased significantly with the increase of drought stress.After 12 days of severe drought treatment,the net photosynthetic rate(P n),The transpiration rate(T r),stomatal conductance(G s),and intercellular CO 2 concentration(C i)were significantly lower than the control by 78.45%,85.04%,90.08%,and 16.13%,respectively.The actual photochemical efficiency(ΦPSII)was significantly lower than the control by 22.90%.Under drought stress,the Salix matsudanas showed the characteristics of water plants,and carbon starvation was the main cause of drought damage.After rewatering,the restoration of Salix matsudana growth was affected by the intensity of drought stress.After severe drought,the number of leaves increased explosively,while root growth failed to return to the control level.The recovery of stomatal conductance,transpiration rate and intercellular CO 2 concentration was negatively regulated by drought stress intensity.The moderate drought treatment recovered 8 days after rehydration,while the recovery of severe drought treatment lags 12 days after rehydration.Different from the other three parameters,the net photosynthetic rate of each treatment can be restored to the control level 4 days after rehydration.The recovery of photosynthesis rate in the leaves of Rehydra edulis after drought does not depend on the release of stomatal limitation,but is determined by the physiological compensation of non-stomatal limiting factors such as actual photochemical efficiency.