水淹和恢复对凤丹光合特性和根系活力的影响

选用3年生油用牡丹凤丹(Paeonia ostii)实生苗为试验材料,以常规供水管理的凤丹苗为对照,测定凤丹光合特性以及根系活力和形态随着水淹和水淹恢复处理时间的变化,探究牡丹的耐湿机制。结果表明:(1)水淹后,凤丹叶片净光合速率、蒸腾速率、气孔导度及根系活力均较对照组显著下降,且下降幅度随着水淹时间的延长而增大;在持续水淹过程中,叶片胞间CO_2浓度则呈先下降后上升的变化趋势;水淹168h时,根系活力在所测定指标中下降幅度最大,仅为对照组的2.34%,此时根系变黑且腐烂,大部分根系脱落。(2)凤丹叶片净光合效率的下降在水淹120h过程中与气孔限制性调节密切相关,而到水淹168h时非气孔限制性成为光合作用的限制因子。(3)水淹72h后进行恢复处理120h后,叶片净光合速率、蒸腾速率、胞间CO_2浓度和根系活力均显著上升;恢复处理168h后,净光合速率和胞间CO_2浓度恢复到正常的生长水平,同时绝大部分根尖呈现白色且发育良好,根系生长向正常的生命状态恢复。研究表明,油用牡丹凤丹对水淹胁迫的应答迅速且灵敏,虽不耐水淹,但恢复能力强,这为其栽培管理以及在相对湿润地区推广种植提供了理论依据。

Effects of Waterlogging and Recovery on the Photosynthetic Characteristics and Root Activity of Paeonia ostii

This essay inquired into the effects of waterlogging and waterlogging recovery treatments on the photosynthetic characteristics and root activity and morphology of the triennial Paeonia ostii. Compared with the control groups (seedlings under normal condition), and thus explored the mechanism of tree peonies in response to waterlogging and recovery. The results revealed that: (1) waterlogging significantly reduced net photosynthetic rate, transpiration rate, stomatal conductance and root activity compared with the control groups. The more waterlogging time, the more reduction. However, the intercellular CO₂ concentration decreased first then increased during the waterlogging. The root activity was the largest decrease in the parameters, only 2.34% of the control groups. The roots are almost black, rotten and even fell off at the waterlogging of 168 h. (2) The decline of photosynthesis was closely related to the regulation of stomatal limitation during the waterlogging of 120 h. However, non stomatal limitation became the limiting factor of photosynthesis at the waterlogging of 168 h. (3) Net photosynthetic rate, transpiration rate, intercellular CO₂ concentration and root activity of waterlogging recovery groups, went through waterlogging of 72 h, all rose significantly after recovery of 120 h. Net photosynthetic rate and intercellular CO₂ concentration of recovered seedlings increased to the level similar to the control by 168 h. Most of the roots appeared white and relatively developed, and the roots recovered to the normal state. It proves that Paeonia ostii is quick and sensitive to waterlogging. Although subject to waterlogging, it has strong ability of recovery. The research provides theoretical basis for cultivation and management of tree peonies.