不同干旱处理刺槐、侧柏光合特性与内源脱落酸含量的相关关系

Relationship between photosynthetic characteristics and endogenous abscisic acid content of Robinia pseudoacacia and Platyclus orientalis under different drought treatments

为揭示干旱介导植物光合同化能力的内源脱落酸(ABA)调控机制,以北京地区典型树种刺槐和侧柏为研究对象,探讨土壤快速干旱-复水(T_(1))和慢速干旱-复水(T_(2))处理下,树木碳同化与ABA器官分配模式间相关关系。结果表明:(1)刺槐与侧柏在T_(1)和T_(2)干旱处理阶段的净光合速率(P_(n))、气孔导度(G_(s))、蒸腾速率(Tr)均随土壤体积含水量(SWC)下降显著降低(P<0.05)。T_(1)两树种P_(n)降幅(99.18%和57.30%)大于T_(2)(91.97%和36.69%),且T_(1)、T_(2)刺槐P_(n)、G_(s)降幅均大于侧柏。T_(1)和T_(2)旱后复水阶段,T_(1)两树种P_(n)、G_(s)恢复程度大于T_(2),刺槐光合能力恢复至胁迫处理前水平,而侧柏仅部分恢复。(2)T_(1)和T_(2)两树种叶片、小枝、粗根、细根ABA均随SWC下降显著上升(P<0.05),且T_(2)两树种全株ABA上升幅度(21.21%和26.01%)均大于T_(1)(13.71%和8.91%)。T_(1)和T_(2)两树种粗根在旱后复水阶段ABA显著低于干旱阶段,其它器官ABA均维持干旱阶段水平。(3)探究两树种光合特性与ABA相关关系随土壤水分变化的规律发现,T_(1)和T_(2)处理下两树种光合参数与ABA含量呈显著负相关(P<0.05)。SWC下降速度越慢,两树种光合参数与器官ABA协同变化程度越高,且刺槐光合、ABA两者相关系数高于侧柏。综上所述,光合参数、器官ABA含量变幅及其二者相互关系程度均显著受到土壤干旱节律的影响作用,且存在种间特异性。研究旨在揭示植物应对不同干旱胁迫的碳同化与内源激素调控响应机制,为区域城市园林耐旱林木的选培与管理提供理论参考。

This paper aims to reveal the endogenous abscisic acid(ABA)regulatory mechanism of drought mediated plant photosynthetic capacity,the typical tree species of Robinia pseudoacacia and Platycladus orientalis in Beijing were used to explore the relationship between carbon assimilation and organ ABA allocation modet of young trees under rapid drought⁃rehydration(T_(1))and slow drought⁃rehydration(T_(2)).The results showed that:(1)the net photosynthetic rates(P_(n)),stomatal conductances(G_(s)),and transpiration rates(Tr)of R.pseudoacacia and P.orientalis decreased significantly with the decrease of soil volume water content(SWC)during the T_(1)and T_(2)drought treatment stages(P<0.05).The decrease amplitudes of P_(n)of two tree species in T_(1)(99.18%and 57.30%)were greater than those in T_(2)(91.97%and 36.69%).The decrease in P_(n)and G_(s)of R.pseudoacacia T_(1)and T_(2)were greater than those of P.orientalis.At the stage of post⁃drought rehydration in T_(1)and T_(2),the recovery degrees of P_(n)and G_(s)of two tree species in T_(1)were higher than that in T_(2).The photosynthetic capacities of R.pseudoacacia recovered to the level before water stress treatments of T_(1)and T_(2),while these of P.orientalis only partially recovered.(2)The ABA content in leaves,twigs,coarse and fine roots of two tree species increased significantly increased with the decrease of SWC(P<0.05).The increase amplitudes of ABA at the whole plant level of two tree species T_(2)(21.21%and 26.01%)were higher than those of T_(1)(13.71%and 8.91%).The coarse roots of T_(1)and T_(2)tree species showed significantly lower ABA levels in the rehydration stage after drought compared to the drought stage,while ABA levels in other organs remained at the drought stage level.(3)By exploring the relationship between photosynthetic characteristics and ABA of Two tree species and discovering the regularity of changes in soil moisture,significantly negative correlations were found between photosynthetic parameters and ABA content of two tree species in T_(1)and T_(2)(P<0.05).The slower the decline rate of SWC,the higher the degree of synergistic changes between photosynthetic parameters and organ ABA of the two tree species.And the correlation coefficient between photosynthesis and ABA of R.pseudoacacia is higher than that of P.orientalis.In conclusion,photosynthetic parametersthe,ABA and their relationship in the organs of the two tree species were significantly affected by the soil drought rhythm.This study can reveal the carbon assimilation and endogenous hormone regulation response mechanisms of plants in response to different drought stresses,providing theoretical reference for the selection,cultivation,and management of drought tolerant trees in regional urban landscaping.