锶胁迫对垂柳光合生理的影响

Effects of Sr Stress on Photosynthetic Physiology of Salix babylonica

该文主要探讨水培条件下,不同浓度锶胁迫(^(88)Sr^(2+),0、1、3、5、8 mmol/L)对垂柳(Salix babylonica)光合作用能力的影响,进而为利用木本植物生态治理锶污染奠定研究基础。试验结果表明:随着^(88)Sr^(2+)浓度的升高,荧光参数PSII的实际光能转换效率(Y(Ⅱ))、最大光能转换效率(F_v/F_m)、光化学淬灭系数(qP)、均随着浓度的升高而呈现出先升高后而下降,在1 mmol/L时达到最大;非光化学猝灭系数(NPQ)在8 mmol/L处理时显著升高,表明高浓度^(88)Sr^(2+)处理,叶片PSII光能转换效率虽然显著下降,但通过增加热耗散对光合器官进行一定程度保护;气体交换参数蒸腾速率(E)、气孔导度(Gs)和光合速率(A)均随着^(88)Sr^(2+)的升高也呈现出先升后降的趋势,均在1 mmol/L达到最大;而胞间CO_2(Ci)浓度则逐渐升高,说明影响光合速率的主要因素是非气孔因素占主导;此外,叶片叶绿素a、b和a/b也呈现出先升后降的趋势,且在1 mmol/L时叶片叶绿素含量最高。研究结果揭示低浓度^(88)Sr^(2+)胁迫处理能够通过增强垂柳叶片光能利用、气体交换能力和叶绿素合成来促进其光合作用能力,但高浓度的胁迫会对植物的光合能力带来明显的损伤进而影响其正常的生长发育。

A hydroponic experiment was conducted to investigate the effect of gradient concentrations of ^88Sr^2＋（0,1,3,5,8 mmol/L） stress on the photosynthesis ability of young Salix babylonica. The results showed the actual optical conversion efficiency（Y（Ⅱ））,the maximum energy conversion efficiency（Fv/Fm）,photochemical quenching coefficient（qP）,the maximum fluorescence yield（Fm）reached the maximum at 1 mmol/L -（88）Sr^2＋,and then decreased gradually. However,NPQ increased significantly at 8 mmol/L^88Sr^2＋indicating the protection photosynthetic organs by the growth of heat dissipation. In addition,compared to the control group,the gas exchange parameters transpiration rate（E）,stomatal conductance（Gs）,photosynthetic rate（A） increased and reached the maximum at 1 mmol/L ^88Sr^2＋,and then decreased. Moreover,the gradual increasing intercellular CO2 concentration（Ci） suggested the nonstomatal factors were the major causes of the decline in photosynthesis. On the other hand,the contents of chlorophyll a,chlorophyll b and a/b increased first and decreased later with the maximum of chlorophyll content at 1 mmol/L ^88Sr^2＋. The results revealed low concentration of ^88Sr^2＋would be helpful to the photosynthesis of willow. In contrast,the relative high concentration of ^88Sr^2＋ would do harmful to the growth of willow.