钙对镉胁迫下秋茄叶片光合作用及超微结构的影响

Effect of Calcium Supply on Photosynthesis and Ultrastructure of Cells of Kandelia obovata(S.L.)Yong Under Cadmium Stress

研究了不同钙(Ca)浓度下,重金属镉(Cd)对红树植物秋茄[Kandelia obovata(S.L.)Yong)]毒害的差异.采用Hoagland营养液培养,实验采用完全随机设计设9个处理,Cd质量浓度为0,0.5,5.0mg/L 3个水平;Ca质量浓度为0,400,800mg/L 3个水平,研究Ca对重金属Cd胁迫下红树植物秋茄叶片光合指标、叶绿素含量、叶组织的解剖结构、叶绿体等超微结构的影响.研究表明:Cd胁迫显著降低了秋茄叶片的净光合速率、气孔导度、胞间二氧化碳浓度和蒸腾速率,同时叶绿素含量减少,说明Cd对秋茄光合系统有一定的破坏作用,施加一定外源Ca,秋茄叶片光合指标显著上升,同时叶绿素含量增加,说明Ca对秋茄的光合作用有很强的促进效果.施加Ca在一定程度上缓解了秋茄叶片重金属胁迫形成的解剖结构的"旱生化",然而在解剖结构层面上的变化差异不显著.Ca对Cd引起的细胞器结构的损伤破坏有一定的保护和缓解作用,施加外源Ca缓解Cd对细胞器结构破坏的能力也不同,其中适量的Ca对Cd胁迫下的细胞核和叶绿体有很强的修复功能.研究率先揭示了Ca对红树植物耐重金属方面的在光合作用和超微结构方面的表征,以期为揭示红树植物对于重金属的耐性机制及其关键影响因素,并为红树林生态系统重金属污染修复治理提供新的理论依据,为红树林污染的修复提供了一条新思路.

This paper studies the effect of various Ca concentrations on Cd-stressed mangrove species（Kandelia obovata（S.L.）Yong）.9cross-deals were designed completely randomly using Hoagland nutrient solution culture experiment with Cd concentration of 0,0.5,5.0mg/L and Ca concentration of 0,400,800mg/L.Photosynthetic index,chlorophyll content,and leaf tissue anatomy of chloroplast ultrastructure of mangrove plants were observed under these experimental conditions.Results showed that Cd stress significantly reduced the net photosynthetic rate,stomatal conductance,intercellular carbon dioxide concentration and transpiration rate of K.obovata.The chlorophyll content decreased under Cd stress,indicating that Cd ion had some damaging effects on K.obovata photosynthetic system.Addition of exogenous Ca ion to K.obovata significantly increased the leaf photosynthetic indexes and the chlorophyll content indicating that Ca had a strong promoting effect on the photosynthesis of K.obovata.Therefore,Ca could,to some extent,alleviate the ＂dry formation＂ of leaf anatomy of K.obovataunder the heavy metal stress,but differences in the anatomy of the change was not significant.Our data also showed that Ca ions have some protection and relief on Cd-induced cell structure damage.Our results revealed the effect of Ca on heavy metal resistance of mangrove plants in photosynthesis and ultrastructural characterization,and discovered the mechanisms of heavy metal tolerance and key control factors.Our study provides a new theoretical basis for dealing with heavy metal pollution in mangrove ecosystems and a new way to restore polluted mangroves.