| 摘要: |
| 【目的】研究巨桉幼树对镉胁迫的光合生理响应，为巨桉适宜立地条件的选择提供参考。【方法】以1年生巨桉幼树为试验材料，采用盆栽控制试验，设置CK（0 mg/kg）、T1（12.5 mg/kg）、T2（25 mg/kg）、T3（50 mg/kg）、T4（100 mg/kg）5个镉(Cd)处理水平，每个处理重复3次，将每个处理Cd用量等分为5份，分别于2018年5-9月施入，10月底测定各处理植株的光合色素含量及光合特性、光合 光响应曲线和叶绿素荧光参数。【结果】随着Cd施入水平的升高，巨桉幼树叶片叶绿素a（Chl a）、叶绿素b（Chl b）、总叶绿素Chl（a+b）和类胡萝卜素（Car）含量均呈下降趋势，Chl a/b呈先升后降趋势；净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）逐渐减小，胞间二氧化碳浓度（Ci）逐渐增大；表观量子效率（AQY）、光饱和点（LSP）、最大净光合速率（Pmax）和暗呼吸速率（Rd）均逐渐降低，光补偿点（LCP）则逐渐上升；初始荧光（F0）、最大荧光（Fm）、实际光化学量子产量（ΦPSⅡ）和PSⅡ最大光化学量子产量（Fv/Fm）均逐渐降低，电子传递效率（ETR）先降低后升高，PSⅡ潜在活性（Fv/F0）先升高后降低，而光化学淬灭系数（qP）和非光化学淬灭系数（NPQ）无显著变化；天线热耗散能量（D）和光化学反应耗散能量（P）降低，而非光化学反应耗散能量（Ex）增加。【结论】土壤中较高的镉含量对巨桉幼树的光合生理具有明显抑制作用，应尽量避免在镉污染严重地区发展巨桉人工林，也不宜选择巨桉作为镉富集植物用于污染区的生态修复。但在镉污染程度较轻的地区，如土壤中Cd含量在12.5 mg/kg以下时，种植巨桉还是可行的。 |
| 关键词: 巨桉 镉胁迫 光合生理 光响应 叶绿素荧光 |
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| 基金项目:四川省“十三五”农作物育种攻关项目（2016NZ0098-10） |
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| Response of photosynthetic physiology of Eucalyptus grandis saplings to cadmium stress |
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WEN Jing,HU Hongling,CHEN Hong,et al
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| Abstract: |
| 【Objective】This study analyzed the photosynthetic and physiological responses of Eucalyptus grandis saplings to cadmium stress to provide reference for the selection of suitable site conditions for E.grandis.【Method】One year old E.grandis saplings were selected for potted control experiments with 5 cadmium levels of CK (0 mg/kg),T1 (12.5 mg/kg),T2 (25 mg/kg),T3 (50 mg/kg) and T4 (100 mg/kg).Each treatment had 3 replicates,and cadmium amount was applied equally in each month from May to September 2018.The photosynthetic pigment content,photosynthetic characteristics,photosynthetic light response and chlorophyll fluorescence parameters of treated plants were measured by the end of October.【Result】With the increase of cadmium level,the contents of chlorophyll a (Chl a),chlorophyll b (chl b),Chl (a+b) and carotenoid (car) all decreased,and Chl a/b increased first and then decreased.Net photosynthetic rate (Pn),stomatal conductance (Gs) and transpiration rate (Tr) decreased gradually,while intercellular carbon dioxide concentration (Ci) increased gradually.The apparent quantum efficiency (AQY),light saturation point (LSP),maximum net photosynthetic rate (Pmax) and dark respiration rate (Rd) decreased,while light compensation point (LCP) increased gradually.The initial fluorescence (F0),maximum fluorescence (Fm),actual photochemical quantum yield (ΦPSⅡ) and maximum photochemical quantum yield (Fv/Fm) of PSⅡ decreased.The electron transfer efficiency (ETR) first decreased and then increased,while the potential activity (Fv/F0) of PSⅡ first increased and then decreased.The photochemical quenching coefficient (qP) and non photochemical quenching coefficient (NPQ) did not change significantly.The thermal dissipation energy (D) and photochemical reaction energy (P) decreased,while the dissipated energy of non photochemical reaction (Ex) increased.【Conclusion】High cadmium contents in soil had significant inhibitory effects on the photosynthetic physiology of E. grandis saplings.Therefore,it is necessary to avoid the development of E.grandis plantation in areas with severe cadmium pollution,and it is not suitable to choose E. grandis as cadmium-enriched plant for ecological restoration in cadmium contaminated areas.However,it is feasible to plant E. grandis in areas with less cadmium pollution of below 12.5 mg/kg. |
| Key words: Eucalyptus grandis cadmium stress photosynthetic physiology photosynthetic light response chlorophyll fluorescence |
