| 摘要: |
| 【目的】阐明桤木（Alnus cremastogyne）幼苗生长及光合生理对镉（Cd）胁迫的响应机制。【方法】采用盆栽试验，设置0，12.5，25.0，50.0，100.0 mg/kg Cd处理，分别用CK、T1、T2、T3、T4表示，测定不同含量Cd处理桤木幼苗生长（株高和地径净生长量、生物量）、叶片光合色素（叶绿素a（Chl a）、叶绿素b（Chl b）、类胡萝卜素（Car））含量以及气体交换参数（气孔导度（Gs）、净光合速率（Pn）、蒸腾速率（Tr）、胞间CO2浓度（Ci）），同时测定了不同含量Cd对桤木幼苗叶片光合 光响应特征曲线及其参数（表观量子效率（AQY）、最大净光合速率（Pn,max）、光饱和点（LSP）、暗呼吸速率（Rd）、光补偿点（LCP））和叶绿素荧光参数（PSⅡ潜在活性（Fv/F0）、PSⅡ最大光化学量子效率（Fv/Fm）、PSⅡ有效光化学量子效率（Fv＇/Fm＇）、PSⅡ实际光化学量子产量（ΦPSⅡ）、表观光合电子传递速率（ETR）、光化学淬灭系数（qP）和非光化学淬灭系数（NPQ））的影响。【结果】不同含量Cd处理桤木幼苗生长指标有明显差异。随着Cd含量的升高，桤木幼苗的株高净生长量、地径净生长量和生物量均呈下降趋势。不同含量Cd对桤木幼苗叶片光合色素含量、气体交换参数、光合 光响应特征曲线及其参数和叶绿素荧光参数均有明显影响。随着Cd胁迫程度的加剧，桤木幼苗叶片Chl a、Chl b、Car和叶绿素总含量（Chl（a+b））总体均呈下降趋势，Chl a/b无显著变化；Gs、Pn以及Tr总体降低，而Ci总体升高。当光合有效辐射（PAR）<200 μmol/（m2·s）时，随着PAR的增加，桤木幼苗的叶片Pn先迅速上升；之后随着PAR继续增加，Pn上升的速率减缓；当PAR≥800 μmol/（m2·s）之后，Pn趋于稳定。不同含量Cd处理桤木幼苗叶片的光合 光响应曲线差异明显，在同一PAR下，各处理Pn总体表现为CK>T1>T2>T3>T4。随着Cd胁迫程度的加剧，桤木幼苗叶片AQY、Pn,max、LSP和Rd总体降低，LCP总体升高；Fv/F0、Fv/Fm、Fv＇/Fm＇、ETR和ΦPSⅡ以及qP总体均下降，但NPQ总体呈上升趋势。【结论】当土壤Cd含量较高（25.0~100.0 mg/kg）时，桤木幼苗生长和叶片及光合生理特性受到了明显抑制，表明桤木幼苗对Cd胁迫的耐受性较低，因此将桤木不要种植在Cd污染严重的地区。但在Cd污染程度较轻（Cd含量≤12.5 mg/kg）的地区，桤木能够正常生长，可用于轻度Cd污染土壤修复。 |
| 关键词: 桤木 镉胁迫 光合生理 叶绿素荧光 |
| DOI：10.13207/j.cnki.jnwafu.2025.07.008 |
| 分类号: |
| 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 growth and photosynthetic physiology of Alnus cremastogyne seedlings to cadmium stress |
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DENG Wen1, HU Hongling1, ZHANG Chenghao1, LI Chuang1, GUAN Peng1, CHEN Gang1, CHEN Hong2
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1.College of Forestry,Sichuan Agricultural University,Chengdu,Sichuan 611130,China;2.College of Agricultural Science,Xichang University,Xichang,Sichuan 615000,China
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| Abstract: |
| 【Objective】This research aimed to elucidate the growth and physiological mechanisms of photosynthesis of Alnus cremastogyne seedlings in response to Cd-stress.【Method】Pot trials named CK,T1,T2,T3 and T4 were conducted with 0,12.5,25.0,50.0 and 100.0 mg/kg Cd.The growth (grass height,net diameter and biomass),leaf photosynthetic pigments (chlorophyll a (Chl a),chlorophyll b (Chl b),carotenoids (Car)) and gas exchange parameters (stomatal conductivity (Gs),net photosynthetic rate (Pn),transpiration rate (Tr) and intercellular CO2 concentration (Ci)) of A.cremastogyne seedlings from different treatment groups were assessed.Effects of different Cd concentrations on the characteristic photosynthesis-light response curves and their parameters (apparent quantum efficiency (AQY),maximum net photosynthetic rate (Pn,max),light saturation point (LSP),dark respiration rate (Rd),light compensation point (LCP)) of Alnus cremastogyne seedling leaves and its effects on chlorophyll fluorescence parameters (potential PSⅡ activity (Fv/F0),maximum PSⅡ photochemical efficiency (Fv/Fm),effective photochemical efficiency of PSⅡ (Fv＇/Fm＇),effective photochemical quantum yield of PSⅡ (ΦPSⅡ),electron transfer rate (ETR),photochemical extinction coefficient (qP) and non-photochemical extinction coefficient (NPQ) were assessed.【Result】Significant differences were observed in the growth indices of A.cremastogyne seedlings treated with different levels of Cd.The plant height growth,net soil diameter growth and net biomass growth decreased with the increase of Cd concentration.Different Cd concentrations had significant effects on photosynthetic pigment content,gas exchange parameters,photosynthesis and light characteristic curves and their parameters,and chlorophyll fluorescence parameters in A.cremastogyne seedlings.With increasing Cd stress level,Chl a,Chl b,Car and total chlorophyll (Chl（a+b）) contents of A.cremas togyne seedlings showed a decreasing trend,while no significant change was observed for Chl a/b.Gs,Pn and Tr generally decreased,while Ci increased.When photosynthetically active radiation (PAR) was< 200 μmol/(m2·s),Pn content in A.cremastogyne seedling leaves initially increased rapidly and then slowed as PAR increased,and finally stabilised when PAR was ≥800 μmol/(m2·s).Significant difference was observed in the photosynthesis-light response curves of A.cremastogyne seedling leaves treated with different Cd concentrations.For the same PAR value,the Pn of each treatment ranked as CK>T1>T2>T3>T4.With increasing Cd stress level,AQY,Pn,max,LSP and Rd of A.cremastogyne seedling leaves generally decreased and LCP increased.Fv/F0,Fv/Fm,Fv＇/Fm＇,ETR and ΦPSⅡ as well as qP decreased while NPQ increased.【Conclusion】At high levels of Cd in the soil (25.0-100.0 mg/kg),the growth and physiological properties of leaves and photosynthesis of A.cremastogyne seedlings deteriorated significantly,indicating a low resistance of A.cremastogyne seedlings to Cd stress.Therefore,A.cremastogyne should not be planted in areas with high Cd contamination.However,in sites with low Cd contamination (Cd content≤12.5 mg/kg),A.cremastogyne seedlings can grow normally and be used to reclaim soils with low Cd contamination level. |
| Key words: Alnus cremastogyne cadmium stress photosynthetic physiology chlorophyll fluorescence |
