Abstract: In order to investigate the photosynthetic characteristics and antioxidant enzymes of Vicia faba L. responded to Cs+ stress, this study sprayed the potted planting V. faba with 0~200 mg/L concentrations of Cs+ solution simulating soil contamination by 137Cs subsidence with rain; and measured the changes in photosynthetic characteristics and antioxidant enzyme activities of V. faba seedlings. The results showed that the chlorophyll content of leaves increased firstly then decreased with the increasing of Cs+ concentration. The photosynthetic rate (Pn) increased after low concentration (25 mg/L) Cs+ treatment, whereas decreased slightly with high concentration (200 mg/L) treatment. Furthermore, the transpiration rate (E), stomatal conductance (Gs) and intercellular CO2 concentration (Ci) were significantly increased, but the conversion efficiency of primary light energy (Fv/Fm), quantum yield of PSⅡ electron transport (ΦPS Ⅱ), photochemical quenching (qP) and photosynthetic electronic transport rate (ETR) did not change significantly. However, non-photochemical quenching (qNP) increased significantly under the treatments of 50 mg/L and 200 mg/L. Thus, the non-photochemical dissipation of V. faba was enhanced. The activities of peroxidase (POD) and ascorbic acid peroxidase (APX) decreased significantly under different treatments. The responses of POD and APX to Cs+ stress were stronger than that of superoxide dismutase (SOD). Correlation analysis indicated that Pn, POD and APX activity of V. faba were negatively correlated with the concentration of Cs+ in vivo. The results indicated that V. faba seedlings had strong tolerance to Cs+ stress and a better Cs+ enrichment capacity, mainly storing up in root and with strengthened security. Thus, V. faba seedlings had greater potential in application for repairing soil Cs+ contamination.

Key words: Cs+, soil contamination, photosynthetic characteristics, antioxidant enzyme

摘要： 为研究蚕豆的光合特性及抗氧化酶在铯(Cs+)胁迫下的响应特征，用浓度为0~200 mg/L Cs+溶液浇灌盆栽蚕豆，模拟137Cs随雨水沉降造成的土壤放射性污染，测定不同浓度Cs+溶液浇灌下蚕豆幼苗的光合特性及抗氧化酶活性等的变化。结果显示，蚕豆叶片叶绿素含量随Cs+浓度的增加呈现先增加后下降的趋势，低浓度Cs+（25 mg/L）处理净光合速率（Pn）有所增加，高浓度（200 mg/L）处理Pn略有下降；蒸腾速率（E）、气孔导度(Gs)、胞间CO2浓度（Ci）在一定程度上显著增加；蚕豆叶片的原初光能转化效率（Fv/Fm）、PSⅡ实际光化学效率(ΦPSⅡ)、光化学淬灭系数（qP）、电子传递速率（ETR）等无显著性变化，非光化学淬灭系数(qNP) 在50 mg/L和200 mg/L处理下显著升高，非光化学耗散增强；过氧化物酶（peroxidase，POD）和抗坏血酸（ascorbate peroxidase，APX）活性显著降低，POD和APX对Cs+胁迫的响应要强于超氧化物歧化酶（superoxide dismutase，SOD）；相关性分析表明，蚕豆的Pn和POD、APX活性与其体内Cs+富集量呈一定的负相关关系。结果表明蚕豆对Cs+胁迫的耐受性强，有较强的Cs+富集能力，且主要蓄积在根中，安全性增强，在土壤铯污染修复中具有较大的应用潜力。

关键词: 铯, 土壤污染, 光合特性, 抗氧化酶