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草业学报 ›› 2018, Vol. 27 ›› Issue (10): 23-34.DOI: 10.11686/cyxb2017463

• 研究论文 • 上一篇    下一篇

镉对梭鱼草叶片保护酶活性、光合及荧光特性的影响

辛建攀, 李文明, 祁茜, 田如男*   

  1. 南京林业大学风景园林学院,江苏 南京 210037
  • 收稿日期:2017-11-01 修回日期:2017-12-04 出版日期:2018-10-20 发布日期:2018-10-20
  • 通讯作者: E-mail: beike0607@aliyun.com
  • 作者简介:辛建攀(1985-),男,河北邯郸人,在读博士。E-mail: jianpanxin@yeah.net
  • 基金资助:
    国家自然科学基金项目(31670698),江苏省“六大人才高峰”项目(2014-NY-014)和江苏高校品牌专业建设工程项目(PPZY2015A063)资助

Effects of Cd on antixoidant enzyme activities, and leaf photosynthetic and fluorescence characteristics in Pontederia cordata

XIN Jian-pan, LI Wen-ming, QI Xi, TIAN Ru-nan*   

  1. Colledge of Landscape Architecture, Nanjing Forestry University, Nanjing 210037, China
  • Received:2017-11-01 Revised:2017-12-04 Online:2018-10-20 Published:2018-10-20

摘要: 为探究梭鱼草的耐镉能力和生理机制,以溶液培养法研究了不同浓度镉胁迫下梭鱼草叶片保护酶活性、叶绿素含量、光合气体交换参数及叶绿素荧光参数的变化。结果表明:梭鱼草叶片细胞膜透性随镉浓度的增加和胁迫时间的延长而增加。各处理组中叶片过氧化氢酶(CAT)活性基本处于相对稳定水平,超氧化物歧化酶(SOD)随镉浓度的增大呈下降趋势,过氧化物酶(POD)随镉浓度的增大和胁迫时间的延长呈先上升后下降的趋势。叶片叶绿素a(Chla)、叶绿素b(Chlb)含量、叶绿素总含量(ChlT)及叶绿素a/b(Chla/b)比值随着镉浓度的增加和胁迫时间的延长呈下降趋势,其中叶绿素a(Chla)较为敏感,在较短时间内即发生分解,是导致ChlT含量减少的主要原因。叶片净光合速率(Pn)、蒸腾速率(E)、气孔导度(Gs)及胞间CO2浓度(Ci)均随镉浓度的增加和胁迫时间的延长呈下降趋势,饱和蒸气压亏缺(VPD)呈上升趋势,其中Gs降低是导致叶片Pn下降的主要因素。较高浓度(25,75 mg·L-1)镉胁迫下梭鱼草叶片光合作用发生光抑制,使电子传递受阻,导致光系统Ⅱ(PSⅡ)反应中心的光能转化和利用效率下降,但其可通过增加非光化学途径的热耗散和激活未活化的反应中心来适应镉胁迫。

关键词: 梭鱼草, 镉胁迫, 保护酶活性, 光合色素, 光合特性, 叶绿素荧光特性

Abstract: Plants of Pontederia cordata were cultivated in 1/2 strength Hoagland’s nutrient solution containing cadmium at concentrations of 0, 5, 25 or 75 mg·L-1, to research cadmium tolerance and its physiological mechanisms. Changes with Cd exposure in antioxidant enzyme activities, leaf chlorophyll contents, photosynthetic gas exchange and chlorophyll fluorescence parameters in P. cordata leaves were measured. It was found that plasma membrane permeability tended to increase with cadmium concentration and with exposure time. Changes in activities of superoxide dismutase (SOD), peroxidase (POD) and hydrogen peroxidase (CAT) differed. CAT activity was seldom influenced by Cd, whereas activities of SOD and POD were increased by Cd. Leaves showed an obvious decrease in chlorophyll a (Chla), chlorophyll b (Chlb), and total chlorophyll (ChlT) contents and in chlorophyll a/b (Chla/b) ratio with Cd exposure, and this effect was also more marked with increasing Cd concentration and exposure time. Chla was more sensitive to Cd, and Chla reduction was primarily responsible for the reduction in the ChlT content and for the reduced Chla/b ratio. A Cd-induced decrease in net photosynthetic rate (Pn) of P. cordata leaves was observed and was associated with a decline in stomatal conductance (Gs). Linked to this effect, transpiration rate (E), and intercellular CO2 concentration (Ci) of leaves were also decreased by increased Cd concentration and exposure time, while vapor pressure deficit (VPD) was increased. Also, higher Cd concentrations (25, 75 mg·L-1) resulted in photoinhibition, decreasing the photosynthetic electron transport system activity, and thus leading to a decline in energy conversion and utilization efficiency of photosystemⅡ (PSⅡ). However, P. cordata can adapt to Cd exposure by enhancing thermal dissipation and activating non-activated PSⅡ reaction centers.

Key words: Pontederia cordata, Cd stress, antioxidant enzyme activities, chlorophyll contents, photosynthetic characteristics, chlorophyll fluorescence characteristics