紫花苜蓿光合特性及抗氧化物质对冷适应的响应

Photosynthetic characteristics and response of antioxidant to cold adaptation of alfalfa

摘要:

【目的】探究紫花苜蓿在冷适应过程中光合特性指标和抗氧化物质含量的变化。【方法】将 10 个紫花苜蓿品种的 4 周龄幼苗进行 4 ℃冷适应处理，分别在第 0、7、14 天测定其叶绿素含量、渗透压、相对电导率、光合特性指标、活性氧物质和抗氧化物质含量。【结果】在冷适应初期（0~7 d），细胞膜受到损伤，造成离子泄露，叶片相对电导率升高，但随着冷适应过程的持续（7~14 d），离子泄露量减少，相对电导率降低，植株的抗寒性初步形成；冷适应造成叶绿素 a、b 含量、净光合速率、PSⅡ实际光化学效率及 PSⅡ最大光化学效率降低。【结论】紫花苜蓿幼苗在冷适应过程中，其渗透压、抗坏血酸、氧化型谷胱甘肽和还原型谷胱甘肽含量持续升高，幼苗通过提高细胞液的渗透压，增加细胞液浓度，增强细胞的渗透调节能力，同时增加抗氧化物质含量，提高其抗氧化能力，从而减缓了超氧阴离子自由基和过氧化氢含量的持续升高。

Abstract:

【Objective】 In order to study the changes of photosynthetic characteristics and the contents of antioxidant substances of alfalfa during cold adaptation.【Method】 The 4-week-old seedlings of 10 alfalfa varieties were cold-adapted at 4 ℃ ，and their chlorophyll content，osmotic pressure，relative electric conductivity，photosynthetic characteristics，the contents of reactive oxygen species and antioxidant substances were measured on the 0 th，7 th， and 14th days，respectively.【Result】 The results showed that in the early stage of cold adaptation （0~7 d），the cell membrane was damaged，resulting in ion leakage and increased the relative conductivity of leaves. As the cold adaptation process continues （7~14 d），the amount of ion leakage decreased，the relative conductivity decreased，and the cold resistance of alfalfa was initially formed. Cold adaptation decreased the contents of chlorophyll a and chlorophyll b，net photosynthetic rate，actual photochemical efficiency of PS Ⅱ，and maximum photochemical efficiency of PS Ⅱ in alfalfa.【Conclusion】 The contents of osmotic pressure，ascorbic acid，oxidized glutathione and reduced glutathione of alfalfa seedlings increased continuously during cold adaptation. The osmotic pressure and concentration of cell fluid were increased to enhance the osmotic regulation ability of cells. At the same time，the content of antioxidant substances increased and the antioxidant capacity enhanced，which could reduce the content of superoxide anion free radical and hydrogen peroxide.