亚硒酸钠和硒酸钠对小白菜生长生理特性的影响

Effects of Selenite and Selenate on Growth and Physiological Characteristics of Pakchoi

以小白菜品种秦白2号为材料,采用盆栽试验研究了不同浓度亚硒酸钠[Se(IV)]和硒酸钠[Se(VI)]胁迫对小白菜生长生理特性的影响及其生理机制,为土壤硒污染修复及其合理开发利用提供理论依据.结果表明,Se(IV)≤10.0 mg·kg-1时,小白菜的叶长、叶宽显著下降,而生物量没有受到显著影响;Se(VI)≤1.0 mg·kg-1时,叶长、叶宽、生物量没有显著变化;更高浓度处理时,叶长、叶宽、生物量均随外源Se(IV)和Se(VI)处理浓度的增大而急速下降.Se(IV)≤40.0 mg·kg-1和Se(VI)≤20.0 mg·kg-1处理均对小白菜叶片叶绿素含量无显著影响,但更高浓度外源Se(IV)和Se(VI)却显著抑制了叶绿素合成.低浓度外源Se(IV)和Se(VI)均使小白菜叶片谷胱甘肽过氧化物酶(GSH-Px)活性上升,膜质过氧化物(MDA)含量下降,对超氧化物歧化酶(SOD)活性、过氧化氢酶(CAT)活性及脯氨酸含量无显著影响;高浓度硒使MDA含量、脯氨酸含量及SOD活性上升,而使GSH-Px活性和CAT活性下降;外源Se(IV)和Se(VI)均使过氧化物酶(POD)活性降低.研究发现,低浓度外源Se(IV)和Se(VI)均提高了小白菜的抗氧化作用,从而促进小白菜叶片叶绿素的合成和生长,高浓度时则相反;低浓度硒的抗氧化作用和高浓度硒的过氧化作用均以Se(VI)大于Se(IV).说明硒酸钠的有效性和毒害作用均大于亚硒酸钠.

Pot experiments were conducted to study the effects of selenite and selenate on growth and physiological characteristics of the pakchoi and its physiological mechamism.The results showed that leaf length and width of pakchoi reduced significantly but DW biomass of pakchoi was not affected by selenite when added less than 10.0 mg·kg-1.Leaf length and width and DW biomass of pakchoi were not affected by selenate in the concentration of 1.0 mg·kg-1 treatment.At high selenium concentrations,leaf length and width and DW biomass of pakchoi reduced sharply with the increase of selenium concentration irrespective of selenite or selenate treatment.Chlorophyll content was not affected by selenium when selenite was added less than 40.0 mg·kg-1 or selenate less than 20.0 mg·kg-1,while chlorophyll formation was restrained with the increase of selenite and selenate concentration thereafter.At low selenium concentrations of selenite and selenate treatment,an increase in glutathione peroxidase（GSH-Px）activity and a decrease in lipid peroxidation products and MDA contents were observed.However,superoxide dismutase（SOD） activity,catalase（CAT） activity and proline contents were not affected at low selenium concentrations.At high concentrations,selenite and selenate enhancing the accumulation of MDA and proline,but GSH-Px activity decreased.Furthermore,CAT activity decreased but SOD activity increased at high selenium concentration.Peroxidase（POD） activity decreased irrespective of selenite or selenate added to the soil.The antioxidantive effects at low selenium concentration and pro-oxidantive effects at high selenium concentration of selenate were stronger than that of selenite.The bioavailablity and toxicity of selenate on pakchoi was bigger than that of selenite under current experimental conditions.