土壤水分和氮素有效性对刺槐幼苗叶片活性氧产生和清除的影响

采用施加氮肥和人工控水的方法,以一年生刺槐幼苗为材料进行盆栽实验,探讨提高土壤氮素含量对不同土壤水分条件下刺槐幼苗叶片中活性氧产生和清除的影响。结果表明:(1)相同氮素水平下,降低土壤水分含量引起刺槐生物量和叶片光合色素含量降低,而过氧化氢(H2O2)含量升高;抗氧化酶系统中的超氧化物歧化酶(SOD)和过氧化物酶(POD)活性和过氧化氢酶(CAT)活性不同程度降低;抗氧化剂中抗坏血酸(ASA)含量和还原型谷胱甘肽(GSH)含量均有所提高;MDA含量逐渐升高,而同期细胞膜相对电导率显著升高。(2)相同水分条件下,提高土壤氮素水平显著提高了刺槐幼苗叶片光合色素含量,同时也一定程度提高了总生物量,显著降低了H2O2含量;SOD、POD和CAT活性不同程度升高;ASA含量和GSH含量则表现出不同程度下降;相对电导率显著降低同时MDA含量一定程度降低。因此,增加土壤氮素有效性可显著提高刺槐幼苗叶片光合色素含量,显著抑制活性氧的产生,一定程度提高总生物量和抗氧化酶活性,降低膜脂过氧化程度,从而有利于缓解干旱引起的伤害。

Effect of Water and Nitrogen Availability on the Generation and Scavenging of Reactive Oxygen Species in Leaves of Robinia pseudoacacia Seedlings

The response of reactive oxygen generation and scavenging has been studied in the leaves of annual Robinia pseudoacacia seedlings under manipulated nitrogen fertilizer and water supply.The results showed that:(1)At a constant nitrogen level,reduction of soil moisture decreased the content of total biomass and photosynthetic pigments ,elevated levels of hydrogen peroxide (H₂O₂);also with lessened water supply,the activities of superoxide dismutase (SOD),peroxidase (POD) and catalase (CAT) in antioxidant enzyme system all reduced;while contents of ascorbic acid (ASA) and glutathione (GSH) in antioxidant both increased;MDA content increased gradually and companying the relative conductivity significantly increased.(2)Then under the same water supply condition,improved soil nitrogen levels dramatically increased photosynthetic pigment content as well as the total biomass but significantly reduced the H₂O₂ content;it also enhanced the activities of SOD,POD,and CAT to different degrees;still with more available nitrogen,ASA content and GSH content declined,respectively;the content of MDA and the relative conductivity showed a reduction.In conclusion,the increasing of soil nitrogen content could significantly improve the content of photosynthetic pigments and inhibit the generation of reactive oxygen;it also increase the total biomass,enhance the activities of antioxidant enzymes to a certain extent,reduce the degree of cell membrane-lipid peroxidation.These responses are helpful to alleviate the drought-induced injury to the plants.