3种外源物质对干旱胁迫下火力楠幼苗生理特性的影响

Effects of Three Exogenous Substances on Physiological Characteristics of Michelia macclurei Seedlings under Drought Stress

为探究外源物质对干旱胁迫下火力楠(Michelia macclurei)幼苗的缓解效应和调节机制,以1年生火力楠幼苗为材料,在幼苗叶面喷施不同浓度甜菜碱(BT)、茉莉酸甲酯(MeJA)和氯化钙(CaCl_(2))溶液,并将幼苗置于浓度为30%的聚乙二醇(PEG-4000)溶液中模拟干旱胁迫;设置两组对照(CK和D),CK为正常生长处理,D为模拟干旱胁迫处理。测定干旱胁迫第1、第3和第7天幼苗叶片叶绿素含量、相对电导率、渗透调节物质含量和抗氧化酶活性,并采用模糊隶属函数法综合评价不同处理下幼苗的抗旱性。结果表明,干旱胁迫第7天,D的火力楠幼苗叶片叶绿素含量、相对电导率、可溶性糖和可溶性蛋白含量及POD活性均显著高于CK,CAT活性高于CK,说明火力楠幼苗具有一定抗旱性。不同浓度3种外源物质处理对干旱胁迫下火力楠幼苗的生理特性均有不同程度影响。综合评价结果表明,MeJA在提升火力楠幼苗抗旱性方面表现较好,其中3.0 mmol/L MeJA处理下幼苗抗旱性表现最好;CaCl_(2)表现次之,其中5 mmol/L CaCl_(2)处理下幼苗抗旱性表现较好,仅次于3.0 mmol/L MeJA处理。

In order to explore alleviation effects and regulation mechanisms of exogenous substances on Michelia macclurei seedlings under drought stress,one-year-old M.macclurei seedlings were used as materials.After spraying different concentrations of betaine(BT),methyl jasmonate(MeJA)and calcium chloride(CaCl_(2))on leaves of seedlings,seedlings were placed in 30%polyethylene glycol(PEG-4000)solutions to simulate drought stress.Two groups of control were set up(CK and D).CK was normal growth treatment.D was simulated drought stress treatment.Chlorophyll contents,relative conductivities,contents of osmotic adjustment substances and activities of antioxidant enzymes in leaves of seedlings were measured on the 1st,3rd and 7th days after drought stress,and drought tolerances of seedlings under different treatments were comprehensively evaluated by fuzzy membership function method.Results showed that on the 7th day after drought stress,chlorophyll content,relative conductivity,contents of soluble sugar and soluble protein,and POD activity of M.macclurei seedlings in D were significantly higher than those in CK,and CAT activity in D was higher than that in CK,which indicated that M.macclurei seedlings had certrain drought tolerance.Treatments with different concentrations of three exogenous substances had different effects on physiological characteristics of M.macclurei seedlings under drought stress.Results of comprehensive evaluation showed that MeJA had better effects in improving drought tolerance of M.macclurei seedlings,and drought tolerance of seedlings in 3.0 mmol/L MeJA treatment was the best.Followed by CaCl_(2),and drought tolerance of seedlings in 5 mmol/L CaCl_(2)treatment was better,sec ond only to 3.0 mmol/L MeJA treatment.