脱落酸、水杨酸和钙对黄瓜幼苗抗冷性的诱导效应

为了探明脱落酸(ABA)、水杨酸(SA)和氯化钙(CaCl2)对黄瓜幼苗抗冷性的影响及其生理机制,以津优35号黄瓜幼苗为试材,叶面喷施0.1 mmol.L-1 ABA、1 mmol·L-1 SA和10 mmol·L-1 CaCl2,以喷洒去离子水为对照(CK),在光照培养箱中进行低温(昼/夜温度8℃/5℃,光量子通量密度为100μmol.m-2·s-1)处理.结果表明,低温胁迫可使黄瓜幼苗的冷害指数、电解质渗漏率(EL)、丙二醛(MDA)和过氧化氢(H2O2)含量显著升高.随着胁迫时间的延长,过氧化物酶(POD)活性逐渐升高,而超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽还原酶(GR)活性先升高,后降低；脯氨酸与可溶性糖含量明显增加.胁迫前经ABA、SA和CaCl2预处理,黄瓜幼苗的冷害指数分别比CK降低50.0％、40.0％和47.1％,EL和MDA含量的增加幅度明显减小,胁迫初期H2O2含量增加幅度大于CK,但24 h后呈下降趋势,72 h时分别比CK降低27.9％、27.5％和34.4％；抗氧化酶活性及脯氨酸、可溶性糖含量显著高于CK.说明ABA、SA和CaCl2对黄瓜幼苗抗冷性有明显的诱导效应,这种效应与抗氧化酶活性提高和渗透调节能力增强有关.

Inductive Effect of Abscisic Acid, Salicylic Acid, and Calcium on Cold Resistance of Cucumber Seedlings

The purpose of this paper is to investigate the effect and its mechanism of abscisic acid(ABA),salicylic acid(SA) and calcium chloride(CaCl2) on cold resistance of cucumber(Cucumis sativus L.) seedlings.Cucumber(cv.Jinyou 35) seedlings pretreated with a foliar spray of 0.1 mmol·L-1 ABA,1 mmol·L-1 SA,10 mmol·L-1 CaCl2,or distilled water(control) were displaced into growth chambers and treated under low temperature(day/night temperature is 8 ℃/5 ℃).The results revealed that low temperature stress significantly increased the chilling injury index,electrolyte leakage(EL),contents of malondialdehyde(MDA) and hydrogen peroxide(H2O2).The peroxidase(POD) activity increased gradually with stress time,whereas,activities of superoxide dismutase(SOD),catalase(CAT),and glutathione reducase(GR) increased at first and reduced later.The contents of proline and soluble sugar enhanced remarkably with stress time.Pretreated with ABA,SA or CaCl2 before exposure to stress condition,the cold injury indexes of cucumber seedlings decreased by 50.0%,40.0% and 47.1%,respectively.ABA,SA and CaCl2 treatment seedlings showed significant lower increase degree in EL and MDA content compared with control seedlings.At the initial stress stage,the increase degree of H2O2 content in ABA,SA and CaCl2 treatment seedlings were higher than that of control,but the H2O2 content in ABA,SA and CaCl2 treatment seedlings trend to reduction after 24 h,and were lower by 27.9%,27.5% and 34.4% respectively at 72 h,compared with that of control.The ABA,SA and CaCl2 treatment seedlings showed significant higher antioxidase activity and contents of proline and soluble sugar than those of control.These data suggest that ABA,SA and CaCl2 can induce cold resistance in cucumber seedlings,and the inductive effect may be related to the observed increase in antioxidase activity and osmoregulation capability.