Effect Of Calciumon Cold Tolerance Of Cucumber Seedlings Induced By Salicylic Acid And Abscisic Acid

The purpose of this research is to investigate the effect of calcium, salicylic acid（SA）and abscisic acid（ABA） on cold resistance of cucumber （Cucumissativus L.） seedlings and therole of calcium on salicylic acid and abscisic acid-induced cucumber chilling tolerance usingthe ’Jinyou35’ cucumber seedlings as test materials. The results are as follows.1. Chilling injury index of cucumber seedlings, electrolyte leakage （EL）,malondialdehyde （MDA） and hydrogen peroxide （H2O2） contents were increased significantlyunder the low temperature. During the stress period, the peroxidase （POD） activity rosecontinuously, whereas the activity of superoxide dismutase （SOD）, catalase （CAT）,glutathione reductase （GR） increased at first, and then decreased; the proline and solublesugar contents rose significantly. The chilling injury index of cucumber seedling whichtreated by0.1mmol/L ABA,1mmol/L SA, or10mmol/L CaCl₂before low temperaturestress was lower than CK significantly; the increased range of EL, MDA contents wasdecreased significantly; antioxidant enzyme activity, proline content, and soluble sugarcontent were significantly higher than CK. These results indicated that ABA, SA and CaCl₂have inductive effect on cold resistance of cucumber seedlings obviously, which influencedby the antioxidant enzyme activities and osmotic adjustment.2. In the early period of low temperate, MDA content of seedlings treated with CaCl₂+SA increased slowly with higher the antioxidant enzyme activity and reducedglutathione（GSH）, ascorbic acid（AsA） contents. MDA content of seedlings treated with LaCl₃+SA, and CPZ+SA, increased quickly with lower the antioxidant enzyme activity and GSH,AsA contents. After24h stress, there was no significantly different between each treatment onMDA content and antioxidant enzyme activity. After72h stress, the difference on EL, chillinginjury index between CaCl₂+SA and SA treatment was not significantly, but the LaCl₃+SAand CPZ+SA treatments were lower than SA treatment. These results could show that CA²⁺and CAM have an important function on the SA-induced cold tolerance of cucumberseedlings, and the synergistic effect of CaCl₂and SA is not obvious.3. Under the low temperature, the differences on EL, MDA content, and chilling injuryindex between CaCl₂+ABA and ABA treatment is not significantly, but LaCl₃+SA andCPZ+SA treatments were higher than ABA treatment significantly; antioxidant enzymeactivity and endogenous ABA content of CaCl₂+ABA treatment were high than ABAtreatment, but LaCl₃+SA and CPZ+SA treatment was lower than ABA treatmentsignificantly. These results demonstrated that CA²⁺and CaM took part in the ABA-induced cold tolerance of cucumber seedlings, and had no obvious affect in promoting cucumberseedlings’ cold tolerance.