| This article shows two researches sharing the same purpose of the cold resistance of the subjects, such as Michelia polyneura, Michelia martinii and Michelia cavaleriei. One is under different temperature (10℃,5℃,0℃,-5℃,-10℃,-15℃); the other includes outsource of ABA and SA influences.The following is conclusions from the research.1. In the research of cold resistance.the content including Relative electric conductivity(REC),Chlorophyll(Chl), Malondialdehyde(MDA), Soluble protein(SP), Super oxide dismutase(SOD),Peroxidase(POD),Free proline(PRO)and Carotenoid in three kinds of Michelia plants increases in light of increasing temperature. As the temperature goes down, REC and MDA go the opposite way, SP, PRO, SOD, POD and Carotenoid climb up at first and fall down later, and Chl deceases notably.2. The difference has been found in the cold resistance of these three Michelia plants. Under low temperature, the relative conductance rate takes a shape of "S" according to the drop of the temperature. Comparing with the logistic formula, the similar rate is between 0.998 and 0.976, having a sound similarity. By the logistic formula, the half lethal temperatures of Michelia polyneura, Michelia martinii and Michelia cavaleriei are 6.69℃,-4.55℃,and-1.51℃.3. Correlation analysis on 8 indicators of cold resistance is possessed by the three Michelia plants. It shows that conductance rate is negatively correlated with Chl and SP. under low temperature, the cell damage of the three Michelia expands on the basis of more extravasation and increasing rate of relative conductance as the temperature goes up.Chl have a negative correlation with MDA. While MDA has a positive correlation with SOD and Pro as a way of sharing a same increasing trend of MDA, SOD and Pro.4. Using principle component analysis on the 8 indicators of cold resistance, Chi and MDA have closed relationship with the cold resistance.5. By function analysis, the cold resistance of 3 Michelia plants the same trend with the half lethal temperature. The top of cold resistance is Michelia polyneura, the last of cold resistance is Michelia cavaleriei, and Michelia martinii places between them.6. Various rate of ABA and SA infliction in the three Michelia plants under low temperature, at some point, decease the REC and MDA, increase SP and SOD, and alleviate the breakup of Chl comparing two outsource (ABA and SA), ABA has a greater influence on damage of cold resistance than SA.7. Under cold temperature, the rate of ABA and time of infliction have a notable influence on the cold resistance.As the rate is low (^25mg/L), the change of 8 indicators of cold resistance narrows slightly, showing a flat demonstration; as the rate is high (35mg/L≤ABA≤45mg/L), the cold resistance is significantly enhanced, which is based on decreasing REC and MDA as a way to alleviate the breakup of CHL, increase SP, lower SOD under low temperature, and decrease damage of cold temperature.As ABA is 45mg/L,the REC reaches the button. With CK, Michelia polyneura reduces to 18.3%, Michelia martinii decrease to 19.5%, and Michelia Cavaleriei drops to 22.1%. As ABA is above 45 mg/L, it decrease the efficiency of cold resistance. REC shows a climbing trend to increasing ABA, but it still shows inferior position with CK. Above all, the rate of 45mg/L and time of infliction between 30 and 40 days present the best result. When it is inflicted by 40 days, the comparison of REC and CK in 3 kinds of Michelia is reduced by 20.1%,24%, and 23.2%. |
