| Purple Majesty is one of the twelve prized varieties chosen in 2003 by AAS who has the good reputation of "Oscar" of world breeding industry, and it is highly valuable in scientific researches and ornamental. In recent years, Purple Majesty has been extended to the garden construction in various cities as its excellent ornamental, and Purple Majesty will most likely be important green plant in the city. The correlative physiological and biochemical indexes of Purple Majesty were determined when it was under the high and low temperature stresses which were simulated, at the same time, salicylic acid's mitigating the negative effects of temperature stress on Purple Majesty was also studied. By this study, we hope to elucidate a series of response mechanisms of Purple Majesty and achieve the goal of further increasing the resources of the landscape ground cover plants in Chongqing. The flowing is the result:1. Both high temperature and low temperature made the root activity rapidly dropped, the root totallength,root totalsurarea and root volume were simultaneously lower than that of the normal control group. SA made the plant's root totalsurarea under the high temperature stress and the root activity under the low temperature stress significantly increased.2. Under the high temperature stress, the contents of Chla and Chlb were firstly increased and then decreased and eventually lower than the control; The content of Car was slightly lower than the control; Pn and Cond were significantly decreased, and Trmmol were gradually increased, but the maximum intensity was significantly lower than control, from the blow, we indicated that high temperature stress damaged to the structure of the chloroplast, and Purple Majesty's photosynthesis was obstructed.While when Purple Majesty was under the low temperature stress, the contents of Chla and Chlb were firstly increased and then decreased and eventually lower than the control; The content of Car was significantly reduced; Pn and Cond were basically at the lowest level; Ci was significantly increased and Trmmol was briefly risen in the early, and then it had been kept at a low level, Which showed that low temperature stress caused serious damage to Purple Majesty's photosynthesis, and the photosynthesis were almost at a standstill.SA significantly increased the plant's Chlb and Chla content,Pn,Cond,Gs and Trmmol which was under high temperature stress. But under the low temperature stress, SA made Pn increased, and Ci gradually reduced, but SA did no significant effect on Cond and Trmmol.3. High temperature stress cause adverse effects on Purple Majesty. High temperature made the relative conductivity and the content of MDA significantly increased. The content of Soluble Protein was reduced when it was the seventh day and the content of free proline was increased at the first phrase of the high temperature. The contents of MDA,the soluble sugar and the free proline were higher than that of the normal control group, which showed that Purple Majesty was more sensitive to the low temperature.In the high temperature group, SA not only reduced the relative conductivity and the content of MDA, but made the content of soluble protein and soluble sugar increased. While in the low temperature group, to a certain degree, SA increased the Purple Majesty's cold tolerance because it increased the content of soluble sugar and reduced the content of free proline.4. When Purple Majesty was under the high temperature stress, POD activity was lower than that of the contrast and SOD activity and APX activity basically kept the contrast's level. But when it was under the low temperature stress, SOD activity and APX activity rose quicker than that under the high temperature stress, and POD activity was also lower then that in contrast plant, while, although GR activity was higher then that in contrast plant, it lower that than that under the high temperature stress, by which, we got the conclusion:low temperature stress made the cell regulated more active oxygen, and it did more serious harm to Purple Majesty.Under the high temperature stress, SA made SOD activity increased and POD activity reduced, while, GR activity and APX activity had no obvious changes. Under the low temperature stress, SA reduced the largest value of SOD activity and relayed the time of getting to the largest value, meanwhile, POD activity,GR activity and APX activity were also reduced. |
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