Resistance Of Chrysanthemum Morifolium Induced By Temperature Pretreatment

Temperature is very important to flowers' growth,lasting high temperature would potentially make a tremendous injury to Chrysanthemum(Chrysanthemum morifolium), and result in reducing its ornamental values and restraining its applied regions.Therefore, it is very important to improve the heat and cold tolerance of chrysanthemum with the aim of reducing the cost of production;improving the security of overwintering on land.There are some reports about the improvement of the ability of the plants resisting the adversity by pretreated with high and low temperatures.However,little is reported on chrysanthemum.There were four treatments involved in the trial:the leaves and petals of chrysanthemum treated at 50℃high temperature stress after pretreated with 38℃and -5℃low temperature stress after pretreated with 4℃;the cuttings of chrysanthemum 'Jinba' treated at 50℃high temperature stress after pretreated with 40℃and -5℃low temperature stress after pretreated with 40℃.And then the changes of electrolytic leakage(EL), content of malondialdehyde level(MDA),chlorophyll,soluble protein,proline and activity of superoxide dismutase(SOD),5'-nueleotidase and peroxidase(POD)were measured after high or low temperature stress with different times.The aims were to study the effects of heat shock on the thermotolerance,of the cold acclimation on the cold tolerance and of the heat shock on the cold tolerance.The main results were as follows:1.The leaves and petals of chrysanthemum pretreated showed that compared with the non-treatment chrysanthemum the heat acclimation(38℃)treatment inhibited the increasing of electrolytic leakage and the content of MDA,and descended the speed of decomposition of soluble protein in leaves and flowers.The decomposition of chlorophyll was also inhibited and the activity of 5'-nucleotidase was enhanced in leaves.It suggested that the acquisition of thermotoleranee had been induced by heat shock.2.For the leaves and petals of chrysanthemum,the electrolytic leakage and the content of MDA in leaves treated with cold acclimation(4℃)were lower than those of non-treated,the contents of soluble protein and proline and the activities of SOD and 5'-nucleotidase kept higher levels compared with those of controls.The results indicated that the cold tolerance of chrysanthemum was improved by cold acclimation treatment.3.For the cuttings of chrysanthemum 'Jinba',the electrolytic leakage and the content of MDA in leaves treated with heat acclimation(40℃)were lower than those of non-treated,the contents of soluble protein and proline and the activities of SOD and POD kept higher levels compared with those of controls.The results indicated that the heat tolerance of chrysanthemum was improved by heat shock treatment.4.For the cuttings of chrysanthemum 'Jinba',the electrolytic leakage and the content of MDA in leaves treated with heat acclimation(40℃)were higher than those of non-treated,the contents of soluble protein and proline kept lower levels compared with those of controls,and the activities of SOD and POD showed a complicated change,and was lack of orderliness.The results indicated that the cold tolerance of chrysanthemum was not improved by heat shock treatment.