Studies On Physiological Response And Adaptability Under Drought And Heat Stress In Sedum. Plants

External morphology,physiological changes and adaptability were studied under drought and heat stress on six Sedum (Sedum hybridum,Sedum spectabile, Sedum hybridum ’Immeryrunchett’, Sedum sarmentosum, Sedum hybridum ’Immeryrunchett’ Sedum spuriumu ’Coccineum’).The main results were as follows:1. Heat tolerance of six Sedum. Plants were measured by electrical conductivity method.The results showed:The relationship between the temperature and the relative electricity conductivity varied in the’S’curve model,which was accorded with Logistic equation proven by sign ificance test Calculated with the formulas, the half lethal temperatures of the six Sedum. Plants were Sedum hybridum59.85℃、Sedum spectabile56.82℃、Sedum hybridum ’Immeryrunchett’53.55℃、Sedum sarmentosum52.61℃、 Sedum hybridum ’Immeryrunchett’51.86℃and Sedum spuriumu ’Coccineum’51.53℃. According to the half lethal temperature, the heat tolerance of six sedum. Plants was in the order of Sedum hybridum>Sedum spectabile>Sedum hybridum ’Immeryrunchett’> Sedum sarmentosum>Sedum hybridum ’Immeryrunchett’>Sedum spuriumu ’Coccineum’2. External morphology and physiological changes were studied under45℃high temperature stress to study the response in six Sedum. Plants.The results showed that: with serious level of heat stress, leaves of six Sedum. appeared curl、turned yellow、dried off and other symptoms. And different Sedum. had different degrees at different times. These expressions reflected their different heat tolerance. Throughout the stress process, little changes in relative water content, and chlorophyll contents reduced. Conductivity and MDA contents increased,and different Sedum. had distinct rate of increase. According to morphological characteristics and physiological changes, the results indicated that the order of heat resistance in six plants was:Sedum hybridum>Sedum spectabile>Sedum hybridum ’Immeryrunchett’>Sedum sarmentosum>Sedum hybridum ’Immeryrunchett’> Sedum spuriumu ’Coccineum’.3. External morphology and physiological changes were studied under drought and45℃high temperature stress’to study the response in six Sedum. Plants. The results showed that:with serious level of drought and heat stress, leaves of six Sedum. appeared dehydrate and curl、turned yellow、dried off and other symptoms.And different Sedum. had different degrees at different stages.These expressions reflected their different tolerance to drought and heat stress.Throughout the stress process, soil moisture、relative water content and soluble sugar decreased. Conductivity and MDA contents increased, and different Sedum. had distinct rate of increase. According to morphological characteristics and physiological changes, the resistance from highest to lowest to drought and heat in six plants was:Sedum hybridum,Sedum spectabile,Sedum hybridum ’Immeryrunchett’,Sedum sarmentosum, Sedum hybridum ’Immeryrunchett’ Sedum spuriumu ’Coccineum’.4. Under high temperature stress, exogenous SA can increase the content of soluble sugar and proline, and maintain the osmotic potential to reduce accumulation of MDA, and conducive to maintaining water content of Sedum. plants. While enhancing the SOD, POD and CAT activity,and slowed the rate of cell membrane lipid peroxidation, enhance the heat tolerance of Sedum. plants. Under drought and heat stress, spraying SA solution on six Sedum. plants. It can increase both proline and chlorophyll content, while reduce accumulation of MDA and leaf water. At the same time, improved SOD、POD and CAT activity. It improved the drought and heat resistance of Sedum. plants.5. Improved the heat resistance of Sedum. with spraying SA, CaCl2, H2O2,6-BA, and ABA solution at different extent.Different actions on heat resistance effection of six Sedum. plants with spraying different solution.