| Heuchera micrantha,the native American plant,which is a rare color leaf shade,is widely used in the native American landscape.After the introduction of the cultivated varieties from abroad,the cultivated land in the northern region was well cultivated and domesticated as a good old root ground flower.As it is a hardy perennial herbaceous flowers,can even survive-15?low temperature,the high temperature in summer is a big problem of the Heuchera micrantha's introduction to the southern region of the primary consideration.This article selects the autumn,obsidian,red peppers,three different varieties to 25?and 30?,35?and 40? high temperature treatment(as control)by 25?,were studied systematically under high temperature stress of three varieties of performance form,leaf anatomical structure,physiological and biochemical features,explore the response mechanism of Heuchera micrantha under the high temperature stress.The thermal resistance of these three plants was evaluated by the method of membership function analysis,and the mechanism of heat resistance was discussed,which provided the theoretical basis for the introduction of the plants in the south of China.The main results are as follows:(1)from the external appearance,with the intensification of high temperature stress,all three kinds of plants have different degrees of wilting,drying,and loss of green.Suffer symptoms of order in order for the obsidian,red pepper,autumn,and the obsidian under 40? treatment will suffer the most serious,from the external morphological changes can be very intuitive see,obsidian behave worst during the heat stress,autumn ornamental value at high temperature is higher than the other two varieties.(2)from the perspective of blade anatomy,there are certain differences in three different varieties.In this study,the thickness,blade thickness and vein thickness of the bars in the autumn were relatively large,and the tissue structure of the leaves was less loose.The thickness of the palisade tissue thickness,leaf thickness and vein thickness of the red pepper and obsidian were relatively small,and the tissue structure of the leaves was relatively loose.It shows that the heat resistance of autumn is higher than that of red pepper and obsidian.(3)according to the physiological and biochemical indexes,there are significant differences among different species,and there are significant differences in physiological and biochemical index changes under different temperature treatments.MDA content,free proline content,soluble sugar content,relative electric conductivity were significantly increased with the increase of temperature,chlorophyll a and chlorophyll b,total chlorophyll content,anthocyanins content also fell to different extent,leaf water content,soluble protein content and SOD,POD,CAT and protective enzyme activity change law is inconsistent.Through the comprehensive analysis of the three varieties were able to withstand the 30? treatment,35? high temperature started to influence the growth and physiological metabolic activity,40? high temperature seriously inhibit the growth of the plant,and will bring irreversible damage to plants.(4)the single index cannot explain the strength of the plant resistance to heat,the comprehensive evaluation method of membership grade function is used to the 35? high temperature treatment of three varieties' heat resistance sorting is: autumn > obsidian > red pepper;the sorting of the heat resistanceof three varities Under 40?high temperature treatment is: autumn > chillies > obsidian.According to the appearance of external morphology and the restoration of plant after stress,the heat resistance of 3 Heuchera micrantha varieties was ranked as: autumn > red pepper > obsidian. |
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