Study On The Resistance Of Heat And Waterlogging Of Clerodendrum Trichotomum

Taking the plants of Clerodendrum trichotomum Thunb as experimental materials, this essay is aimed to study the morphological and physiological characteristics in three high temperatures (35℃,40℃,45℃) and five waterlogging levels (water level respectively to a quarter, half, two-thirds, the surface and5cm above the surface of the thickness of pot soil). The changes of the morphological characteristics of the plants were observed and the relative water content, relative conductivity, MDA content, chlorophyll content, proline content, soluble sugar content, soluble protein content and SOD activities of the leaves were respectively determinated under different treatments. The main results are as follows:(1) Under high temperature stress, the effect of35℃processing to the plants is not obvious, and the plants grow fine. When the temperature is40℃, with the increasing of stress time, the morphological characteristics and physiological indexes have obvious changes. Leaves turn yellow and dry margin and spots appear. On the10th days of high temperature stress, relative conductivities, MDA content, chlorophyll content, proline content, soluble sugar, soluble protein and SOD activities were respectively1.42times,1.52times,0.29times,2.96times,1.06times,1.23times and1.07times of the control group. There is certain degree of damage to the plants, but it is not serious and its process is slow. Under45℃, the morphological characteristics and physiological indexes of the plants have dramatic changes in the shorter stress time. On thelOth days of stress, chlorophyll content, relative conductivities, MDA content, soluble sugar content, soluble protein content, proline content, and SOD activities were respectively0.11times,1.93times,2.64times,1.09times,1.54times,8.06times and1.13times of the control group and the leaves fully etiolate and part of them are dead meaning that there was seriously high temperature hurt to the plants.(2) The plants of Clerodendrum trichotomum can start the defense mechannism in the process of high temperature stress, which mainly increase osmolyte adjustment substance (proline, soluble sugar, soluble protein) content and cell antioxidant enzyme SOD activities to resist the high temperature environment. According to the correlation analysis and principal component analysis of the physiological indexes, the result that relative conductivity, MDA content, chlorophyll content, proline content and soluble sugar content could be used as the identification indicator of heat tolerance of Clerodendrum trichotomumcan be conclude. (3) Under waterlogging stress, the effect of water level to a quarter of the thickness of soil and water level to half of the thickness of soil on the morphological characteristics and physiological indexes of the plants of Clerodendrum trichotomum was not obvious and the plants grow well.The physiological indexes of the plants under the treatment of water level to two-thirds of the thickness of soil have obvious changes. After six days of waterlogging stress, the leaves wrinkles, their edges become curl, and the leaves wilt and droop because of gradual dehydration. The plants die after twelve days of waterlogging stress. On the12th days of stress, relative water content, chlorophyll content, relative conductivities, MDA content, soluble sugar content, soluble protein content, proline content, and SOD activities were respectively0.55times,1.07times,2.71times,1.76times,21.93times,2.03times,0.59times and0.80times of the control group. This is meaning that during the early time of treatment, the plants have a certain degress of resistance to waterlogging, but with the increasing of treated time the resistance decreases and the plants die after12days of waterlogging stress. When the water level is to the surface of soil, the morphological characteristics and physiological indexes of the plants have dramatic changes. The plants wilt because of rapid water loss afer2days of stress and the plants die after8days of stress. On the8th days of waterlogging stress, relative water content, chlorophyll content, relative conductivities, MDA content, soluble sugar content, soluble protein content, proline content, and SOD activities were respectively0.57times,1.12times,2.69times,1.70times,24.12times,2.72times,0.60times and0.77times of the control group. There was significant waterlogging damage to the plants. The effect of the treatment of water level to5cm above the surface of soil on the morphological characteristics and physiological indexes of the plants is basically the same as the water level to the surface of soil.(4) The plants of Clerodendrum trichotomum have strong osmotic adjustment capacity under waterlogging stress, mainly by increasing the proline and soluble sugar content to adapt to the waterlogging stress environment. The plants of Clerodendrum trichotomum have a certain ability to tolerate waterlogging, and the limit height of waterlogging is half of the thickness of soil. The results of the correlation analysis and principal component analysis of the physiological indexes show that relative water content, relative conductivity, MDA content, proline content, soluble sugar content and SOD activities could be used as the identification indicator of waterlogging tolerance of Clerodendrum trichotomum.