| Agapanthus is perennial herb flower that are native of South Africa and most part of the Southern Africa continent. This paper regards a cultivated variety of Agapanthus as experimental materials, we observed these materials and measured some characters of physiology such as chlorophyll(Chl) content, changes of electrical conductivity, soluble saccharine (S) content, soluble protein(Pr) content, Pro content, MDA content, activities of SOD,POD. This paper studies seedling growth phase, including changes and mechanisms of chlorophyll content, changes of soluble matter, cell membrane system degree of damage and POD activities under the high temperature stress, at the same time, analyzed relativity of these indexes, the main results are as follows:(1)Under the 30℃and 35℃high temperature stress, the Agapanthus seedlings do not have a remarkable result.(2) The CMT of Agapanthus seedlings is 60.79℃by the Logistic equation.(3)Agapanthus seedlings were exposed to simulated 40℃high temperature tress that inhibits their normal growth. Seeing from changes of leaves forms of Agapanthus seedlings, it changes greatly along with extending process time. After three days, some of leaves become yellow, they appear moderate dehydration; after 5days, most of leaves become yellow, appear severe dehydration; at the same time, a few leaves lost activities; After 6 days, nine tenths of leaves become yellow and dry, most of leaves lost activities. It can be seen that 40℃is limiting temperature of Agapanthus under normal operation. So in real life of shanghai, 40℃can inhibit normal growth of Agapanthus and effect there ornamental expressions.The physiology indexes of Agapanthus seedling have severe change under 40℃. S, Pr and Pro is the plant body inside permeate to regulate the material importantly, Its content variety does not fulfill same alike under the high temperature stress. Along with the increase of the high temperature stress, Agapanthus leaves Pr content have the decrease of different degree, Leaf organization of Agapanthus seedling S content with the force time increase. On the fourth day, the content of S rise obviously, the content of S is 3.38 times higher than relative CK. In many analysis's, which indicates: the content is quite different on the third and sixth day under the high temperature stress. The Pro contents of seedling leaf is the similar to the others who specialize in: the Pro content rises obviously on the fourth day, and on the sixth day the content is 15.34 times higher than relative group. In many analysis's, which indicates that the content is quite different on the third and sixth day under the high temperature stress. So the accumulation of S and Pro may be the protect reaction of high temperature, and the accumulation is the origin of the high temperature stress. And the decrease of Pr needs research further.Under 40℃high temperature stress of the Agapanthus seedlings, the SOD activity increased in the leaves, then reduce, eventually to stabilize. Agapanthus seedlings for the first month process of adaptation to high temperature, resistant high temperature; But in the four days, gradually suppressed to stabilizing. SOD activity of multiple analysis, the results showed that the treatments compared with the control, after six days of high temperature stress, it has no significant difference, after two days, it has significant difference compared to the control. Agapanthus seedlings under high temperature stress, POD activity with the same changes experienced by the environmental stress. It indicates the conditions are harmful or affect the Agapanthus seedlings. Agapanthus seedlings under high temperature stress in leaves POD have shown a marked increase, but with the extension of stress, on the fourth day POD activity rose to the highest, then declined.Under the 40℃high temperature stress, the cell of Agapanthus have peroxidization, so the permutations of leaf cell membrane increased, and electrolyte exosmosises, and Electrical conductivity increased, the content of MDA rises, and the cell of Agapanthus have big destruction. The relative Electrical conductivity increased at different degrees, which increased by 11.76% and 20.59% in relative to original group on the first or second day under the high temperature stress, but it isn't obvious; on the third day the figure is higher 41.18% than relative group obviously, and on the sixth day it is highest. The content of MDA of seedling leaf increased at different degrees in relative to original group under the high temperature stress, and on the fifth or sixth day the change of the content of MDA is obvious. The content of MDA is 1.18 times higher on the fourth day; the content of MDA is 2.21times higher, and on the sixth day the content of MDA increased to 3.13 times.When Agapanthus seedling is suffered the 40℃high temperature stress, the chlorophyll will be changed. The chlorophyll a and b in the cell will be changed in difference illumination. When it being suffered the force of high temperature, the sum of chlorophyll will be depressed in evidence. It will be get the rock bottom at the fourth day, then it will step up. The chlorophyll a is the same with the sum. But chlorophyll b is not changed. The degree of chlorophyll b is decreased lower than chlorophyll a, the ratio a/b declined relatively, the ratio is on the decline, but at the same time the ratio rise slowly, and the tendency is stable. The results indicate the value chlorophyll a/b is between 2.04 to 4.28.
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