Studies On Physiological Characteristics Effect Of Pseudolarix Kaempferi Seeding Under Shading Treatment And High Tempe-Rture Stress

Pseudolarix kaempferi is a type of rare tree and ancient preserved plant,which is only procduced inChina in the world. In accordance with the rules and regulations,it is protected by China country. It has abeautiful shape and straight branches, which the leaves are dense. Pseudolarix kaempferi is known as oneof the top five garden trees of the world. This study regards seedling of Pseudolarix kaempferi as toresearch object. It is used to survey the ability to resist shading treatment and high temperature. Thefollowing is the main result of the study.(1). While the shading was different, the physiological changes of Pseudolarix kaempferi weredifferent. As stress degree increased, the content of chlorophyll and leaf water content firstly increased andthen decline. POD became lower and then increased as the shading stress degree, yet chla/chlb and solubleproteins of seedling declined. The change of proline content are not obvious until95%shading treatment.On95%shading treatment, proline content increased significantly. MDA content increased as the shadingstress degree.On shading stress, the proline, MDA reached significantly positive correlation; chla/chlb,soluble proteins reached significantly negative correlation.(2). While high temperatures was different, the physiological changes of Pseudolarix kaempferi weredifferent, even if, under the same temperature, while the hours of high temperature were different, thephysiological changes of Pseudolarix kaempferi were also different. As the results of the study shows, ashigh temperature stress degree increased and extension of time, leaf electrolyte osmotic ratio and MDAincreased. The content of chlorophyll became lower as high temperature stress increased and the extensivetime, however, SOD content firstly increased in high temperature treatment of0-12h and then significantlydeclined after24h of high temperature treatment. Under high temperature treatment, soluble proteinsincreased. The soluble sugar content increased under30℃å'Œ35℃, and then it declined significantly after2h of40℃.(3) Under the high temperature, the lethal temperature is45.1℃by the Logistic equation. On thebasis of the variation of index under shading treatment, it showed that the shading≤70%, Pseudolarixkaempferi seedings could grow normally, the shading≥95%, Pseudolarix kaempferi seedings couldn'tgrow normally.