Photosynthetic Physiological Mechanism Of Morphological Establishment Of Pinus Koraiensis Planted Under Canopy

There are some obvious differences in the morphological characteristics of Pinus koraiensis under the forest and the all light,understanding the photosynthetic physiological mechanism of these differences,it has a great significance to the effective restoration and reconstruction of the mixed forest of Pinus koraiensis broadleaf.In this paper,the photosynthesis parameters and photosynthetic physiological characteristics of Pinus koraiensis under different opening degree conditions were studied,photosynthetic physiological mechanism of Pinus koraiensis under the different months and different lighting conditions was studied in the Taiping test area of Maoershan of Northeast Forestry University,in order to provide a scientific and effective reference for the better promotion of the growth of Pinus koraiensis.The main conclusions are as follows.(1)when K=2.0,its use of light energy was the most efficient,and it was most conducive to the growth of Pinus koraiensis.The net photosynthetic rate was generally greater than that in other opening degree when K=2.0,and the net photosynthetic rate reached the maximum in August.Stomatal conductance and intercellular CO2 concentration were the highest when K=1.0,and reached the maximum in August and September respectively.The transpiration rate had the highest value when K=2.5 and reached the maximum in August.(2)Under each opening degree,diurnal variation of photosynthetic effective radiation intensity of Pinus koraiensis was the single peak curve which increased first and then decreased,and reached the maximum respectively at 14:00 pm,and the maximum value of photosynthetically effective radiation intensity was maintained for each time period when K=2.5.The diurnal variation of photosynthetic rate of Pinus koraiensis was bimodal curve which increased first,then decreased,then increased,and then decreased,the net photosynthetic rate had the highest value when K=2.0.(3)Under each opening degree,the photosynthetic active radiation intensity and net photosynthetic rate of Pinus koraiensis grown in the south of adjacent broadleaf trees should be significantly larger than those in the other directions,the relationship was south>west>east>north,and there is a certain relationship between the two.When the number of broad-leaved trees around the Pinus koraiensis was more,the photosynthetically effective radiation intensity and net photosynthetic rate of Pinus koraiensis were smaller,However,when K=2.5,the regularity of the photosynthetic rate of Pinus koraiensis was the opposite.The effect of each factor on net photosynthetic rate was Ci>RH_S>Cond>Tleaf through path analysis,and through the change of different environmental factors and morphological characteristics,it was found that the growth condition of Pinus koraiensis was the best when K=2.0,and Pinus koraiensis could be normal growth under other opening degree,but the growth state is not as good as K=2.0.(4)Under each opening degree,the contents of chlorophyll a,chlorophyll b,carotenoids and chlorophyll in the leaves of Pinus koraiensis reached the maximum in July and August,and the four kinds of photosynthetic pigment content were the most in each month when K=2.0;In addition,the values of Chla/b and Chr/ChlT in leaves of Pinus koraiensis were the highest in 5 and 6 month when K=2.5,the values of Chla/b and Chr/ChIT in leaves of Pinus koraiensis were the highest in other months when K=2.0,and the overall presentation increased first and then decreased.(5)The contents of proline and soluble protein in the leaves of Pinus koraiensis were not significantly changed between the different opening degree and the different months,but the content of soluble sugar increased with the increase of the month,and there was a maximum when K=2.0.The water content and relative water content in the leaves of Pinus koraiensis were the highest in June,and there was a maximum when K=2.0.The cell membrane permeability and MDA(malondialdehyde)content in the leaves of Pinus koraiensis were the highest when K=1.0,and increased with the increase of the month.The superoxide dismutase(SOD)in the leaves of Pinus koraiensis had the highest content at smaller or larger opening degree and was the highest in May and September;The content of Catalase(CAT)was the highestat when K=1.0,and was the lowest when K=2.5,and it decreased with the increase of the month;The overall content of peroxidase(POD)was small,and there was no significant change between the different opening degree and the different months.Consolidate the results of this study,the following conclusions can be obtained:In the study of Zamu secondary forest,when the opening degree was K=2.0,the photosynthetic physiology of Pinus koraiensis was the best.