Eucommia Ulmoides Stem Cutting Seedling Growth And Photosynthetic Physiological Response Under Soil Drought And Study On Introduction And Cultivation

In this paper, four different ages (1a,3a,5a,10a) of Eucommia seedlings were taken as materials. The pot experiment of soil moisture under artificial control and field cultivation experiment were carried out. The survival rate, germination rate, leaf color changing period, deciduous period and the height and ground diameter growth of Eucommia ulmoides were studied to draw out the climate suitability in Jinzhong basin in Shanxi. In water control condition of 3 soil moisture gradients, the leaf nutrient content, water physiological indexes, leaf anatomy index, photosynthetic physiology index and growth index were studied to reveal the response of Eucommia ulmoides to the drought conditions, which can provide the basis for Eucommia to grow in the Jinzhong area, especially in hilly semi-arid and semi humid region. The main results are as follows:(1) The time of Eucommia ulmoides germination and leaf expansion was in mid April to mid May. The defoliation was in November. The height, ground diameter of one year old seedings, new branch length, base diameter of the older ages of Eucommia plant growed rapidly in 7 to 9 month. Then the plant height and new branch length decreased gradually while ground diameter and new branch base diameter continued to grow until October.1 year old Eucommia growth season is 229 days,3 year old Eucommia growth season is 204 days,5 year and 10 year old Eucommia growth season is 190 days.(2) Soil drought significantly decreased the shoot dry weight and root. The decrease of net photosynthetic rate was due to stomatal limitation under moderate drought conditions. The decrease of net photosynthetic rate was the result of stomatal limitation and non stomatal limitation under severe drought. Under drought stress, the light utilization ability was narrow; the light of environment adaptability was reduced; consumption of dry matter was increased. Thereby drought reduced the dry matter accumulation and inhibited the growth of Eucommia ulmoides. With the increase of drought degree, non photochemical quenching coefficient significantly increased, which showed that the leaves of Eucommia ulmoides significantly increased thermal dissipation to release excess absorbed light energy, thereby protecting optical system from destruction.(3)The diurnal variation of gas exchange parameters showed a single peak curve under sufficient water supply, while the diurnal variation of the diurnal variation of the Shuangfeng curve showed a significant photosynthetic depression. Soil drought reduced transpiration rate, but the leaf stomatal density and leaf density increased, thus in a certain extent improved the transportation efficiency of water and nutrients and reduced the loss of moisture.(4) In order to adapt to the environment of water shortage in the semi arid region and guarantee the Eucommia ulmoides normal growth, The soil moisture content can be controlled to about 30% of the field capacity.