| Populus euphratica is the main body of the desert riparian ecosystem in the tarim river basin,and plays an important role in improving the ecological environment,curbing desertification and protecting biological diversity.In this paper,by studying the different development stages of p.euphratica heterophyll structural character(morphology and structure)and functional properties(photosynthetic physiological,moisture physiological and physical feature)under different soil moisture change rules and their differences,in order to clarify Yang heterophyll structural character(morphology and structure)and functional properties of adaptation of drought environment strategy.The results are as follows:(1)8 and 16 size order in distribution and drought in suitable soil moisture conditions,are showed with the increase of tree height,leaf shape index decreased,increased leaf area,leaf dry weight and leaf thickness and specific leaf area decreased leaf morphological characters of the change,the main area of vascular bundle of arteries and veins,the primary xylem area of arteries and veins,arteries and veins xylem and vascular bundle area ratio,duct area,the tube structure properties such as the increase in the number of changes,and special-shaped blade structural traits have close relationship with heterophyll in height.Under the two soil moisture conditions,the heteromorphic leaves at the upper part of the canopy had more obvious drought-resistant structure characteristics than those at the lower part of the canopy,and the morphological and anatomical structure of heteromorphic leaves of eupoplar under the soil drought conditions had more obvious drought-resistant structure characteristics than those under the appropriate soil moisture conditions.(2)Under suitable water conditions and soil drought conditions,the net photosynthetic rate,transpiration rate and stomatal conductance of 8-diameter and 16-diameter heterophyllleaves all increased with the increase of tree height,and the net photosynthetic rate,transpiration rate and stomatal conductance showed a significant/extremely significant positive correlation with the sampling height.Under the two soil moisture conditions,the heterophyll leaves at the top of the tree canopy had stronger photosynthetic capacity,and the heterophyll leaves under the soil drought condition had stronger photosynthetic capacity than those under the suitable water condition.(3)Under appropriate water conditions,the relative water content of 8-diameter special-shaped leaves showed an increasing trend with the increase of tree height,and the water potential of 16-diameter special-shaped leaves showed an increasing trend.The relative water content,leaf water potential and 13 c showed a significant/extremely significant positive correlation with the sampling height,and a significant negative correlation with the moisture saturation deficit.Under the condition of soil drought,the relative water content of steps 8 and16 showed a trend of increasing first and then decreasing,and the instantaneous water use efficiency of steps 16 showed an increasing trend with the increase of the sampling height,13 c showed a significant positive correlation with the sampling height.Under suitable water conditions,the leaves in the upper part of the crown have better water environment than those in the lower part.Under the condition of soil drought,the water environment in the middle part of the tree crown was relatively good,and the water conditions of 8 and 16 diameters under the suitable water conditions were better than those under the condition of soil drought.(4)Under appropriate water conditions,the proline content of 8 and 16 diameters increased with the increase of tree height,while only 16 diameters increased with the increase of tree height under soil drought conditions.Under the two soil moisture conditions,the content of malondialdehyde in 8 and 16 steps increased with the increase of tree height,and the content of proline,malondialdehyde and soluble protein showed a significant/extremely significant positive correlation with the sampling height.Under the two soil moisture conditions,the heteromorphic leaves at the top of the tree crown were subjected to greater stress and showed stronger osmotic regulation ability.The osmotic regulation ability ofeuphratica euphratica under the soil drought condition was stronger than that under the suitable water condition.(5)Under different soil moisture conditions,water physiological indexes are closely related to structural and functional indexes.Under suitable water conditions,the thickness,catheter density and catheter number of the leaves had a great influence on the water content of the leaves,and the relative water content had a great influence on the net photosynthetic rate and transpiration rate.Under the condition of soil drought,leaf shape index,leaf area,leaf dry weight,main xylem area and the ratio of main xylem to vascular bundle area to leaf water content had a greater influence,and 13 C had a greater influence on net photosynthetic rate and transpiration rate.The results showed that the relative water content had a more direct influence on the photosynthetic capacity under the suitable water conditions,while the water use efficiency had a greater influence on the photosynthetic capacity under the soil drought conditions.(6)When the p.euphratica face soil moisture drought,with the increase of tree height,p.euphratica diversifolious morphological anatomy structure characteristics of drought resistance,increase in photosynthetic capacity and water environment is bad,by stress is larger,but the osmotic regulation substances content is higher,osmotic regulation ability is stronger,formed to deal with a survival strategy of soil drought stress. |
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