Effects Of Nitrogen Application On Water Consumption Of Cupressus Chengiana S.Y.Hu Seedling

The arid valley of upper reaches of Minjiang River is the worst ecological environment regions. Water restrictions is the key factor of vegetation restoration and reconstruction in the regions, In order to answer the question of vegetation restoration and reconstruction in the arid valley of upper reaches of Minjiang River, this paper set Cupressus chengiana S. Y. Hu as research objective, studyed on the influences of Water Consumption of the main forestation tree species-Cupressus chengiana S. Y. Hu under the different soil water conservation and different levels of nitrogen. Taking seedling water consumption, growth indicators, photosyntheitc rate, plant physiology indicators as the test indicators. This paper provide a scientific basis for nitrogen fertilizer to promote plant growth under the drought conditons, also improve the plants' water situation and utilizing efficiency,etc. And it also provided a scientific guidance for forestation while speeded up the vegetation restoration of the regions. The reseach results are as follows:(1) The impact of nitrogen fertilizer work on water consumption of seedling. In the growing season, under a certain soil water conditions, the nitrogen fertilizer applying can reduce the water consumption of seedling, In influences of water consumption of seedling, besides the nitrogen fertilizer, the soil water content is the main influencing factor. In the experimental, high nitrogen level can evidently reduce the water consumption when soil water content is 25%.(2) The impact of nitrogen fertilizer work on seedling growth indicators. At a low soil water condition, nitrogen fertilizer can effectively restrict the height of seedling, promote basal diameters growth, reduce the ratio of height to diameter; soil water content, nitrogen level and interaction of the two are main influential factors of seedling growth. different soil water content and different nitrogen fertilizer content impact on the every indicators of growth differently. Under the experimental conditions, in a certain range of soil water content (5%, 15%, 25%), nitrogen fertilizer can evidently increase the seedling qulity index, Moreover, the low nitrogen level can extraordinary improve the seedling quality index than high nitrogen level. (3) The impact of nitrogen fertilizer work on diurnal variation of net photosynthetic rate, transpiration rate and water use efficiency of seedling. There was a tend in net photosynthetic rate increasing and transpiration rate decreasing, but the level of nitrogen fertilizer have no evidencely impact on net photosynthetic rate and transpiration rate; Judging from the water use efficiency, nitrogen fertilizer could evidently increase the water use efficiency, but the level of nitrogen fertilizer had no evidencely impact on it; Under severe drought conditon (SWC = 5%), the non-nitrogen fertilizered seedling has the lowest water use efficiency and it has no significant changes in different time slots, but the water use efficiency of nitrogen fertilizered seedling had greatly improved and it had significant changes in different time slots.(4) The impact of nitrogen fertilizer work on plant physiology indicators. Under severe drought conditon (SWC = 5%), Nitrogen fertilizer decreace relative water content of leaves, MDA content and activity of SOD, so it increase the content of Chlorophyll, soluble sugar, soluable protein and Proline. The content of soluable protein and Proline are evidencely increase. Form the changes of the most indicators, nitrogen fertilizer improved the drought resistance in the aspect of plant physiology.