| Southern edge of Junggar Basin, an important economic zone of Tianshan Mountains, occupys an significant position in political, economic and cultural status. Therefore shelter forests should be created to protect the existing ecological environment, which is extremely severe now as a result of weather and human impact. But the shortage of water made the method aimed at brackish water to solve the problem of the water usage on agriculture and forestry. But as the utilization of brackish water on irrigation is complex and dual, the irrigation with brackish water remains to be solved. The research on the selection of plant, the effect of brackish water on the growth of forest and the specific measure of irrigation need to be conducted.The following conclusions can be drawn in this research:In the height of 0-160cm, the salt accumulated in the soil as the the water shortage due to the low irrigation water quota leading the water cannot permeated deep down in the soil. The electrical conductivity increased with the increasing of irrigation water quota. This is owe to that in the condition of higher irrigation water quota, desalination of soil occurred as the water can permeated into soil deep down. So the electrical conductivity is higher in the condition of higher irrigation water quota than lower irrigation water quota, which indicated that the equilibrium relationship between the electrical conductivity and irrigation water quota could be existed. Besides, the electrical conductivity is higher when the irrigation cycle is shorter. As the salt in the soil is moving with the migration of water, so the water content is in concert with the electrical conductivity in vertical distribution. And in the same period of irrigation, the peak value of water content is decreased as the water permeated deeper in the soil.In arid environmental conditions, the difference of water condition will lead to the diverse growth and morphology of plant. The crown diameter of plant is higher when water is sufficient, in which the basal diameter and the diameter at breast height increased in proportion and the tree also grow faster. Short supply of water will inhibit the grow of overground part of tree, resulting in the disbalence between the growth of the basal diameter and the diameter at breast.The activity of protective enzyme in plants increased as the raising of physiological stress on the plants. Plants will produce and accumulate MDA, proline as the stress reached to a certain degree, which inhibit the growth of plant. The water flow changed in single-peak type, the minimum at 2 o'clock at noon. The critical stress on the plants will lead to the greater changing magnitude of water flow which will be lower in morning and at noon. And the change is difficult to recover to normality. Additionally the plants resist the stress from arid environment and ions change through the metabolism of diverse ions and micronutrients. The analysis illustrated that the content of K+ increased in plant irrigated by brackish water. While there is antagonism relationship between K+ and Na+ K+ and Na+, Mg2+ presented negative correlation. As K+ significantly positively correlated with Ca2+, there was negative relationship between Mg2+ and Ca2+. The content of microelements Fe, Mn, Cu, Zn appeared ascending trend.From all the analysis in the research we can draw that twice irrigation with the irrigation water quota not less than 100m3 per acre is sufficient to the survival of populus in growth season. The irrigation by brackish water in this area should be rationally arranged. Fourth irrigation with the irrigation water quota of 80m3 per acre will bring fine growth of plants and the rational utilization of water. Also the quality of soil can be maintained in this condition. |
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