Soil Salt Dynamic And Winter Wheat Stress Regulation Mechanism Under Brackish Water Irrigation

In recent years,the shortage of water is becoming more and more serious.In agricultural irrigation,the rational development and utilization of brackish water resources is an important way to solve the problem.Science of brackish water irrigation can not only control salt accumulation in the soil and reduce soil salinization problems,but also can maintain the normal growth of crops,ensure the quality of crop production and economic benefits.The object of this experiment is winter wheat.The experimental area is located in the Xia Wa town of Zhanhua District,Shandong Province.The experiment is divided into two parts:the field test and the bucket experiment.By setting up a variety of irrigation schemes,First,the population scale of Winter Wheat(agronomic traits,yield and photosynthesis,etc.)were analyzed.Then,the leaf scale of Winter Wheat(leaf green content,light response curve and chlorophyll)were analyzed.Last,the physiological responses of Winter Wheat under the brackish water irrigation and the regulation mechanism of stress regulation are gradually explored.We can get the results of the reasonable irrigation scheme for brackish water.The main conclusions of this paper are listed as follows:(1)3g/L brackish water for irrigation can supply the soil moisture content effectively,also,it has a certain leaching effect on the soil salt in the test area,as a result,the soil salt in the root area of winter wheat moves downward.The accumulation of the salt water irrigation scheme is bigger than the accumulation of fresh water irrigation scheme,and the cumulative situation of the two irrigation scheme is greater than the accumulation of three irrigation schemes.The irrigation scheme of fresh water-micro brackish water-brackish water is better than that of fresh water and micro brackish water irrigation scheme.(2)Brackish water irrigation will bring on the salt stress,it will inhibit the growth of plant and the accumulation of dry matter.When faced with water stress caused by no irrigation,LAI would decrease,but it would promote the growth of root system of winter wheat.It is very necessary to irrigate at the filling stage.Compared with the two irrigation,three irrigation can effectively alleviate the water stress of crops,increase the grain filling rate and prolong the time of grain filling,so the use of 3g/L's brackish water can ensure the final yield of winter wheat.(3)Brackish water irrigation will affect the function and photosynthesis of leaves.Low concentration of salt stress does not cause the decrease of chlorophyll in leaves,and the effect of 3g/L brackish water on chlorophyll content is less,while 5g/L brackish water will reduce the chlorophyll content of leaves.In jointing stage,irrigation with brackish water of 3g/L can promote physiological growth of winter wheat,and proper salt stress will promote photosynthesis of crops.The effect of stomatal factors on Photosynthesis in the early stage of brackish water irrigation was mainly stomatal factors.With the salt entrying into the soil root area,the effect of salt stress on photosynthesis was mainly non stomatal factors.Salt stress inhibited the activity of leaves and reduced photosynthesis of winter wheat.(4)The rule of light response curve under brackish water irrigation is analyzed.Salt stress would change the use of effective light radiation,and the use of 3g/L brackish water irrigation would promote the utilization efficiency of winter wheat to low effective light radiation.Irrigation with brackish water by 5g/L will affect the leaf structure of winter wheat and reduce the response of leaves to high effective light radiation,and ultimately lead to the decline of photosynthesis.In addition,salt stress will increase the initial fluorescence of crops,reduce the maximum fluorescence yield of leaves and reduce the conversion efficiency of intrinsic light.The brackish water of 3g/L can alleviate crop water stress to some extent,and increase the physiological growth of crops under salt stress.(5)Winter wheat is resistant to salt regulation by changing ionic concentration and soluble substance concentration.When the soil salinity is too high,winter wheat will fix a lot of Na~+in roots and reduce the effect of Na~+on aboveground parts.At the same time,the consideration of K~+of the crops will enhance the salt resistance.Proline and soluble sugar will increase obviously when the crops are under high salt stress.When the ion concentration is too high in winter wheat,the decomposition of soluble substances can relieve the situation of"ion poisoning"in crops.