Physiological And Ecological Response Characteristics Of Winter Wheat Under Slight Saline Water Irrigation

The fresh water shortage has become an important limitation of our national economy and sustainable development factors,the development and utilization of saline water has become the important ways to alleviate the contradiction between water resources supply and demand.Reasonable saline water irrigation will not cause long-term soil salt accumulation,Moreover,it can ensure the stable yield and even improve the quality of crops.In this paper,Winter Wheat was used as the research object,field experiments were carried out in Xiawa of Zhanhua County.Under the four irrigation schemes,Response characteristics of growth index of Winter Wheat(plant height,leaf area and dry matter),water physiological indexes(leaf water content,stomatal conductance,transpiration rate and water use efficiency)and photosynthetic physiological indexes(chlorophyll content,intercellular CO2 concentration,leaf net photosynthetic rate)were analyzed systematically,the photosynthetic characteristic parameters were calculated and analyzed by using the light response curve model,and the reasonable irrigation scheme and irrigation system were proposed based on the characteristics of yield and soil salinity.Main conclusions include:(1)Saline water irrigation could increase the water use efficiency of winter wheat to some extent.Using saline water(3g/L)in the jointing-earing period,the leaf water content increased by 0.017 and the drought tolerance increased;There was no significant inhibitory effect on stomatal conductance of leaves,but had a limited effect on transpiration rate;Use of saline water(3g/L)during grain filling,the winter wheat leaf water content decreased 11.487% than fresh water irrigation,to promote early maturity wheat,stomatal closure or damage the pore structure,water desorption seriously;Under irrigation water conditions,leaf water use efficiency mainly by stomatal factors,in saline water irrigation,nonstomatal factors dominate,and saline water increase leaf water use efficiency some extent.(2)Using saline water in the filling period,the effect of winter wheat on Photosynthetic physiology was more obvious.In jointing-earing period using saline water(3g/L),It had little effect on chlorophyll content of leaves,but inhibited respiration intensity and increased net photosynthetic rate;Use of saline water(3g/L)during grain filling,compared with freshwater irrigation,leaf chlorophyll content decreased by 10.62%,precocious phenomenon of Winter Wheat is obvious,but the net photosynthetic rate increased with the presence of nonstomatal factors;Effect of salt on net photosynthetic rate of Winter Wheat mainly by nonstomatal factors,this effect accelerated the senescence of plants,especially in the period of grain filling,although the crop has a high accumulation ability of organic matter,the accumulation time is shortened and the yield formation is affected.The photosynthetic characteristic parameters obtained from the simulation of light response curve have the value of analysis.(3)The effect of saline water on the growth of winter wheat was very obvious.From jointing stage to heading,compared with fresh water irrigation,the plant height of wheat decreased by 7.004%,and the leaf area index decreased by 30.747%-40.444%;The effect of 3g/L saline water(T1)on plant height was not obvious during filling stage,however,the leaf area index decreased further,in which T1 decreased by 46.135% compared with T3,and the early maturity of wheat was obvious.The dry matter accumulation of wheat showed the phenomenon of T3>T4>T2>T1,the salt effect makes the wheat plant smaller and the quality of dry matter was lower;The root-shoot ratio of wheat was T4>T1>T2>T3,and water stress and salinity stress had the effect of promoting plant root development,but different degree of action.The use of 3g/L saline water in jointing-heading period can affect the number of wheat ears,and the application of 3g/L saline water at grain filling stage will affect the grain number and 1000 grain weight.But the salinity effect of T2 early decreased the bad effect of the missing grouting water on wheat grains and thousand grains weight of winter wheat.(4)Saline water irrigation was not shown to increase the degree of soil salinization.The salt dynamic law shows that the two irrigation regimes will not cause soil salinization to worsen in the past one year,but T1 will cause salt accumulation in the long-term irrigation,and T2 will not cause salt accumulation.(5)Under the condition of saline water irrigation,the growth and physiological characteristics of winter wheat were disturbed,and the T2 micro-saline water irrigation scheme can be obtained as the prototype of the scientific irrigation system in this research area.