Effects Of Autumn Irrigation Model On Soil Water And Salt Changes,Wheat Yield And Water Use

In view of the current situation of serious waste of water resources and low water use efficiency in crop production in Hetao Irrigation District.This study takes spring wheat in Hetao Irrigation District as the research object and aims at water save and increase production.Under different autumn irrigation time and irrigation water volume conditions,systematic analysis of changes in soil moisture,soil salinity,groundwater table,before autumn irrigation and after autumn irrigation and before spring sowing and photosynthetic characteristics,material accumulation,yield and quality formation and water use difference,clarify the suitable autumn irrigation system for wheat in Hetao irrigation district.Provide a basis for establishing a water-saving and high-yield wheat technology system in Hetao Irrigation District.（1）Under different autumn irrigation model the interaction of autumn irrigation time and autumn irrigation norm has a greater impact on soil moisture content and soil salinity.Late autumn irrigation treatment can replenish groundwater,it can ensure the utilization of groundwater during the growth period of the next year and reduce soil p H and soil p H value is kept in a small range during wheat spring sowing.Under the suitable autumn irrigation quota of 1500m³·hm^-2in late autumn the 0～40cm soil moisture content of the soil surface layer has a large and significant increase and significant reduction in soil salt content.Soil desalination rate reaches 22.87%.The soil moisture content and salt content during the spring wheat sowing period and the entire growth period are maintained at a relatively high and appropriate level and the soil salt content is maintained within an appropriate range.（2）Autumn irrigation time and autumn irrigation norm have different degrees of influence on wheat seed germination,plant morphology,photosynthetic characteristics and material accumulation.Compared with the non-autumn irrigation treatment（CK）the seed germination rate and seedling emergence rate are significantly improved,among them the late autumn irrigation treatment is the best the emergence rate of the next spring reaches 96%.Wheat plant height,upper three leaf length,leaf width,leaf area and leaf area index,photosynthetic potential,population growth rate,dry matter accumulation under the late autumn irrigation treatment were higher than those of the early autumn irrigation treatment.1500m³·hm^-2under a suitable fall irrigation norm the green loss of wheat leaves was slower at grain filling stage,net photosynthetic rate,Fv/Fm value can be maintained at a high level,maintain strong photosynthetic activity,there by promoting the accumulation of photosynthetic products.（3）Under different autumn irrigation model With the increase of autumn irrigation norm the wheat yield and constituent factors all showed a trend of first increasing and then decreasing.Grain yield reached the highest under the treatment of autumn irrigation quota of1500m³·hm^-2.Relatively speaking,The number of spikes and grain yield in the late autumn irrigation treatment were significantly higher than that of the early autumn irrigation treatment.The interaction between autumn irrigation time and autumn irrigation norm has extremely significant effects on the number of spikes,grains per spike and 1000-grain weight.Increased with the fall of autumn the total water consumption of crops during the whole growth period is increasing and the group water use efficiency is significantly reduced.Regression analysis shows that wheat grain yield water use efficiency（WUE）and autumn irrigation quota all have a quadratic curve relationship.The highest yield and WUE fall irrigation quota are1500m³·hm^-2and 1258m³·hm^-2respectively.In summary,The most suitable autumn irrigation time for wheat in the Hetao irrigation area to achieve a unified water-saving and increased production is around October 25th and the quota for autumn pouring is 1258m³·hm^-2～1500m³·hm^-2.