Study On Irrigation System And Water And Salt Transport Of Sugarbeet Under Shallow Drip Irrigation In Saline-alkali Soil Of Western Liaohe Plain

The West Liao River Plain is a typical semi-arid irrigated agricultural area in China.The contradiction between supply and demand of water resources is acute,and saline-alkali land is widely distributed.The development of irrigation technology for water saving and salt suppression,and the exploration of irrigation systems conducive to the efficient use of water resources and the reduction of salinity in the plow layer have become the only way for the sustainable development of agriculture in the region.As an economic crop widely planted in the West Liao River Plain,sugarbeet has the characteristics of high biomass,salt and alkali resistance.Because of its sensitive growth process to soil moisture change,it is necessary to select the appropriate irrigation system.As a new agricultural irrigation technology,the application of shallow-buried drip irrigation provides a new idea for the formulation of agricultural water-saving and efficient irrigation system in this area.Therefore,it is of great significance to study the high-efficiency water-saving irrigation system of sugar beet and the influence of different irrigation amounts on soil water and salt migration under shallow drip irrigation in the West Liaohe Plain,so as to promote the efficient utilization of local water resources and the sustainable development of agriculture.In this thesis,according to the percentage of soil moisture content in field water holding rate,five different irrigation treatments,high water（GS）,medium water 1（ZS1）,medium water 2（ZS2）,low water（DS）and control（CK）,were set up under shallow drip irrigation.The effects of different irrigation amounts on the growth and yield of sugar beet were analyzed,and the effects of different irrigation amounts on soil water and salt migration were revealed.On the basis of experimental research,the irrigation system of sugar beet in different hydrological years was simulated based on Cropwat model.The results will provide theoretical basis for the sustainable development of regional agriculture.The main conclusions are as follows:（1）310mm（normal year）and 273mm（wet year）irrigation treatment of sugar beet plant height,leaf area,dry matter maximum.Reducing irrigation amount of 30～40 mm is beneficial to increase photosynthetic rate,transpiration rate and intercellular CO₂concentration of sugar beet.In the growth period-sugar accumulation period,increasing irrigation quota will hinder the increase of photosynthetic rate,transpiration rate and intercellular CO₂ concentration of sugar beet.At the end of growth period,269 mm（normal year）and 241 mm（wet year）irrigation treatments are the best.（2）The water consumption during the leaf blooming period accounted for more than60%of the total growth period,and the daily water consumption intensity varied from5.13mm/d to 6.18mm/d.When the irrigation quota was 270mm（normal year）and 241mm（wet year）,the sugar beet yield and sugar yield were the best,with the average values of6.73×10⁴kg·hm^-2 and 0.74×10⁴kg·hm^-2 respectively.Compared with the local irrigation system,the yield increased by 7%～10%and 19%～25%,and the water saving was9%～36%.But the water use efficiency and sugar yield decreased with the increase of irrigation,250mm（normal year）and 220mm（wet year）irrigation treatment was greater than other treatments.（3）In the harvest period,the average total salt content,alkalinity and p H of each soil layer decreased by 10.37%,14.36%and 3%,compared with those before sowing.When the irrigation amount was 273 mm and the irrigation frequency was 6 times,the soil total salt content,alkalinity and p H decreased the most,which were 5.6%,40.8%and 4.9%lower than those before sowing on average.（4）Based on Cropwat model,the water requirement of sugar beet in different hydrological years was 588.7～703.6 mm,and the coupling degree of different hydrological years was wet year>normal year>dry year>extra dry year.The irrigation quotas were233.4 mm,267.4 mm,320.2 mm and 463.3 mm,respectively.The irrigation times were 6times,8 times,10 times and 11 times,respectively.Supplementary irrigation must be carried out during the root tuber growth period–sugar accumulation period to meet the water requirement of crops.