The Experimental Study On Field Water Use Coefficient Estimation And Its Influencing Factors In Southern Paddy Field

With the continuous development of Chinese social economy,the water shortage problem become increasingly serious,water resources has become an important factor restricting the social and economic development.Rice is one of the main crops in China,there is large planting area and high water consumption.There are important theoretical significance and practical value for accurately calculating water use coefficient in rice field and improving agricultural water use efficiency to study the water use coefficient calculation as well as discuss the major problems during its calculation.In this paper,the meteorological data of field irrigated rice experiment inYangzhou Jiangdu District Water Resources Research Station year in 2016 were analyzed of.The water requirement,growth and development status,yield and field water use coefficient of rice were studied under different irrigation patterns(shallow-frequent irrigation,wet-shallow irrigation,wet irrigation and controlled irrigation).The effects of temperature,relative humidity,wind speed and sunshine duration on the evapotranspiration of rice were studied by using regression analysis method.The main results are as follows::1.Based on the experimental measurement,the irrigation amount were 622 mm,585 mm,563 mm and 535 mm,respectively,and the water use coefficients were 0.78,0.83,0.87,0.91,respectively.The WP were 1.05kg/m3,1.05kg/m3,1.09 kg/m3,0.98kg/m3,respectively.The WPI(irrigation water productivity)were 1.31kg/m3,1.34kg/m3,1.43kg/m3,1.33kg/m3 and 1.30kg/m3,and the WPETc(the water productivity of evapotranspiration)were 1.87 kg/m3,1.80kg/m3,1.84kg/m3,1.63kg/m3.2.The growth and production of rice were affected by different irrigation patterns.The highest yield was 8156 kg/hm2 obtained under shallow-frequent irrigation,followed by wet irrigation of 8033 Kg/hm2,the yield under wet-shallow irrigation and controlled irrigation were 7855 kg/hm2,7130kg/hm2.The highest plant height was 101.70cm under the wet irrigation,while it is the lowest of 96.92cm under controlled irrigation.The average plant height in the mature period was 98.49cm under shallow irrigation,,that was 97.73cm under wet-shallow irrigation,ranked the third.The highest thousands seed weight was 27.65g harvested under controlled irrigation,followed by those of 27.45g and 26.85g under shallow-frequent irrigaton and wet irrigation,respectively.The minimum thousands seed weight is 25.51g under wet-shallow irrigation.3.Based on the analysis of field data in studying area,the relationship between field water use coefficient and irrigation amount was established under the certain circumstance of soil texture and field engineering condition.The influencing mechanism of irrigation on field water use coefficient was analyzed preliminarily,and the variation tendency of water use coefficient with irrigation amount was obtained.