Abstract:
Abstract: Northeast China (NEC) is an important japonica rice production region, wherein rice production accounts for more than 50% of the national total japonica rice production. On the other hand, NEC region is one of the areas in China most susceptible to climate change, and the average temperature in NEC increased by 0.38°C per decade during the past five decades, while the precipitation decreased. The rice is produced under flood irrigation conditions (FL) in NEC which is facing a severe problem of scarcity in water resources. There is an urgent need for reducing water consumption for rice production by developing water-saving irrigation technologies. Therefore, to study the water consumption characteristics and rice consumption water use efficiency (WUEC) of rice under water-saving irrigation and FL patterns, and discuss the suitability of water-saving irrigation pattern, will provide a scientific basis for regional water-saving irrigation and play a vital role in rice production safety in Northeast China. Here, our goal is to examine the rice AWD (alternate wet and dry) suitability patterns based on a comprehensive assessment of rice yield and WUEC throughout NEC over the 36-year period from 1981 to 2016. In this paper, the agro-meteorological experiment station data which included weather, soil, phenology and management data were used to calibrate and validate the model based on nine cultivars selected for each region by using DRATES calibration program and trial-and-error method. The cultivar selected in the ORYZA simulation was the cultivar with the greatest number of years of cultivation during 1981 to 2007 within each province, and simulation with the longest-planted cultivar was more realistic and provided information for this study. The modeling was set up with the selected cultivar using the daily weather data from 1981 to 2016 for the 134 counties, rice crop data and soil data under FL and AWD management to simulate rice yield and water consumption. Based on model outputs, the WUEC was calculated for each weather station during the past 36 years and assessed at three province regional scales across NEC (Liaoning, Jilin and Heilongjiang Province). Then, combined with the yield and WUEC, the distribution patterns of rice AWD suitability were studied. The results indicated that, the rice yield decreased from southwest to northeast and showed a significant increasing trend during the period 1981 to 2016 under two irrigation patterns. The rice water consumption decreased significantly in the past 36 years and showed a decreasing trend from west to east. WUEC had increased significantly, with a decreasing distribution form north to south under FL and from east to west under AWD. Compared with FL, the rice yield under AWD decreased by 11% and varied considerably among locations (1% - 19%). However, the water consumption of rice decreased by 3% - 26%, with an average of 15%, and the averaged WUEC increased by 8%. The very suitable zone for AWD concentrated in southern Liaohe Plain of Liaoning Province, Fuyu-Jiaohe and Yanji region of Jilin Province, Southeastern Songnen Plain of Heilongjiang Province; suitable zone was in Linghai and Haicheng region in southern Liaohe plain of Liaoning Province, Yongji-Panshi-Liuhekou of central Jilin Province, Fangzheng and Fujin of central and eastern Heilongjiang Province; moderately suitable zone located in Dengta and Kaiyuan of the eastern Liaoning Province, Zhenlai and Shuangliao of Jilin province and Tieli and Raohe region of central and eastern Heilongjiang province; marginally suitable zone concentrated in Tieling and Qingyuan region of northeastern Liaoning Province, Changbai and Taonan of Jilin Province, and Fuyu-Lindian-Anda region of western Heilongjiang Province. It is of great significance to study AWD for saving water resources and ensuring high yield and high efficiency for rice in the research region.