Abstract: The development and maintenance of wetland ecosystems are controlled by hydrological processes, especially the stability of water supply. To ascertain the temporalspatial stability of water sources and water supply relations of the Hani Rice Terraces, we collected the monthly samples of terrace water, rainfall, and groundwater in different altitudes during the growing season of rice from May to October in 2015 (rainy season). We analyzed the hydrogen and oxygen stable isotopes of water as well as meteorological data in the study area. The results showed that, during the rice growth stages, the δ¹⁸O of rainfall had obvious amount effects of rainfall, with a correlation coefficient of -0.94. The δ¹⁸O altitude gradient of groundwater was -0.1‰/100 m, while the isotopic effect of terrace water was not significant. Rainfall and groundwater were the main water sources of terraces in the whole growing season. In the early stage of rainy season (from May to June), the main water sources of terraces were the previous terrace water and rainfall. In the mid-rainy season (from July to August), the main water source was rainfall. At the end of the rainy season (from September to October), groundwater became the main water source. During the whole growing season of rice, large part water supply of rice terraces was from rainfall and small part was from groundwater, with rainfall and groundwater supply of rice terraces distributed spatially as a watersupply mosaic. In summary, owing to the water supply of the three temporal periods and the spatial rainfall-groundwater mosaic characteristics, the Hani Rice Terraces keep stable and last for thousands of years.

Key words: grain nutritional quality, grain yield, summer maize, grain filling characteristics, nitrogen application rate