State Key Laboratory of Grassland and Agro-Ecosystems,School of Life Sciences,Lanzhou University,Lanzhou 730000,China;
State Key Laboratory of Grassland and Agro-Ecosystems,College of Pastoral Agriculture Science and Technology,Lanzhou University,Lanzhou 730000,China;
Ministry of Natural Resources and Forestry,Timmins District,5520 Hwy 101 E,South Porcupine,ON,PON 1 HO,Canada;
actual; evapotranspiration; reference; evapotranspiration; crop; coefficient; meteorological; factors; biotic; factors;