1. College of Agronomy and Biotechnology China Agricultural Univ. Beijing 100193 China
2. Scientific Observation and Experiment Station of Wuqiao for Crops with High Water Use Efficiency Ministry of Agriculture Cangzhou 061807 China
3. Institute of Cereal and Oil Crops Hebei Academy of Agriculture and Forestry Sciences Shijiazhuang Hebei Province 050035 China