1. State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, P.O. Box 61, Lanzhou 730020, China
2. Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
3. Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences, Key Laboratory of Tropical Crops Germplasm Resources Utilization, Ministry of Agriculture, Danzhou 571737, China