1. Inner Mongolia Research Center for Prataculture, State Key Laboratory of Vegetation and Environmental Change, Institute of Botany; Chinese Academy of Sciences; Beijing China
2. Inner Mongolia Academy of Agricultural and Animal Husbandry Sciences; Hohhot China
3. University of Chinese Academy of Sciences; Beijing China
4. Department of Biology; University of Kentucky; Lexington Kentucky
5. Department of Plant and Soil Sciences; University of Kentucky; Lexington Kentucky