1. Faculty of Agronomy College, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia 010070, P. R. China
2. Key Laboratory of Herbage & Endemic Crop Biotechnology, Ministry of Education, School of Life Science, Inner Mongolia University, Hohhot, Inner Mongolia 010070, P. R. China
3. Inner Mongolia Academy of Agricultural and Animal Husbandry Sciences, Hohhot, Inner Mongolia 010031, P. R. China