1. Guangdong Engineering Research Center for Grassland Science, College of Life Science, South China Agricultural University, Guangzhou, P. R. China
2. Department of Chemistry and Bichemistry, College of Biology & Pharmacy, Yulin Normal University, Yulin, P. R. China
3. Department of Garden and Flower, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, P. R. China
4. Guangxi Key Laboratory of Agricultural Resources Chemistry and Biotechnology, College of Chemistry and Food Science, Yulin Normal University, Yulin, P. R. China