1. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Northwest A&F University Yangling Shaanxi 712100 China
2. Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement Provincial Key Laboratory of Applied Botany South China Botanical Garden Chinese Academy of Sciences Guangzhou China
3. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources Yangling Shaanxi 712100 China