1. State Key Laboratory of Vegetation and Environmental Change; Institute of Botany; Chinese Academy of Sciences; Beijing 100093 China
2. Division of Plant Sciences 1-31 Agriculture Building; Univ. of Missouri; Columbia MO 65211
3. Key Laboratory of Plant-Soil Interactions; Ministry of Education; Center for Resources; Environment and Food Security; China Agricultural Univ.; Beijing 100193 China
4. Institute of Protected Agriculture; Chinese Academy of Agricultural Engineering; Beijing 100125 China