1. Key Lab. of Mollisols Agroecology, Northeast Institute of Geography and Agroecology; Chinese Academy of Sciences; Harbin 150081 China
2. Univ. of the Chinese Academy of Sciences; Beijing 100049 China
3. Innovation Academy for Seed Design, CAS; Harbin 150081 China
4. Stockbridge School of Agriculture; Univ. of Massachusetts; Amherst MA 01003 USA