1. School of Agriculture and Biology, Shanghai Jiaotong University, 800, Dongchuan Road, Shanghai 200240, People's Republic of China E-mail: yinshengli@sjtu.edu.cn; xiaoyiqun@163.com; qiujiangping@hotmail.com; daiyiqi@hotmail.com
2. INRA, Agrocampus Rennes, CIRAD, UMR 1069, Sol Agronomie Spatialisation, F-35000, Rennes, France E-mail: paul.robin@rennes.inra.fr