1. China Agricultural University Key Laboratory of Plant-Soil Interactions Ministry of Education, Department of Plant Nutrition 100193 Beijing China
2. University of Missouri Division of Plant Sciences 1–31 Agriculture Building MO 65211 Columbia USA
3. Abraham Baldwin Agricultural College Department of Agriculture 2802 Moore Highway GA 31793 Tifton USA
4. Peking University College of Urban and Environmental Sciences 100871 Beijing China