1. Delta Research and Extension Center; Mississippi State University; Stoneville 38776
2. International Institute of Tropical Agriculture (IITA), c/o IIAM-PAN; Nampula Mozambique
3. Tobaco Research Institute; Chinese Academy of Agricultural Sciences; Qingdao 266101
4. Department of Land, Air and Water Resources; University of California; Davis 95616
5. Ayres Delta Implement Inc.; Leland MS 38756
6. Oklahoma Agricultural Experiment Station; Oklahoma State University; Stillwater 74078
7. Zhejiang University; Zhejiang China 310029