1. Dept. of Plant and Soil Sciences Mississippi State Univ. 117 Dorman Hall, Box 9555 Mississippi State MS 39762
2. Crop Genetics Research Unit USDA‐ARS P.O. Box 345 Stoneville MS 38776
3. Mississippi Water Resources Res. Inst. Mississippi State Univ. Box 9547 Mississippi State MS 39762
4. Delta Research and Extension Center Box 197 Stoneville MS
5. USDA‐UV‐B Monitoring Network, Natural Resource Ecology Lab. Colorado State Univ. Fort Collins CO 80523