1. Dep. of Crop, Soil, and Environ. Sciences; Univ. of Arkansas; Fayetteville AR 72701 U.S.
2. Agriculture and Agri-Food Canada; Unit 100-101 Rt. 100 Morden MB R6M 1Y Canada
3. College of Agriculture; Northwest Univ. of Agriculture and Forestry; Yangling Shaanxi 712100 P.R. China
4. Indiana Crop Improvement Association and Dep. of Agronomy; Purdue Univ.; West Lafayette IN 47909 U.S.