1. Dep. of Agronomy; Iowa State Univ.; Ames IA 50011
2. Dep. of Crop and Soil Sciences, Center for Applied Genetic Technologies; Univ. of Georgia; Athens GA 30602
3. This journal paper of the Iowa Agric. and Home Econ. Exp. Stn., Ames, IA, Project No. 6631, was supported by the Hatch Act and State of Iowa funds
4. Dep. of Statistics; Iowa State Univ.; Ames IA 50011
5. Dep. of Ecology, Evolution, and Organismal Biology; Iowa State Univ.; Ames IA 50011