1. Dep. of AgronomyKansas State Univ.ManhattanKS66506
2. State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop BiologyCollege of Agronomy, Shandong Agricultural Univ.Taian271018China
3. Dep. of Crop and Soil SciencesWashington State Univ.PullmanWA99164‐6420