1. Northeast Research and Extension Center; Haskell Agricultural Lab.; Univ. of Nebraska-Lincoln; Concord NE 68728
2. Dep. of Agronomy, Throckmorton Hall; Kansas State Univ.; Manhattan KS 66506
3. Dep. of Agricultural and Forestry Sciences; Univ. of Tuscia; 01100 Viterbo Italy
4. Dep. of Plant Biology, Rutgers; The State Univ. of New Jersey; New Brunswick NJ 08901-8520