1. Division of Pomology, National Institute of Fruit Tree Science, Tsukuba, Ibaraki 305, Japan (S.K., Y.K.-M., M.F.)
2. BioScience Center, Nagoya University, Nagoya, Aichi 464–01, Japan (M.M., M.T.)
3. Doctoral Program in Agricultural Science, University of Tsukuba, Tsukuba, Ibaraki 305, Japan (T.S.)
4. Faculty of Agriculture, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan (I.Y.)