作者单位:Institute of Plant Genetics and Biotechnology, Slovak Academy of Sciences, Akademická 2, P. O. Box 39A, 950 07 Nitra, Slovakia[1]Czech University of Agriculture in Prague, 165 21 Prague 6 - Suchdol, Czech Republic[2]Constantine Philosopher University, Hlinku 1, 949 74 Nitra, Slovakia[3]Mlynany Arboretum, Slovak Academy of Sciences, 951 52 Slepèany, Slovakia[4]