BREEDING OF ROOTSTOCKS WITH HETEROSIS EFFECT SUITABLE FOR GERMAN PRUNE AND FUNDAMENTAL PLUM VARIETIES IN CZECHOSLOVAKIA
In the half of last century field orchards were planted with German Prune. As planting material were used trees on their own roots and rootshoots of Durancie, which were grafted with German Prunes in the nursery already. For a lack of these materials, sowing of German Prune stones began. Their germination was bad and their growth was weak. Intergrafting was introduced in that way, that the plum seedling was grafted with one of the vigorous plum varieties in the root neck (Belle de Louvain, The Czar, Count Althann's Gage or Tragedy), but in the crown with German Prune or some else noble plum variety.
As there was a great demand after German Prune trees, the nurserymen examined other rootstocks as seedlings, St. Julien (from France), Durancie and Myrobolan-Cherry Plum (from France, Italy, Bulgaria). The best results were obtained by propagating plum varieties on Myrobolan. From the beginning