Articles
INFLUENCE OF DIFFERENT ROOTSTOCKS ON THE GROWTH AND YIELD OF THE APRICOT TREES
Affinity of apricot varieties to different rootstocks predetermines the rate of uniting of the two components (rootstock and scion) and is the basis for the longevity of engrafted trees.
Good knowledge of the growth vigour which different rootstocks induce in apricot varieties is of great importance for determining the appropriate scheme of planting and distances between the trees.
The ability of rootstocks to assimilate nutritive substances and water from soil is also of great importance since the productivity of trees depends on it.
In some countries with well developed apricot production, strictly determined variety-rootstock combinations are utilized in each specific apricot growing region distinguished by specific soil and climatic conditions (7, 8, 9, 10).
The data provided by Liacu (1960) indicate, that in Romania, apricot grafted on plum rootstock live for a period of 40—50 years, but grafted on apricot rootstock it lives for a period of 9 to 24 years.
Opposite results are obtained in Czechoslovakia where, under experimental conditions, best results have been obtained with apricot rootstock (9). For the conditions existing in Italy Eideghelli (8) recommends to use as rootstock the apricot variety Canino, pointing out that Janka plum (Prunus cerasifera) does not give good results.
The controversies as regards rootstock for apricot speak of the very complex nature of this problem and of the need of studying it with a view of establishing the most suitable rootstocks for each apricot-growing region.
In Bulgaria, apricot seedlings and to some extent seedlings of Janka plum (Prunus cerasifera), plum and almond are most oftenly used as rootstocks for apricot (2, 3, 4, 5, 6). There are not sufficient data for establishing the most appropriate variety-rootstock combinations (4, 5).