With the exception of mechanical and transport functions, it is proved that the rootstock takes part in synthesis of simple organic materials and hormonal materials too.
The rootstock has a selective influence on the receiving level of mineral materials from the soil.
It actively influences the photosynthesis (Syrbu et al., 1983), saccharide contents in buds, the flower bud frost hardiness of grafted varieties (Nitransky, 1985), contents of vitamins (Serafimova, 1984),. fruit colouring and consistency and also fruit weight (Syrbu-Stajan, 1982). The rootstock conclusively changes the size and also a habitus of the apricot top (Paunovic-Teeovic, 1968, Crossa-Raynaud-Audergon, 1987). The rootstock has a significant influence on plant decline percentage.
The character of influence on a grafted variety is considerable decided with rootstocks health, especially of point of view of compatibility, growth-rate and yield of apricots as well as in the other stone-fruits (Dosba, 1991).
The rootstock cannot be changed during the apricots lifetime.
That is why it is necessary to give it an extraordinary attention because its function is long-term and complex.
In this days the rootstock-set and its variability gives certain manoeuvreing possibilities to use different environmental conditions.
Much work has been carried out during the last 30 years into the rootstock research and breeding for apricots.
The extensive approach to rootstock breeding, which mainly consisted in a selection from spontaneous natural resources (especially generatively propagated rootstocks) has been changed in purposeful rootstock's breeding for different conditions.
A remarkable amount of vegetatively propagatable rootstocks has also been bred and introduced to practice in latest years.
A lot of varieties of wider Prunus genus was utilized in the rootstock breeding.
But the number of species, which the most used rootstocks for apricots come from, is not large.
They are especially species Prunus armeniaca L., Prunus cerasifera Ehrh., Prunus persica L., Prunus insititia L. and Prunus domestica L. In these days there are increasing rootstocks formed by interspecific hybridization, whose application depends only on vegetative propagation.
The most significant characters which must be estimated in selection of apricot rootstocks are: ability to: propagation, anchorage, growth-rate, uniformity, compatibility, adaptability to environment, disposition for a formation of root suckers, influence on a precocity of bearing after planting and on yield, decline,