Vigor reduction of sweet cherry varieties by dwarfing rootstock is well known, but the mechanism by which a rootstock induces dwarfing is not well understood. Plant hormones have been associated with dwarfing mechanism. This study was conducted, with the main purpose of determining the correlation between of endogenous abscisic acid (ABA) and indole acetic acid (IAA) and vigor of 10 selected dwarf mahaleb (Prunus mahaleb L.) genotypes. Endogenous IAA and ABA levels of selected dwarf genotypes were evaluated, which indicated significant differences for most traits. The IAA level in the shoot bark was the highest in H24 and lowest in M96 genotypes, while ABA level in the shoot bark was highest in M96 and lowest in H14. The mean ABA content decreased as the invigoration capacity of the genotype increased. ABA generally is regarded as an inhibitor of elongation. In our experiment, the endogenous ABA content was negatively correlated with shoot growth. ABA: IAA ratio in shoot bark decreased with increasing genotype vigor. ABA: IAA ratio of the dwarfing genotype M96 was about 1.118. Correlation coefficient showed a significant correlation between crown width, trunk diameter, crown volume, total IAA, total ABA, IAA: ABA and tree vigor. The concentration of ABA in shoot bark showed a good relationship with vigor, thus the content of this phytohormone in shoot bark could be a useful marker of dwarfing character in mahaleb genotype selections.
Key words: Mahaleb, Dwarf rootstock, indole acetic acid (IAA), abscisic acid (ABA).