Stubborn is a clonal rootstock for stone fruits (Prunus L.), developed by the Federal Research Center for All-Russian Genetic Resources of Plants named after N.I. Vavilov. It is intended for grafting of apricot, domestic and Chinese plum, ensuring stable tree development in various climatic conditions.
The rootstock is characterized by dwarf growth: shoots of medium length, straight, non-branching, round and hairless. Buds are small and reflexed, leaves are of medium size, oblong, short-tapered, light green, wrinkled, matte with coarse venation. The upper part of the leaf is slightly hairy, flat, and the edges are finely saw-toothed. The petiole is long, of medium thickness and hairy. Meanwhile, the survival rate of cuttings is high – 98-100%, and rooting is 87-93%. The rootstock does not form root suckers and is resistant to winter root injury.
Stubborn's resistance to climatic stresses is at a medium level: it withstands moderate drought, heat load and is winter hardy. The disease clasterosporiosis affects it in a very weak degree, which makes this rootstock a reliable choice for horticulture where resistance to common pathogens is required.
