Rapid Production Methods for Ottawa-3 Rootstock and Branched Apple Nursery Stock

Abstract

A system for the rapid production of Ottawa-3 (0.3) rootstock (Malus domestica Borkh.) and branched apple nursery stock in the greenhouse is described. The time required for production of a finished' tree, ≈1 year, compared favorably with traditional methods. Cuttings derived from tissue-cultured 0.3 rootstocks rooted well (up to 94% success rate), and the rooting effect persisted in cuttings from tissuecultured rootstocks grown for 1 year in the field. All combinations of two levels of N and P in a Long Ashton nutrient solution were applied weekly to pots containing either tissue-cultured rootstocks or cuttings. The growth rate of tissue-cultured rootstocks exceeded that of cuttings. The growth rate of both sources of rootstocks increased in response to added P and N. Growth of scion shoots (`Royal Gala') increased in response to N. Branch production of `Royal Gala' was greater for trees with the higher P and N rates. Trees on tissue-cultured rootstocks had more branches than those on cuttingderived roostocks at the higher level of N.