Breaking Bud Dormancy in Tea Crabapple [Malus hupehensis (Pamp.) Rehd.] with Cytokinins1

Abstract

A technique is described for forcing the buds of tea crabapple using cytokinins. Of the cytokinins tested, 6-benzylamino purine (BA) produced the best results at 2,000 ppm, 6-(benzylamino)-9-(2-tetrahydropyranyl)-9H-purine (PBA) was nearly as effective, and N6-[Δ2-isopentenyl]-adenosine (IPA) and N6-[Δ2 isopentenyl]-adenine (2ip) were ineffective. Depending on the cytokinin used, inclusion of 0.5 or 1.0% surfactant was required to insure consistent results. No differences were found among 8 surfactants tested. Dimethylsulfoxide (DMSO) was an excellent solvent for the cytokinins and slightly enhanced their effect. The treatment effect was not translocated from the site of application. This method was consistent, faster than 10 weeks of cold treatment, less phytotoxic than cytokinins applied in a lanolin fraction, and permitted rapid spray application of small quantities of solution.

The Role of Bud Scales in the Dormancy of Apples

“…The passage of temperate zone deciduous trees into and out of dormancy and rest generally is attributed to phytohormones, including both growth promoters and inhibitors (4,13,14,17,20,24,25). Correlations between rest intensity and inhibitor levels, particularly ABA, have been found, but ABA is not always effective in prolonging dormancy; nor are high ABA levels always required for deep rest (7,9,14,17,20,22,25).…”

Promoting Bud Development and Branching of Scotch Pine with 6-BA

“…Cytokinin applications have been shown to promote lateral bud growth and branching in woody species such as apple (2,6,10,12), Macadamia (1), Citrus (8), and rose (9). The authors hypothesized that some of the time and expense involved in shearing coniferous trees might be reduced with applications of cytokinins to the plants.…”

Effect of Some Growth Regulators and Nutritional Compounds as Substitutes for Chilling of ‘Delicious’ Apple Leaf and Flower Buds

“…The effectiveness of many compounds has been evaluated for their capacity to substitute for the chilling requirement of various crops. Among growth regulators, cytokinin has proven effective with apples (3,9,10), peaches (4), citrus (8), and crabapple (2). Gibberellins had no effect on breaking rest of apple buds or seeds (6,11) and peach flower buds (5), but it did stimulate the expansion of peach leaf buds (5).…”