ROOT-FORMATION IN CUTTINGS OF APPLE IN RELATION TO AUXIN APPLICATION AND TO ETIOLATION

The inter‐relationship of auxin treatment and etiolation, in their effect on adventitious root formation, was investigated in stem cuttings of the difficult‐to‐root cultivar of apple ‘Bramley's Seedling’. Unetiolated cuttings of the scion variety rooted at a comparatively low level with a range of concentrations of each of six synthetic hormones. Localized etiolation of the shoot, on the other hand, stimulated root formation in proportion to the length of the stem segment treated. Indole butryric acid applied to etiolated cuttings promoted a comparatively small, but still significant, increase in root formation. The effect of etiolation is attributed to a change in the effective level of an active factor, as opposed to a direct stimulation of its synthesis. Copyright © 1979, Wiley Blackwell. All rights reserved