Contributions of the leaves and axillary shoots to rooting inEucalyptus granáisHill ex Maid, stem cuttings

Abstract

In one-node stem cuttings of Eucalyptus granais the absence of leaves was fatal. The optimum leaf area per leaf for rooting was 2-5 cm2, and in this range rooting was higher in one-leaf than in two-leaf cuttings. Axillary shoots started to develop soon after the cuttings were set and their growth was promoted by the presence of the subtending leaf. Thus, in one-leaf cuttings the shoot in the leafy axil grew, at the expense of the shoot in the defoliated axil, while in two-leaf cuttings the shoot in the upper (sub-opposite) axil tended to grow more quickly. Axillary shoots were also vigorous in cuttings from decapitated and disbudded mother plants. Rapid shoot growth was associated with low rates of abscission of the subtending leaf and relatively high rooting ability. Removing axillary shoots from cuttings accelerated leaf abscission and reduced rooting. The stem of the cutting often swelled and discoloured from the base, apparently due to the demand of the cutting for water. Additional leaf wounds had no...