Stem‐cutting anatomy and biochemical responses associated with competence for adventitious root diferentiation in Acca sellowiana (Myrtaceae)

Abstract

Successful development of adventitious roots (AR) in cuttings imposes an important limitation to the propaga- tion of woody plants and in some species, the ability to form AR is strongly afected by genotype. However, we lack an

understanding of the diferences among genotypes underlying such diferent responses in various species. We examined the anatomical and biochemical efects of exogenous indol-3-butyric acid and type of cutting in rooting experiments of two Acca sellowiana genotypes with contrasting rooting ability. New meristems developed outside the cambial ring, without callus formation by day fourteen and new adventitious roots grew through the cortex emerging by day 28. Both anatomically

in vivo and biochemically in vitro, cuttings from the diferent genotypes behaved diferently. We found anatomical difer- ences between the genotypes that might explain the diferences in rooting ability. An earlier development of a periderm was

present in the difcult-to-root genotype. This secondary dermal tissue could be used as a reliable phase-change marker to distinguish juvenile from mature plant parts which have lost rooting capacity.