Root Initiation in Cuttings of Pinus radiata Seedlings: Effects of Aromatic Amino Acids and Simple Phenylpropanoids

Abstract

In the formation of adventitious root primordia from hypocotyl cuttings of Pinus radiata, the effects of aromatic amino acids and simple phenylpropanoids depended on the response of the cuttings to indolebutyric acid (IBA) alone and on the stage of initiation of the primordia. When rooting by the IBA controls was low, phenylalanine, tyrosine, chlorogenic acid, and ferulic acid, in the presence of IBA, stimulated rooting. These compounds were most effective when applied during the initiative phase and, with the exception of tyrosine, were ineffective during the pre- and postinitiative phases. When rooting of the IBA controls was high, these compounds were generally ineffective or even inhibitory. These data indicate that phenolic substances play a role in root primordium formation.