The Effect of Some Monohydroxybenzoic and Dihydroxybenzoic Acids as Auxin Synergists on Rooting Softwood Cuttings of Basswood (Tiliaamericana L.) Under Mist
Softwood cuttings of one clone and one juvenile population of basswood were rooted under intermittent mist, using a 2-min basal dip of indolebutyric acid (IBA) at concentrations of 1000, 5000, and 10 000 parts per million (ppm) in combination with one of salicylic acid, p-hydroxybenzoic acid, 3,5-, 2,5-, and 2,6-dihydroxybenzoic acids at concentrations of 5, 50, and 100 ppm. None of the phenolic compounds showed any root-promoting effect when used singly. In combination with IBA, 2,5-dihydroxybenzoic acid showed a root-promoting effect when applied to cuttings of the population but not for cuttings of the single clone.A root-promoting effect at certain of the higher concentrations of the rest of the phenols when combined with IBA could not clearly be distinguished from sample variation. IBA alone or in combination with any of the phenols had a much smaller root-promoting effect when applied to the cuttings of the single clone.