Mature cladodes of prickly-pear cactus (Opuntia amyclaea Tenore. `Reina') were treated with five wounding methods and four concentrations of potassium salt indole-3-butyric acid (K-IBA) to stimulate adventitious root formation. The wounding method and K-IBA had highly significant effects on root number and root dry mass of cladodes. Interaction between K-IBA and wounding methods showed that greater root number was obtained at the higher auxin concentrations and with wounding methods that had the greatest cut surface area. K-IBA concentrations from 4,144 to 41,442 μm (1,000 to 10,000 mg·L-1) increased root dry mass. Only the wounding method affected rotting of cladodes. Treatments allowing suberization had a higher percentage of nonrotted cladodes. This research validates the commercial practice of allowing cladodes to suberize early in the propagation cycle. K-IBA altered rooting polarity and stimulated adventitious root formation along the wounded cladode surfaces. The vertical nonsuberized wounding methods and auxin treatments are an excellent classroom demonstration for manipulating rooting polarity. Auxin application and wounding could be of commercial benefit for enhanced rooting in the clonal regeneration of new selections for prickly-pear cactus orchards.
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