In vitro shoot proliferation rates of the rose cv. (hybrid tea) ‘Dr. Verhage’, as affected by apical dominance regulating substances

Abstract

The effects of three shoot tip pinching compounds incorporated into the nutrient medium and of the successive reculture technique on in vitro shoot proliferation of rose, cultivar ‘Dr. Verhage’, were studied. Of the three compounds tested, methyl ester of lauric acid (MELA) was the most effective followed, in declining order, by n-propyl-3-t-butylphenoxyacetate (M&B 25-105) and 2,3,5-triiodobenzoic acid (TIBA). MELA at 100 mg l −1 nearly quadrupled the proliferation rate of untipped microshoot explants, which was comparable to the tipped controls. Successive recultures of the basal clump of tissue remaining after the initial culture, on medium free of MELA resulted in a significant increase in the total number of new shoots, compared with the tipped controls. The other two compounds also promoted branching in untipped shoots but were less effective. The results showed that manual tipping of explants can be successfully substituted by chemical tipping, thus eliminating unnecessary handling of plant material under sterile conditions.