A quantitative description of inhibition of stem growth in vegetative lateral shoots of Chrysanthemum morifolium by N-dimethylaminosuccinamic acid (daminozide).

The concentration of N-dimethylaminosuccinamic acid (daminozide) in four lateral shoot fractions of vegetative plants of chrysanthemum morifolium cv. Bright Golden Anne was determined at intervals over twenty three days following 0.2%, 0.6% and 1.5% foliar spray applications of this growth retardant. The decrease in daminozide concentration in stem tissue conformed to first order kinetics, but in leaf fractions did not follow any simple pattern.Inhibition by daminozide of lateral shoot growth was wholly attributable to its effect on the stem. A mathematical treatment, based on an approach originally developed to describe inhibition of bacterial growth, describes the relationship between daminozide concentration in the stem and inhibition of growth in stem mass. The results quantitatively describe the phenomenon of "growing out" which is frequently observed in daminozide-treated plants, and suggest that daminozide exerts its primary effect at a site located in the stem.