Shoot elongation retardation owing to daminozide in chrysanthemum: I. Modeling single applications

Abstract

Two mathematical models were developed to simulate shoot elongation of chrysanthemum ( Dendranthema × grandiflora (Ramat.) Kitamura) in response to single applications of daminozide at various concentrations. Both models use a modified Richards function to predict the daily increment in shoot growth of the top shoot on pinched plants. The decline in time of the growth retardation effect was described by using a linear and an exponential function. When fitted to collected data, no significant difference was recorded in the accuracy with which the two models represented the daminozide effect on shoot growth. The initial elongation rate inhibition was found to vary with growth regulator concentration. The persistence of the daminozide effect on shoot elongation was found to be approximately 34±1.2 days. In validation trials both models showed a slight tendency of over-estimating shoot elongation of retarded plants with R 2 values ranging from 0.9966 to 0.9996 depending on the treatment studied. The results also showed that the models could be used to simulate the daminozide effect at different times of application. The use of the models as prediction tools is discussed.