Evaluation of the effect of temperature on a stem elongation model of Phalaenopsis

Abstract

Phalaenopsis orchid has become one of the most important potted plants in flower markets. However, the timing at which flowers reach the saleable stage can be very important since the demand may be larger for specific holidays. The regulation of stem growth could serve as an opportunity for regulation of flowering. The purpose of this study was to evaluate the effect of temperature on stem elongation. In this study, a stem elongation model established by a statistical technique was used to evaluate the effect of temperature. The stem lengths of four named Phalaenopsi varieties and 15 unnamed Phalaenopsi hybrids were measured under different temperature regimes. The three parameters of the logistic growth model, the maximum stem length, growth rate, and inflection point at which the growth rate reached a maximum value were estimated by using nonlinear regression analysis. Then, the differences among varieties in these three parameters were assessed by categorical testing. The results of this study indicated that stem growth rate was positively affected only by day temperature. The maximum stem length was negatively affected by the day temperature and positively influenced by the temperature difference between day and night. The results of this study could provide a practical method to regulate stem elongation by adjusting the temperatures, thus helping growers time the flowering of their potted orchids to meet market demand.