A MODEL OF THE EFFECTS OF TEMPERATURE AND TIME ON THE ACCEPTABILITY OF POTTED PLANTS STORED IN DARKNESS

The effects of six storage periods (1-21 days) and six constant temper atures (5-30 degrees C) were assessed in experiments on the acceptabil ity of twenty economically important potted plants (such as Azalea ind ica, Begonia x hybrida, Dendranthema grandiflora, Cyclamen persicum, D ieffenbachia 'Marianne', Dracaena fragrans, Euphorbia pulcherrima, Fic us benjamina, Saintpaulia ionantha, and Yucca aloifolia). A wide range of temperatures gave optimum storage (minimum quality loss) when the plants were stored for a relatively short time, but a progressively sm aller range as the products were stored longer. The results were used to devise a model describing the effects of temperature and time on th e acceptability of the potted plants by the buyer. All plants were sen sitive to high temperature induced deterioration and most plants were sensitive to chilling. The apparent rate of decrease in the percentage of acceptable plants in time was therefore described as a sum of two separate reaction rates, both dependent on temperature according to Ar rhenius' law. Application of nonlinear regression techniques allowed a nalysis of the data in their entirety using one model formulation for all species tested. Except for Euphorbia (87%) and Philodendron (88%), the explained variance (R(adj)(2)) exceeded 90% for all species and w as more than 95% for eight species, which implies that the present gen eric approach is feasible. The model was converted into a dynamic form ulation by applying partial differentiation with respect to time. The dynamic formulation allows calculation of the effect of temperature ch anges during storage and transport.