Herbaceous Peony in Warm Climate: Modelling Stem Elongation and Growers Profit Responses to Dormancy Conditions

Abstract

We analyzed data collected for the herbaceous peony cultivated in a warm climate region and stored in winter under three chilling constant temperatures. We used quadratic regression to model stem elongation responses to winter dormancy conditions, and the logistic function to model the weekly stems elongation. The predicted maximum stem length from the first model was used as the input parameter for the second model. More than 4,000 data for various: 1) chilling constant temperatures during the dormancy, 2) dormancy duration, and 3) germination duration were used. The models were applied to determine the optimal amount of chill units. For this purpose, two criteria were used in different versions of modelling: the maximal stem length and the maximum profit of growers. For the two chilling temperatures, 2° C and 6° C, the results were very close one to another for the first criterion and significantly different for the second one. For the third chilling temperature of 10° C the model failed to determine the optimal amount of chill units. The inverse confidence interval method for statistical testing of the optimal amount of chill units was used.