Horticultural Science and Technology ISSN:1226-8763(Print) 2465-8588(Online) 원예과학기술지

The purpose of this research was to find the best model (in term of goodness of fit) among Gompertz, Logistic and Richards growth models for the variation in plant height of standard cut chrysanthemum plants at different planting dates with different long-day periods. The measured plant height with time was well described by a simple sigmoidal model with a higher R² (>0.97) than that of non-linear regression models. The estimated parameters of the simple sigmoidal model were easier to interpret; they were relative growth rate, maximum plant height, and the number of days after planting to reach the maximum stem elongation rate. The derivative of these models could be used to calculate the absolute stem elongation rate with time, which tended to follow a bell-shaped curve for Gompertz, Logistic, and Richards growth functions. However, the function without an intercept showed large variations in standardized residuals and bias against the predicted value even though it had a high R² value. The model with an intercept showed highly stable standardized residuals and normality with the three growth functions. Based on the homogeneity of standardized tests and the values of Skewness and Kurtosis as well as the non-significance probability of Kolmogorov-Smirnov and Shapiro-Wilk, the Gompertz growth model with an intercept was a highly suitable function for the estimation of measured plant height of standard cut chrysanthemum ‘Baekma’. This model summarized biological parameters well, such as the dynamics of stem elongation rate and days after planting to reach the maximum growth rate with different planting dates, compared with the other sigmoidal growth models.