Nonlinear models to describe height and diameter of sugarcane RB92579 variety¹

Modelos não lineares na descrição da estatura e diâmetro da cana-de-açúcar variedade RB92579

ABSTRACT

Brazil is the world’s largest sugarcane producer (Saccharum spp.), followed by India and China. In 2019, Brazil produced 642.7 million tons of sugarcane, having collected 1.44 billion and 983.52 million dollars from sugar and ethanol exports, respectively. For crop management, it is important to monitor plant growth, duration of growth phases and point of physiological maturation. The aim of this study was to evaluate the fit of nonlinear Logistic, Gompertz, Brody and von Bertalanffy models to the height and diameter growth of ratoon cane stalk RB92579 variety, considering age in days. The parameters of models were estimated using R software routines, applying the least squares method and the iterative Gauss-Newton process. The adjustment of models was compared using the following evaluators: determination coefficient (R²), residual standard deviation (RSD) and corrected Akaike information criterion (AICc). In all models, parameters were significant by the t test at 1% level, except for the Brody model. When using the Shapiro-Wilk, Durbin-Watson and Breusch-Pagan tests, it was found that residues were normal, homoscedastic and independent at 1% significance level. All models fitted well to data, except for the Brody model for stalk height. Based on results, the Gompertz and Logistic models presented higher R² values and lower RSD and AICc values; thus, it could be concluded that these models are suitable to describe the height and diameter of sugarcane RB92579 cultivar, respectively.

Key words:
Growth curves; Logistic; Gompertz