Determination o leaf area of potted chrysanthemum associated with the accumulation of degree-days

Abstract

Chrysanthemum is a species of great importance in the flower market due to characteristics such as diversity in shape, color and size of inflorescences and rapid growth cycle. To better define and characterize its production process, this study aimed to establish mathematical models to describe the leaf growth of chrysanthemum (Dendranthema grandiflora) ‘Rage’ in function of the growing degree-days accumulation. Twelve experiments were performed with cuttings being planted and grown in plastic pots (14 cm) containing substrate and submitted to fertigation. The experimental design was complete randomized blocks with five replicates. Each useful plot consisted of three plants, totaling 15 plants per assessment. Weekly, the leaf number and leaf area were assessed, in a total of ten destructive assessments. Four models were developed to describe the relationship between leaf growth and GDD accumulation in chrysanthemum ‘Rage’ grown in greenhouse without climate control. Mathematical models have been validated and can be used in chrysanthemum to relate leaf area and growing degree-days. The models showed RMSE of 88.0 cm2 (summer), 29.44 cm2 (fall), 55.61 cm2 (winter) and 80.01 cm2 (spring).