Predicting External Quality Traits from Organ Dry Weight in Cut Chrysanthemum (Chrysanthemum morifolium)

The integration of functional and structural crop models can be valuable for examining how physiology and morphology interact in determining plant processes. The output of functional crop growth models, however, is organ dry weight which cannot be used directly as input for structural models. The aim of this study was to quantify the relationships between organ dry weight and morphological (external quality) traits of plants so as to bridge the functional and structural crop growth models. Using chrysanthemum (Chrysanthemum morifolium 'Jinba') as a case study, four experiments with different planting dates were conducted in a lean-to type greenhouse from 2006 to 2008. Plant height, number of green leaves per plant and flower-head diameter was, respectively, determined as a function of organ dry weight and stem diameter was determined as a function of plant height. Independent experimental data were used to validate the model. The results show that the model developed in this study can predict the external quality traits of chrysanthemum plants satisfactory. The coefficient of determination between the predicted and measured data was 0.99 for plant height, 0.94 for number of green leaves per plant, 0.99 for flower-head diameter and 0.80 for stem diameter. Further evaluation is needed when applying this model to a wider range of variety and environment.