Modellling visual product quality in cut chrysanthemum

Throughout the year, cut chrysanthemum growers aim at a constant product quality by varying plant density, duration of the long-day (LD) period and, more recently, by the use of supplementary assimilation light during periods of poor natural light conditions. Visual quality of cut chrysanthemum is mainly determined by plant mass (in relation to stem length), number of flowers per plant and flower size. For production in agreement with market demands at the lowest costs, models can be of great interest. We developed and validated an explanatory photosynthesis-driven crop growth model, that can predict influence of planting date, plant density, CO2 concentration and supplementary assimilation light on visual quality of cut chrysanthemum. The model is presented and some validation results are given. It is shown how the model can be used to define acceptable plant densities throughout the year at different levels of assimilation light intensities or glasshouse light transmissivities. Also the trade-off between duration of the LD period and plant density, when aiming at a certain plant mass, is quantified using the model