Modelling the effects of soil water potential on growth and quality of cut chrysanthemum (Chrysanthemum morifolium)

A complete dynamic model was developed to describe the effects of soil water potential (WP) on the growth and external quality of standard cut chrysanthemum (Chrysanthemum morifolium) in order to optimise water management of greenhouse crops. Experiments using chrysanthemum cv. ‘Jinba’ with different planting dates and levels of water treatment were conducted in a lean-to type greenhouse from 2006 to 2008. The dynamics of leaf area index (LAI), dry matter partitioning, and external quality traits (plant height, number of leaves per plant, flower-head diameter and peduncle length) were first determined as functions of accumulated photothermal index (PTI). Impacts of WP on leaf photosynthetic rate, LAI, dry matter partitioning, and the external quality traits were quantified via introducing the experimentally identified effects of WP on the parameters in the light response curve of leaf photosynthetic rate and the PTI-based functions. These quantitative relationships were incorporated into a generic crop growth model SUCROS. Using independent experimental data, the model was found to give good predictions for biomass production, dry weight of organs, and the external quality traits of the chrysanthemum cultivar grown under different levels of water supply. The coefficient of determination (r2) between the predicted and measured results was 0.91 for LAI, 0.88 for biomass production, and varied between 0.83 and 0.93 for organ dry weight and the external quality traits. Further evaluation is needed when applying this model to a wider range.