Quantifying the effects of water on growth dynamics of standard cut chrysanthemum in solar greenhouse

Photosynthesis and dry matter production are essential for guaranteeing the external quality of ornamental plants. Water is the important factor affecting plant photosynthesis and dry matter production. The aim of this study was to quantitatively investigate the effects of water on photosynthesis and dry matter production of standard cut chrysanthemum grown in a solar greenhouse. Experiments of standard cut chrysanthemum (Chrysanthemum morifolium. ‘Shenma’) with different planting dates and different levels of water treatment were conducted in a solar greenhouse in Beijing from August 2006 to June 2007. The integrated photo-thermal index, the product of thermal effectiveness, PAR and day length (PTEP), was used to describe the seasonal change of the canopy leaf area index. Effects of substrate water potential on the dynamics of leaf photosynthesis rate and the canopy leaf area index were quantified based on the experimental data. These quantitative relationships were then integrated into a photosynthetically driven dry matter production model to predict the effects of substrate water potential on dry matter production of standard cut chrysanthemum in solar greenhouse. Independent experimental data were used to validate the model. The results showed that the coefficient of determination (R2) between the simulated and the measured values of canopy leaf area index, the maximal leaf gross photosynthesis rate and the dry matter production based on the 1:1 line were 0.94, 0.90, 0.94, respectively; and the relative prediction errors (RE) between the simulated and the measured values were 11.95%, 3.13%, 11.14%, respectively, for the canopy leaf area index, the maximal leaf gross photosynthesis rate and the dry matter production. The model developed in this study gives satisfactory predictions of the canopy leaf area index, the maximal leaf gross photosynthesis rate and the dry matter production of the standard cut chrysanthemum, hence, can be used for optimizing water management for standard cut chrysanthemum production in solar greenhouses.