Abstract:

【Objective】 The aim of this study was to quantitatively investigate the effects of nitrogen on external quality of solar greenhouse standard cutting chrysanthemum, and to optimise the nitrogen management for standard cutting chrysanthemum production in solar greenhouse. 【Method】 Experiments with different planting date and nitrogen treatment were conducted in a solar greenhouse in Beijing during 2005 and 2006. The cultivar used in the experiments was Dendranthema morifolium ‘Shenma’. The integrated photo-thermal index, the product of thermal effectiveness, PAR and day length (PTEP), was used to describe the changes of the external quality indices (plant height, stem diameter, leaf number, diameter of flower head, length of flower neck). Effects of the accumulated leaf nitrogen content at flower bud showing stage on the dynamics of the quality indices were quantified based on the experimental data. Based on these quantitative relationships, a model for predicting the effects of nitrogen on external quality of standard cutting chrysanthemum in solar greenhouse was developed. Independent experimental data were used to validate the model. 【Result】 In the range of nitrogen available in the soil during the experimental seasons, the effect of nitrogen on plant height and leaf number were not significant. The coefficient of determination (R2) between the simulated and measured value of plant height, stem diameter, leaf number, diameter of flower head and length of flower neck of the standard cutting chrysanthemum plants were 0.99, 0.96, 0.96, 0.97, 0.98, respectively; and the relative prediction error (RSE) were 5.25%, 3.04%, 8.9%, 10.92%, 9.22%, respectively based on the 1﹕1 line. 【Conclusion】 The model developed in this study can be used for the optimization of nitrogen management for solar greenhouse standard cutting chrysanthemum ‘Shenma’ production.

Key words: standard cutting chrysanthemum, solar greenhouse, leaf nitrogen content, external quality, model