Stomatal resistance of New Guinea Impatiens pot plants. Part 1: Model development for well watered plants based on design of experiments

•A new method based on Full Factorial Design to model stomatal resistance is proposed.•FFD was implemented from data recorded with a porometer in a growth chamber.•FFD was validated against data collected from an ornamental crop inside a greenhouse.•Global radiation and humidity play a major role in stomatal resistance.•The FFD model showed better performance to predict Rs than the Jarvis model.

In greenhouses, reducing water consumption by increasing water efficiency in order to fulfil the requirements of sustainability is a challenge. To reach this goal, we need to better understand the water demand of plants. Transpiration is the main mechanism involved in water transfer, which is controlled by stomatal resistance Rs. Predictive models can be used to assess this parameter. However, few models currently exist for greenhouse plants grown in pots. The aim of this work is to develop a model of Rs based on full factorial design (FFD), and to validate it for greenhouse plants at various growth stages.FFD is based on an optimisation process to establish a polynomial relationship between Rs and radiation, humidity, and temperature. To establish the parameters of the model, a set of experiments was conducted inside a 10-m2 growth chamber with New Guinea Impatiens grown in pots. Rs was measured with a porometer under nine climatic scenarios. Once the parameters were determined, the FFD model was validated against experimental data recorded from a greenhouse Impatiens crop, and compared with the Jarvis model. The slopes of the linear regression between measured Rs values and Rs values predicted from the FFD and Jarvis models varied within the range 0.89–1.12 for FFD and 0.45–0.54 for Jarvis.FFD was therefore able to correctly simulate Rs. Its main advantage was to only require few data for its calibration, contrary to the Jarvis model. In a next step, it will be used to predict transpiration rates.