Improvement of irrigation and sanitary risk control in a cucumber greenhouse crop using vapour pressure deficit and fruit temperature sensor

摘要

Cucumber crops under heated greenhouses represent 72% of the total surface areas in France. Decision-support modelling tools have to be provided and adapted for growers to increase efficiency of climatic and irrigation parameters in greenhouse. Usingphysiological investigation and innovative tools, we proposed to improve cucumber crop management in the North-West of France by on-line control of irrigation and dehumidification techniques. In order to improve water use efficiency of cucumber crop in greenhouse, decision making tools including vapor pressure deficit (VPD) analysis has been studied. The aim is to manage irrigation triggering not only by the amount of radiation perceived by the greenhouse (usual practice), but also by the estimated transpiration rate of a cucumber crop. Transpiration rate could be appreciated through the calculation of VPDieaf-air, deriving from leaf temperature measurements using infra-red sensor, temperature of the greenhouse and air humidity. A threshold of irrigation triggering has been proposed for cucumber crops in a commercial greenhouse in the North-West of France. In a second experiment, the use of infra-red sensor in association with fruit transpiration modeling is proposed to monitor fruit temperature during crucial day periods of time when dehumidification must be required to protect plant from condensation. This technique is essential in heated greenhouse due to sanitary risks (Dydimella bryoniae, Sphaerotheca fuliginea, etc.) associated with the presence of free water at the surface of plant organs, notably fruits, as it could largely affect yield and fruit quality. Dehumidification could be driven by fruit temperature.