Development of Irrigation Control System in Response to Plant Water Stress in Tomato Hydroponics. (3). Irrigation Control Based on Evapolation Measurement by Evaporimeter.

Summary

This paper describes development and validation of an evaporimeter-based irrigation control system for hydroponically grown tomatoes designed to maintain moderate water stress and enhance fruit quality. The system uses a simple non-woven fabric evaporating disk and ultrasonic level sensor to measure evaporation rate and trigger irrigation events when cumulative evaporation exceeds a pre-set irrigation point. Under optimised irrigation points, the system successfully achieved >9% Brix tomatoes, with daily irrigation volumes showing strong correlation to cumulative evapotranspiration despite variability at early growth stages.

Regional applicability

This research is specific to controlled hydroponics technology and may have limited direct applicability to UK outdoor or soil-based tomato production systems. However, the evaporimeter methodology for demand-driven irrigation scheduling could inform water management strategy in UK protected horticulture and intensive vegetable systems, subject to validation under UK climate conditions.

Key measures

Evaporation rate (Ep), cumulative evaporation (ΣEp), irrigation point (IP), transpiration rate, photosynthetic photon flux density, Brix value, irrigation volume, cumulative evapotranspiration

Outcomes reported

The study evaluated the applicability of a simple evaporimeter device for automated irrigation control in hydroponically grown tomatoes under moderate water stress. Success was measured by achieving >9% Brix fruit when irrigation point was optimised, with irrigation volumes correlating strongly to cumulative evapotranspiration on a daily basis.

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