A well-balanced ventilation strategy does more than control greenhouse temperature. This article explores the relationship between ventilation and plant evaporation, and how the right climate conditions can support the plant’s water balance, photosynthesis and light use efficiency.
Empower Plants through well-balanced ventilation
Optimise Plant behaviour
In the first article of this series, the concept of Growing by Plant Empowerment was introduced. Combining growers’ experience and knowledge of plant physiology, the goal of GPE is to optimise the behaviour of plants in the greenhouse environment by maintaining critical balances involving energy, water CO₂ and assimilates within the plant. These balances can be monitored by sensors, combined with crop measurements, then interpreted in the context of plant physiology and physics to help fine-tune and improve the crop.
Irrigation strategy
In the first article, the importance of a greenhouse’s irrigation strategy, in relation to the water balance of the plant, was explained. In this second article, we will explore the importance of GPE in a greenhouse’s ventilation strategy, focusing on the relationship between ventilation and plant evaporation, and eventually how a well-balanced ventilation strategy can promote photosynthesis and light use efficiency (LUE).
Well-balanced ventilation
Typically a ventilation strategy consists of a mixture of different methods. First, there may be a minimum window opening needed to avoid a build-up of adverse gases like NOx, ethylene etc. The release of moisture may be another reason to increase the angle of the window opening, which also depends on weather conditions. Typically, the main driver for large window openings is temperature control. It is often believed that temperature is the key to plant development, and temperatures that are too high must be avoided at all times.
Support the water balance
The ultimate goal of the ventilation strategy, however, should be to support the plant’s water balance and to ensure CO2 uptake for photosynthesis by keeping the stomata open under high radiation conditions. This maximizes LUE and production of assimilates for growth and development. Therefore, ventilation should be used to achieve the right combination of climate conditions, rather than simply reaching a specified temperature.
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