VPD, Vapour Pressure Deficit, is the indicator of the "air-water" ratio in the greenhouse environment. Controlling it accurately means avoiding diseases, water stress and crop growth problems. This would require the ability to manage a whole range of farm systems precisely and simultaneously. A dream that, with GREEN LOGIX, becomes a reality.

Drip irrigation, misting, drenching, adjustment of the irrigation according to the atmosphere of the greenhouse over the hours... These are part of the actions to fine-tune the VPD. This monitoring is very difficult, if not impossible manually, especially in several greenhouses. GREEN LOGIX makes this possible, and it is one of the reasons for our innovation.

It is now possible to fine-tune all the parameters of the VPD!

Irrigation, ventilation, alerts, surface management, must be under control and adjusted throughout the day to accommodate fluctuations in VPD. This is the key to maintaining a balance between temperature and humidity and thus promoting healthy plant growth in greenhouses. This is exactly what our GREEN LOGIX solution allows: we connect all the devices (irrigation network, sunroofs, foggers, pumps, etc.) that you can control from an interface that we wanted to be simple and reliable, accessible from your computer, tablet, laptop. And all this while adapting to the existing system: sensors, PLCs, motors, etc.

Vapour Pressure Deficit (VPD), a key to crop health

The Vapour Pressure Deficit (VPD) is the difference between the maximum amount of water that the air can hold (at saturation) and the amount of water it actually contains. 

If VPD is too low (less than 0.4 kPa), the air is almost saturated with water: in this case, the crops cannot transpire effectively, which promotes the development of fungal diseases.

If the VPD is too high (above 1.0 kPa), the air is too dry: this leads to rapid transpiration of the leaves, even water stress and reduced CO2 absorption.

Irrigation accuracy: the key factor

To control the vapor pressure deficit (VPD) in a greenhouse, irrigation plays a crucial role. Here are some steps to best manage it and maintain optimal VPD:

• Monitor VPD: Before planning irrigation, measure VPD in your greenhouse regularly. This helps to understand the balance between air humidity and temperature 

• Adapt irrigation according to VPD.

Irrigation Precision: Methods, Tools

Drip irrigation: This method allows precise control of the amount of water supplied to the plants. 

Misting/drenching: Misting can increase the relative humidity of the air, which can reduce VPD. However, use with caution to avoid excessive humidity.

Finally, irrigation should be avoided during hot hours: irrigation during hot weather can increase VPD. The quality of the water is also to be taken into account: impurities can affect the health of the plants and influence the VPD.

Two advantages to be exploited: precise measurement tools and automation

Managing a parameter as sensitive as VPD is not easy. Fortunately, new technologies can prove to be valuable allies.

An example of this is the digital thermohygrometer, which regularly measures the temperature inside the greenhouse, but also outside. This makes it possible to track the variations and adjust the temperature accordingly. 

Our GREEN LOGIX solution is also a key asset: it allows you to connect all the means at your disposal: air conditioners, heating and ventilation equipment, sunroofs, irrigation network, pumps, etc.

Specified measures related to this automation allow you to automatically manage VPD for optimal health and yield of your plants.

With GREEN LOGIX, you can increase your decision-making power tenfold!

The fine-grained control of the DPV is therefore one of the many advantages of GREEN LOGIX. One of the meanings of our innovation is to increase the farmer's decision-making power: reduction of the water bill, the electricity bill, the number of trips to the farm, simplified monitoring of indicators with the possibility of printing reports (and therefore a saving in administrative work)... The field of possibilities is huge, and you define it! Curious to dig deeper into the subject? Contact us!

To go further

The table of Vapour Pressure Deficit (VPD) values below shows how accurate the data are for vegetable plants in greenhouses or grow rooms.