Managing irrigation during high light conditions is crucial for maintaining healthy plants and achieving optimal crop yields. High light intensities increase water demand, requiring growers to fine-tune their irrigation strategies to meet the needs of their plants. Alessandro Montanarella, consultant at Cultilene, shares his advice on how to optimize water management during these challenging conditions.

Understanding high light conditions

High light conditions, such as those experienced during summer in regions like Italy, significantly impact water requirements. On a sunny day, light intensity can reach 3,000 joules per square centimetre.With each tomato plant requiring approximately 1 cc of water per joule, this translates to about 3 litres of water per plant daily. Meeting these demands requires precise irrigation management.

Irrigation based on outside light levels

To ensure plants receive water exactly when they need it, irrigation schedules should be linked to light intensity rather than fixed intervals. There are several benefits of using software that measures the light intensity and activates irrigation systems automatically. For instance:

• Set irrigation to start every 100-200 joules of accumulated light. Number of joules should to take in account the calculated optimal dose size (ODS).
• Provide a precise volume of water per irrigation, suitable with the calculated ODS.

This approach prevents overwatering on cloudy days and under-irrigation on sunny days, maintaining an optimal water balance for plant health.

Balancing plant growth

If not managed properly, high light conditions can stress plants. As a direct response to the perceived ‘danger’, they shift their energy towards producing flowers and fruits prematurely. 

On the other hand, each irrigation event has a vegetative impact on plants, providing comfort and promoting growth. While this is necessary, too much vegetative growth can halt productivity of the plant.

By carefully controlling water supply, you can encourage balanced growth that supports both foliage development and fruit production.

Managing water temperature

Water temperature is another factor that plays a critical role in plant health during high light conditions. Warmer water holds less dissolved oxygen, creating an environment conducive to diseases like Fusarium. 

To mitigate this risk, you can consider using white pipes instead of black ones to reduce water temperature.Another solution is to position irrigation pipes in shaded areas within the greenhouse. This way, you can make sure water temperature remains below 27-28°C to maintain adequate oxygen levels.

Higher plant density

In countries that are dealing with high light conditions regularly and for longer periods during the year, there is another solution to create a cooling effect: increasing plant density in the greenhouse. This can create a microclimate that reduces exposure to excessive light and heat, making it easier to deal with the light intensity. 

Tips for high light irrigation

So, whether you are facing high light conditions a few days a year of throughout a full season, it will always remain a challenge. These tips can help to prevent plant stress and maximize yields.

• Link irrigation to light intensity:use automated systems to adjust water supply based on accumulated light levels.
• Control water temperature:implement measures to keep water cool and oxygenated.
• Adapt plant density:increase planting density to create a more favourable microclimate under high light conditions.

Start optimizing your irrigation today

By tailoring your irrigation practices to high light conditions, you can support healthy plant growth and optimize yields.

The information provided by Saint-Gobain Cultilene has been compiled with great care and is intended solely as a guideline for the user. Saint-Gobain Cultilene therefore cannot guarantee any errors and no rights may be derived from the information or advice provided. The user himself is responsible for checking the accuracy and suitability of the information and advice for application. No commercial use may be made of the information and advice provided by Saint-Gobain Cultilene, in whole or in part, without the written consent of Saint-Gobain Cultilene.