Balancing plants under high temperatures and intense light
May often brings extreme conditions for tomato growers: high temperatures combined with intense light radiation. These factors exert a strong generative pressure on plants, which at first glance might seem beneficial—after all, many strategies aim to stimulate flowering and fruit set. However, when these conditions persist, they can disrupt plant balance and compromise production and quality. Physiological disorders like BER, wrong fruit setting and poor pollination are some of the most common problems in case of a bad control of the plant balance.

Growers in typically warm regions such as Southern Europe (Italy, Greece, Spain) are most exposed to these challenges, but in recent years, similar extremes have occurred even in traditionally cooler areas like Eastern Europe. The key to success? Maintaining a perfect vegetative-generative (V-G) balance through precise irrigation, climate control, and crop management.

The risks of persistent generative pressure
Under prolonged heat and high radiation, plants tend to become overly generative. This can lead to:

• Reduced leaf area and canopy density.
• Poor fruit development and uneven truss quality.
• Increased stress on the root system.

To counteract these effects, growers must adopt strategies that restore balance and protect plant health. Important to understand is that if the climate change, if the varieties are changing the growing strategy has to change as well. Talking about plant density the interesting part is to find the magic number for that variety, that area and the available technology.

Irrigation: consistency is key
Tomato plants under these conditions can consume up to 3 liters of water per day. A well-designed irrigation strategy ensures:

• Stable water content in the substrate to prevent excessive dry-back.
• Stable EC levels at the dripper and in the slab to avoid additional generative stress.
• Night cycles when necessary to maintain root activity without stimulating the plant.

A substrate with high water retention capacity plays a crucial role here. It provides a more vegetative influence, helping plants cope with generative pressure by ensuring consistent water and nutrient availability.

Can we use the net evapotranspiration as an indicator of the plant activity? For sure more water is “travelling” through the plants more biomass will be produced. The key is to keep the plant active. When extreme conditions persist, the plant goes in a kind of “protection mode”, reducing the LAI to reduce the loss of water. This protect the plant but negatively impact on the yield.

Plant density: creating a vegetative environment
Increasing the number of heads per square meter helps create a more vegetative microclimate. A denser canopy:

• Reduces direct radiation on individual plants.
• Maintains better humidity levels.
• Mitigates the generative impact of extreme conditions.

Shading: reducing incident radiation
Strategic shading is another effective tool to protect plants from excessive light and heat. By lowering radiation levels:

• Leaf temperature decreases.
• Transpiration stress is reduced.
• The risk of physiological disorders (such as blossom-end rot) is minimized.

Cultilene solutions
Cultilene supports growers facing these challenges with:

• Slabs with high water retention and cubes for optimal control water content.
• Technical guidance on irrigation and EC management.
• Data-driven strategies to adapt cultivation to extreme conditions.

Many growers, with Cultilene’s support, have successfully transformed heat waves into productive periods by combining these solutions with precise crop steering.

Turning challenges into opportunities
Extreme conditions don’t have to mean reduced performance. By focusing on irrigation precision, canopy management, and substrate choice, growers can maintain plant balance and achieve the ultimate goal of cultivation: high production and excellent fruit quality.

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.