Heat Stress | OMEX Agrifluids

The Challenge

High temperatures are becoming an increasing challenge for growers worldwide. Heat stress occurs when temperatures rise above the optimum range for plant growth, affecting crop development, yield potential and quality.

The impact of heat stress depends on the crop, growth stage, duration of exposure and environmental conditions such as water availability and humidity. Short periods of extreme heat can affect sensitive stages such as flowering and fruit development, while prolonged high temperatures can significantly reduce overall plant performance.

How Heat Stress Affects the Plant

Plants rely on a balance between photosynthesis, respiration and water regulation to maintain healthy growth. During periods of excessive heat, this balance is disrupted.

High temperatures can:

Reduce photosynthetic efficiency by affecting enzyme activity and limiting carbon dioxide uptake.
Increase respiration rates, causing plants to use more stored energy.
Increase transpiration, resulting in greater water loss from leaves.
Trigger stomatal closure as plants attempt to conserve water, further reducing photosynthesis.
Disrupt reproductive processes, including pollen development, fertilisation and fruit set.
When heat stress persists, plants prioritise survival rather than growth, reducing yield potential and impacting crop quality.

How Heat Stress Affects Nutrient Uptake

Heat stress often occurs alongside reduced soil moisture, creating additional challenges for nutrient availability.

As soil dries, root growth and activity can decline, reducing the plant’s ability to take up essential nutrients. Nutrients that rely on water movement through the plant, such as calcium, can become less available to developing tissues.

High temperatures can also increase nutrient demand as plants work harder to maintain normal physiological processes.

What to Look For

Vegetative Symptoms

Wilting during the hottest part of the day
Leaf rolling or curling
Leaf scorch or burnt leaf margins
Reduced plant growth
Premature leaf ageing and senescence

Reproductive Symptoms

Flower abortion
Poor pollination and fruit set
Reduced fruit or grain size
Uneven crop development
Lower overall yield potential

Nutritional Support for Heat Stress

Maintaining balanced nutrition helps plants continue important physiological processes during periods of heat stress.

Potassium

Potassium plays a key role in water regulation, stomatal control and maintaining cell function. Adequate potassium nutrition helps plants manage water use and supports photosynthesis during periods of environmental stress.

Calcium

Calcium is essential for strong cell walls and healthy plant structure. During heat stress, calcium movement can become limited, affecting rapidly growing tissues and developing fruit.

Magnesium

Magnesium is central to chlorophyll production and photosynthesis. Maintaining magnesium levels supports energy production and plant growth during challenging conditions.

Micronutrients

Micronutrients such as boron, zinc and manganese support enzyme activity, flowering and reproductive development.

Biostimulants

Biostimulants can support natural plant processes involved in stress response and recovery.

When Foliar Nutrition Can Help

During periods of heat stress, dry soil conditions can reduce the availability and uptake of key nutrients. Foliar nutrition provides an effective way of delivering nutrients directly to the crop, helping maintain nutritional balance during periods of stress.

OMEX Foliar Solutions for Heat Stress

BIO 20

Best suited for: General heat stress support

BIO 20 combines mineral nutrition with seaweed-derived biostimulant properties to support crops under periods of environmental stress.

Benefits

Supports crops exposed to high temperature stress
Combines nutrition with biostimulant activity
Encourages root development and plant vigour
Helps maintain overall crop performance during challenging conditions

Zynergy

Best suited for: Supporting tolerance to abiotic stress

Zynergy combines copper and zinc to support plant health and improve tolerance to abiotic stress. These nutrients also play important roles in plant structure, root development and physiological processes.

Benefits

Supports crops during periods of abiotic stress
Helps maintain plant nutrient health
Supports root and shoot development
Provides copper and zinc in a readily available form

K41 / K50

Best suited for: Increased potassium demand during heat and water stress

Potassium plays a central role in water management and plant function during periods of elevated temperature.

Benefits

Supports stomatal regulation and water-use efficiency
Helps maintain photosynthetic activity
Assists carbohydrate transport throughout the plant
Supports crops under heat and moisture stress

CalMax, CalMax B and CalMax Gold

Best suited for: Supporting rapidly growing tissues during hot conditions

High temperatures can limit calcium movement within the plant, increasing the risk of deficiencies in developing tissues.

Benefits

Provides readily available calcium
Supports cell wall strength and tissue development
Helps maintain fruit quality and structural integrity
CalMax B provides additional boron to support flowering, pollination and fruit set

Heat Stress at a Glance

Heat stress disrupts photosynthesis, water regulation and reproductive development.
High temperatures can reduce nutrient uptake, particularly where soil moisture is limited.
Potassium, calcium, magnesium and key micronutrients play important roles in supporting crop performance during heat stress.
Foliar nutrition can provide targeted nutritional support when root activity and nutrient uptake are restricted.
Proactive crop nutrition can help maintain yield potential, quality and crop resilience during periods of elevated temperature.