Strong Radiation and High Temperatures Stress Plants and Slow Down Growth

High radiation and heat can disrupt photosynthesis, damage enzymes, and slow down plant growth – making stress management vital for modern agriculture. This article explains how biostimulants enhance plants’ resilience by improving cellular defense, nutrient uptake, and hormonal balance. With innovations like ICL’s BecoZ® Garnet, growers can help crops maintain productivity and vigor even under extreme environmental conditions.

How Does Plant Physiology React Under Stress? 

Plants thrive on sunlight and warmth, but when temperatures soar and solar radiation intensifies, what was once life-giving quickly turns into a silent threat. Under these harsh conditions, plants undergo a series of physiological changes that, while aimed at survival, often come at the cost of growth and productivity.

Stomatal Closure

One of the first lines of defense is stomatal closure. Tiny pores on the leaf surface shut to conserve moisture, reducing water loss through transpiration. However, this protective response also limits carbon dioxide intake, a process essential for photosynthesis. With less CO₂, the plant’s ability to generate energy declines, slowing the synthesis of carbohydrates and affecting overall biomass accumulation.

Enzyme and Protein Degradation

Heat stress also damages essential proteins and enzymes, particularly Rubisco, the key player in photosynthesis. When exposed to high temperatures, these delicate molecules lose their structure and function, interrupting the energy-producing processes within the chloroplasts. At the same time, heat destabilizes membranes, reducing the plant’s ability to capture and convert light efficiently.

Oxidative Stress

As if that weren’t enough, intense sunlight often leads to oxidative stress. The flood of solar energy overwhelms the photosynthetic systems, triggering an overproduction of reactive oxygen species (ROS), highly unstable molecules that damage cells from the inside. ROS attacks lipids in membranes, fragments DNA, and degrades proteins, weakening tissue from the roots to the leaves.

What Are the Visible Impacts on Crops?

These internal disruptions show up quickly in the plant’s growth pattern. Development slows down, cell division and leaf expansion stop, leading to stunted plants that struggle to cover ground or absorb light effectively. When flowering begins, the stress worsens. Pollen loses viability, fertilization rates drop, and fruit set becomes erratic. As a result, harvests are not only smaller but often of lower quality.

The heat affects plants even below ground. Root growth slows, water absorption weakens, and nutrient uptake falters. Key minerals like potassium, which aids in stomatal function, and calcium, vital for strong cell walls, become harder for the plant to access. These deficiencies exacerbate visible symptoms of stress – wilting, poor flowering, and uneven fruiting.

Why Are Biostimulants Important in Stress Management? 

Modern agriculture is embracing biostimulants as part of a multi-layered defense against climate-induced stress. But their success hinges on being used in tandem with a well-balanced fertilization program. Biostimulants do not replace fertilizers, they complement them by enhancing the plant’s internal resilience and optimizing physiological responses.

Enhancing Cellular Defense

One key benefit is biostimulants‘ ability to strengthen stress tolerance at a cellular level. Biostimulants containing amino acids, seaweed extracts, humic acids or other ingredients activate the plant’s antioxidant systems, helping neutralize reactive oxygen species (ROS) before they damage tissues. This protects photosynthetic machinery, supports enzymatic activity, and reduces the risk of oxidative injury in leaves and roots.

Supporting Water and Nutrient Uptake

Moreover, biostimulants can improve water and nutrient uptake by stimulating root growth and increasing the permeability of root membranes. In hot conditions where stomatal closure limits internal transport, biostimulants help maintain essential functions by enhancing nutrient mobilization—especially for potassium, calcium, and micronutrients needed for reproductive success and cell wall stability.

Boosting Hormonal Balance

In flowering and fruiting stages, certain biostimulants support hormonal balance, boosting levels of cytokinins and gibberellins that are often suppressed during heat stress. This leads to better pollen viability, improved fruit set, and more uniform seed development – even under suboptimal conditions.

Smart Strategies for a Tough Climate

Especially for situations with extreme heat, ICL has formulated BEOZ® Garnet, a biostimulant with a targeted blend of amino acids supplemented with a trace element package and powered by ICL’s proprietary Metabolite Technology. The amino acids and peptides contained in this product overexpress genes responsible for Induced Systemic Resistance (ISR). This response help plants fight better the effects of oxidative stress caused by excessive solar radiation and high temperatures.  The results include improved vegetative growth and root development leading to better yields even in abiotic stress conditions.

Combating the effects of strong radiation and high temperatures is not about choosing between fertilization and biostimulants – it is about integrating both. Fertilizers provide the nutritional foundation plants need, while biostimulants unlock the plant’s own capacity to endure stress and sustain growth. Together, they form a powerful strategy to protect productivity, improve quality, and future-proof agriculture against increasingly unpredictable weather patterns.