Drought is one of the major challenges facing modern agricultural production. When high temperatures persist and rainfall is insufficient, the consequences are not limited to the soil surface – they can also directly affect yield. Plants alter the way they take up nutrients, reduce photosynthetic activity, regulate stomatal opening and closing, experience changes in water status, and face increased oxidative stress.

Therefore, the question is not only how to provide plants with water, but also how to help them use the available water and nutrients as efficiently as possible.

This is why plant biostimulants are receiving increasing attention, particularly under conditions of heat and water stress. Biostimulants are not a substitute for water or irrigation, but they can be part of a broader strategy to support plants under drought conditions and help maintain their physiological potential.

How Does Drought Affect Yield?

When there is insufficient water in the soil, plants enter a state of water stress. One of their first responses is to reduce water loss through stomatal regulation and closure. However, this also reduces gas exchange, which can limit photosynthesis.

At the same time, water deficiency can make the uptake and transport of certain nutrients more difficult. Root activity may decline, while the production of reactive oxygen species increases, potentially leading to oxidative damage.

As a result, severe and prolonged drought can affect the plant’s entire production potential:

• reduced root development,
• lower photosynthetic activity,
• impaired nutrient uptake,
• disturbed plant water status,
• reduced growth and development,
• increased oxidative stress,
• reduced yield and yield quality.

In other words, during drought, a plant does not simply lose water. It attempts to redistribute its resources and adapt to unfavorable conditions.

Can Biostimulants Help Plants Under Drought Stress?

Biostimulants are not a substitute for water and cannot eliminate the effects of extreme drought. Their role is different: they can support physiological processes that enable plants to use available resources more efficiently and maintain their functionality for as long as possible during periods of stress.

The effect of a biostimulant depends on its composition, plant species, growth stage, stress intensity, application rate, and method of application.

Therefore, biostimulants for drought stress should not be viewed as a universal solution, but rather as one component of a broader plant stress-management strategy.

Humic Acids: Supporting Root Function and Nutrient Uptake

Humic acids are one of the fractions of humic substances. Their role is not limited to the soil. Research indicates their potential influence on root development, nutrient uptake, cell membrane function, plant water status, photosynthesis, and redox balance.

This is particularly relevant during drought, when both root function and nutrient availability are under additional pressure.

In experiments with maize, humic acid application was associated with better maintenance of relative water content, photosynthetic activity, and chlorophyll content, together with reduced oxidative damage.

Therefore, humic acids under drought conditions can be considered a component supporting root function, nutrient uptake, and the maintenance of plant physiological activity.

Fulvic Acids: Supporting Nutrient Utilization and Physiological Activity

Fulvic acids are the soluble and more mobile fraction of humic substances.

Their application has been associated with more efficient utilization of certain nutrients and support for various plant physiological processes.

Results from experiments conducted under drought conditions are particularly relevant. In maize, foliar application of fulvic acid during drought stress was associated with the preservation of chlorophyll content and gas exchange, as well as increased antioxidant enzyme activity. Similar results have been reported in other plant species, including cucumber, tomato, and oilseed rape.

Therefore, fulvic acids can be considered a component that supports the efficient use of available nutrients and water, the maintenance of photosynthetic activity, and antioxidant protection.

Why Are Micronutrients Important When Plants Lack Water?

During drought, it is not enough to consider only the amount of water available to the plant. It is also important that plants have access to the elements required for essential metabolic processes.

According to its declared composition, KONTUR products contain a complex of micronutrients: iron, zinc, magnesium, copper, manganese, and molybdenum.

Each of these elements has a specific role.

Iron is involved in electron transfer, energy production, and chlorophyll biosynthesis, making it important for the normal functioning of the photosynthetic apparatus.

Zinc is involved in the activity of numerous enzymes, growth regulation, and protein metabolism. Adequate zinc nutrition can contribute to stomatal regulation, maintenance of plant water status, and antioxidant protection under drought conditions.

Magnesium is the central atom of chlorophyll and is directly involved in photosynthesis. It also participates in enzyme activation and energy metabolism.

Copper is involved in photosynthesis, respiration, electron transport, and the activity of numerous enzymes. Proper application rates are particularly important, as excessive copper levels can cause oxidative stress and plant damage.

Manganese is important for photosynthesis and antioxidant protection, including as a cofactor for enzymes involved in controlling reactive oxygen species.

Molybdenum is required in very small quantities but is involved in enzymes associated with nitrogen metabolism. Research in winter wheat indicates its potential importance for water use, antioxidant defense, and osmotic adjustment under drought conditions.

Therefore, under drought conditions, providing plants with appropriate nutritional support is important to help maintain the metabolic processes required for growth, photosynthesis, and the plant’s response to stress.

KONTUR Products and Support Under Drought Conditions

Drought is a complex form of stress and therefore cannot be addressed through a single component.

According to its declared composition, KONTUR products contain 70 g/L humic acids, 30 g/L fulvic acids, and a complex of micronutrients.

The concept behind a combined approach is simple: different components can support different plant functions.

Humic and fulvic acids are associated with root function, nutrient availability and utilization, and the maintenance of physiological activity. Micronutrients provide essential cofactors required for enzyme activity and the functioning of the photosynthetic apparatus.

The goal is not to make the plant “not feel” drought. The goal is to support its natural stress-response mechanisms and its ability to recover following stressful conditions.

When Is the Right Time to Support Plants Under Drought Stress?

When dealing with drought, it is important to think ahead.

A biostimulant treatment should not be viewed as an intervention capable of restoring a crop that has already been completely destroyed. The more severe and prolonged the stress, the lower the plant’s ability to recover.

That is why supporting plants under drought conditions should be planned as part of the overall production strategy, rather than considered only after visible symptoms of stress have already appeared.

Stress management includes:

• selecting an appropriate variety,
• conserving soil moisture,
• appropriate soil management,
• balanced plant nutrition,
• irrigation where available,
• timely application of biostimulants,
• and other appropriate agronomic practices.

Drought Does Not Have to Mean Giving Up on Yield

Drought is a complex problem. During water and heat stress, plants simultaneously attempt to conserve water, maintain photosynthesis, take up available nutrients, and protect their cells from oxidative stress.

Therefore, the response cannot be based on a single measure either.

A biostimulant is not a substitute for water, irrigation, or good agronomic practices. It is a means of supporting the plant when its natural defense and adaptation mechanisms are under additional pressure.

This is why, when managing drought stress, we should not ask only how much water the plant has, but also how efficiently it can use the water that is available.