Articles

Phytohormones: significance for plants

13 February 2024

The agricultural sector has successfully transitioned to a “modern level”: the emergence of intensive varieties and the constant need to increase productivity per hectare have led to the modernization of farming processes and the adoption of advanced technologies.

Constantly increasing the rate of primary fertilizer application has become economically disadvantageous. It is necessary to seek other ways to improve nutrient uptake and plant stimulation. One such approach has been a shift in understanding and necessity of using foliar fertilizers. Initially, micro-fertilizers began to be used: both simple N-P-K complexes in various formulations and their combinations with mono-element micro-fertilizers (Boron, Zinc, etc.).

The development of the agricultural sector is not only accelerating but also setting a new standard. Thus, various biostimulants with high concentrations of phytohormones have actively begun to be included in technological charts. There is logic in this, as phytohormones control and coordinate all physiological functions in plants throughout the entire vegetation period: from seed to the completion of the life cycle.

Timely and targeted use of necessary stimulating substances has the potential to significantly impact crop formation. It remains only to remember which phytohormones are responsible for what and skillfully implement this knowledge in practice.

So let’s start with the simplest – auxins and cytokinins. These are the two categories of phytohormones that are most common in biostimulants. But not everyone remembers which is responsible for what and how to use them correctly to achieve maximum effect.

AUXINS – POWERFUL ROOT SYSTEM

Auxins are phytohormones produced in the young parts of plants. They play a significant physiological role in the life of the plant. The main biological functions include:

  • Establishment and development of the root system;
  • Construction of a branched root system;
  • Stimulation of cell division and enlargement;
  • Differentiation of shoot meristem tissues;
  • Regulation of processes such as flowering, fruiting, and entry into the plant’s hibernation period.

Under high intensity of light radiation, as well as under high concentrations of nitrates and manganese in the soil, the action of auxins is inhibited.

In plants, the lack of auxins disrupts the optimal balance of hormones, leading to the formation of growth inhibitors in plant tissues: ethylene and abscisic acid. The plant immediately begins to cope with stress by initiating complex physiological processes, resulting in slowed growth, necrosis, delayed flowering, and other processes.

CYTOKININS – THE HORMONES OF “YOUTH”

Cytokinins are a very important category of phytohormones. The main sites of synthesis are the tips of the roots, seeds during germination, and before maturation. The main functions include:

  • Stimulation of cell division;
  • Formation of organs for assimilate accumulation;
  • Protein synthesis;
  • Delaying aging;
  • Regulation of stomatal function, interruption of plant dormancy;
  • Activation of water and potassium uptake.

Cytokinins are involved in many physiological processes in plants: shoot and root morphogenesis, chloroplast maturation, linear cell growth, formation of additional buds, and regulation of aging processes.

Cytokinins are inhibited by hot weather and excess carbon dioxide, disruption of water balance, and nutrient deficiency.

The combination of these two phytohormones in the correct ratio can help address the following tasks:

  • Emphasis on auxins – building a strong root system, which is needed at the start of plant growth. For example, in the biostimulant Powerfol Undaria, the necessary ratio of auxins to cytokinins (350:1) is preserved, allowing for the most effective stimulation of the root system at the beginning and maintaining balanced development of vegetative mass.
  • Emphasis on cytokinins – active vegetative growth, prolongation of the vegetative period, and development of lateral shoots.

GIBBERELLINS – REMARKABLY POWERFUL GROWTH STIMULATORS

Gibberellins are an intriguing category of phytohormones. They can be synthesized in various parts of the plant organism. However, the main site of gibberellin synthesis is the leaves, predominantly young ones. Unlike auxins, gibberellins move from the leaves to other organs both via the xylem and phloem. Their primary functions include:

  • Inducing stem growth and increasing leaf size.
  • NOT affecting root growth.
  • Promoting the breaking of dormancy and seed germination.
  • Inducing parthenocarpy.
  • Controlling fruit growth and development.
  • Regulating flowering in long-day plants.
  • Promoting the formation of male flowers in monoecious plants.
  • Enhancing the pollination of plants with female flowers.

In essence, gibberellins are hormones capable of significantly stimulating stem and leaf growth by elongating cells.

BRASSINOSTEROIDS – INEFFICIENT IMMUNOMODULATOR

Brassinosteroids have been identified as the sixth plant hormone after the classical plant hormones: auxin, gibberellins, cytokinin, abscisic acid, and ethylene. Structurally, they are analogous to animal steroid hormones. Brassinosteroids play a crucial role in various aspects of plant biology:

  • Cell division and elongation.
  • Stimulating root growth.
  • Improving photomorphogenesis.
  • Stimulating the differentiation of stomata and vessels.
  • Promoting seed germination.
  • Enhancing plant immunity and resistance to abiotic factors.

Especially crucial is the latter function of brassinosteroids: they play a role in shaping the plant’s response to stressors such as temperature decrease, drought, salinity, diseases, heat, and nutrient deficiency. Highly relevant in today’s conditions!

Even at very low concentrations (10–10 M and below), this subgroup of hormones regulates a wide range of processes in plant development and responses to environmental stresses.

TRIAKONTANOL – INVALUABLE ASSISTANT

Triakontanol, being an endogenous plant growth regulator, contributes to numerous metabolic processes in plants, promoting their better growth and development.

  • It plays an important role in forming stress resistance and mitigating the effects of stress in crop plants by activating mechanisms of resilience.
  • It activates the activity of the root system and promotes the development of vegetative mass.
  • It enhances the assimilation of carbon dioxide and improves photosynthesis.
  • It increases the content of chlorophyll.
  • It boosts enzymatic activity and facilitates the absorption of minerals, thereby increasing the efficiency of using essential nutrients.
  • It promotes seed germination and rooting, increases the content of dry protein, which contributes to plant ripening.

It seems that a product containing all these advantages would be indispensable! And indeed, it is: Powerfol FitoFarm. In addition to the classic combination of auxin-cytokinin, it is enriched with a complex of gibberellins, brassinosteroids, triacontanol, and B-group vitamins. This combination makes it exceptionally effective.

Here are the results of our biostimulants’ work in field conditions:

Therefore, as you may have understood, phytohormones are a powerful force on the path to increasing productivity and maximizing profits. The key is the skilled and timely use of these hormones. Thanks to the best products, this process becomes much more effective!