PGR Growth regulators. Introduction (1/3)

Grasses, lacking a nervous system to respond to different environmental stimuli, use hormones to promote and inhibit their growth. These hormones and their functions are presented below:

Growth-promoting hormones:

Auxins:

• Production: Generated in the meristematic tissue.
• Functions: They are distributed throughout the plant and influence cell elongation, inhibit lateral growth and leaf ageing, and promote seed formation and root growth.
• Additional effects: High levels of auxins can inhibit growth depending on the plant tissue. Some herbicides, such as 2,4-D, used to control broadleaf weeds, are based on auxin content.

Gibberellic acid:

• Production: It occurs in the meristematic tissue of young leaves, roots and seeds.
• Functions: Promotes cell division, cell elongation and seed germination.
• Commercial applications: There are commercial preparations of gibberellic acid, used, for example, for greening bermudagrass.

Cytokinins:

• Production: They occur at the tips of the roots.

• Functions: They stimulate cell division and inhibit leaf ageing.

• Resilience: They help the plant to overcome certain environmental stresses.

Growth inhibiting hormones:

Ethylene:

• Production: It is a gas produced in leaf tissue.
• Functions: It promotes leaf ageing, and inhibits root and lateral growth and cell elongation.

We have the technology KeepCool designed specifically for the ethylene removal during transport and storage sod cooling of turf. This solution prolongs the life of turf, maintains its freshness and vitality, and reduces economic losses due to deterioration. It is ideal for growers, distributors and greenkeepers looking to optimise the quality and durability of their products.

Abscisic acid:

• Production: It is produced in chloroplasts.
• Functions: Promotes stomatal closure and plant ageing.
• Effects of stress: It is generated in response to high levels of drought stressexcess humidity, nutritional deficit or excess salinity.

Growth regulators

The growth regulators The production of these hormones is the basis for turfgrass establishment. Determining the ideal time for the application of these regulators is based on the growth potential curves: the greater the difference in these curves, the lower the competition between species and the greater the ease of turf establishment.

A turfgrass growth regulator is a chemical used to control and manage the growth of grasses in turf areas such as golf courses, parks and residential gardens. These regulators alter the physiological processes of plants, such as cell division and stem elongation, slowing the vertical growth of turf. By slowing the rate of growth, they reduce the frequency of mowing, which saves time and reduces maintenance costs. In addition, these regulators help maintain a dense, healthy turf by promoting more horizontal growth, which promotes uniform coverage and minimises the appearance of bare or damaged areas.

Advantages:

• Increased drought resistance: Studies on C3 varieties have shown that the application of growth regulators increases drought resistance, as the slowing of growth and the physiological processes promoted reduce the plant's water demand. Similar studies at the University of Arkansas have shown comparable effects on hybrid Bermuda fairways (Source: Brouwer, N. 2014. University of Arkansas).
• Suspension of gibberellic acid production: This hormone is responsible for vertical growth. Although all other physiological functions are maintained, growth is slowed down, reducing the need for frequent cutting and thus reducing stress for the plant.
• More efficient growth: Although growth is not directly more horizontal, by spending less energy and resources on post-mowing repair, the turf becomes more efficient in its horizontal growth. However, the final growth depends on the balance and NPK values.
• Application after scalp: It is especially beneficial to apply the growth regulator after a scalp, as the growth response is predominantly vertical.
• Reduction of NPK requirements: Less NPK is required to maintain the same grass colour.
• Reduction of water consumption.
• Lower incidence of disease: Fewer open wounds reduce the incidence of disease.
• Use in reseeding: In particular, its use in reseeding of Rye-Grass on Bermuda is frequent.

Disadvantages:

• Risk of overdose: May cause discolouration that takes time to recover.
• Errors in implementation: They can cause areas of uneven growth, creating an aesthetic effect that takes time to correct until the regulator stops working.
• Marks due to use of the turf: Marks caused by the use of turf take longer to disappear.
• Effects of intense herbicides: If a herbicide is applied too heavily, yellow-marked grass will take longer to recover.
• Rebound effect: Growth regulators suppress growth, but once they have worn off, they can cause excessive growth. It is necessary to overlap treatments to avoid these rebounds.

General considerations:

Hormone-based: Growth regulators act through the production of specific hormones.

Ideal time of application: The best time to apply these regulators is determined by the growth potential curves. A greater difference in these curves reduces competition between species and facilitates turf establishment.