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Plant Growth Regulators A Major Component in Modern Agriculture
2021/11/19 11:16:32

Plant Growth Regulators

A Major Component in Modern Agriculture


Plants require light, water, oxygen, minerals and other nutrients for growth and development. In addition to these external requirements, plants rely on certain organic compounds to signal, regulate and control plant growth. These substances we will call Plant Growth Regulators (PGR).

What is a plant growth regulator?

Plant growth regulators are molecules that affect plant development and are usually active at very low concentrations.

PGR play an important role in the growth and flowering of the plant, among other things:

  • Differentiation and elongation of cells.

  • Formation of leaves, flowers, and stems.

  • Wilting of leaves.

  • Ripening of fruit.

  • Seed dormancy.

The most well-known PGRs are Auxins, Gibberellins (GAs), Cytokinins, Ethylene and Abscisic acid (ABA). In addition to these, there are more derivative compounds, both natural and synthetic, which also act as plant growth regulators.

Based on different PGR actions, they are broadly classified into two types:

  • Plant growth promoters: Auxins, Gibberellins, and Cytokinins

  • Plant growth inhibitors: Abscisic acid and Ethylene


An overview of which plant hormone is responsible for which plant process.


The main effect of auxins is to cause cell elongation, mainly due to the alteration of cell wall plasticity. Auxins are synthesised in the apical meristems and to a lesser degree in the roots. The main auxin to be synthesised naturally by plants is Indole acetic acid (IAA), although others have been found such as phenylacetic acid, the chlorindoles and, more recently, Indole butyric acid (IBA). The movement of these phytohormones is from the apices to the roots (basipetal) and vice versa (acropetal). However, basipetal movement is much more rapid than acropetal movement.


Benefits for plants:

  • Influence cell growth expansion and elongation

  • Stimulate root formation

  • Induce vascular differentiation

  • Promote tropic responses

  • Maintain the apical dominance (the main, central stem of the plant is dominant over other side stems)

  • Delay leaf senescence (which is when leaves are close to dying in the plant life cycle)

  • Induce the development of auxiliary buds, flowers, and fruits



Gibberellins work as growth accelerators, causing cell stretching and cell division. They ensure that seeds germinate and that flowers form in plants that need long days.


Benefits for plants:

Stimulate & Regulate the Plant Growth

  • Induction of growth and elongation of plant structures

    The physiological mechanism that allows elongation is related to changes in endogenous calcium concentration at the cellular level.

  • Stimulation of germination

    Gibberellic Acid activates the mobilization of the reserves, inducing the synthesis of amylases and proteases in the seeds.

  • Promotion of fruit set from flowers

    Gibberellic Acid favors the development of fruits, stimulating the setting or transformation of flowers into fruits

Increase the Crops Yield


      Fruit Thinning

      Reduce Vegetative Growth

      Increase Fruit Size

      Hasten Maturity

      Bunch Elongation (Stretch)


     Improve Fruit Quality

      Reduction in Severity of Creasing


      Produce Larger

      Brighter Colored

      Firmer Fruit


      Facilitates Harvest

      Increases Yield

      Improves Quality


      Promotes Panicle Exertion

      Improves Pollination and Yield

      Increases Tillering of The Ratoon Crop

Pasture Grass           •      Stimulate Production

Improves the Plant Immunity

Gibberellic Acid helps to withstand stress conditions like drought, frost and attack of insects.

The Effect of KING'S Gibberellic Acid


Harvest timeJune 22May 26 27 days earlier
The hay quality275 kg 323 kgincrease of 48 kg

Average height at harvest

65.3 centimeters73.2 centimetersup 7.9 centimeters

Average results of 290 trials in 2 years: Feed corn yield increased 9 bushels/acre (38.1 kg/mu)


Cytokinin is a natural substance can helping plant cells to multiply. The main function of the cytokinin is to produce cell division and retard senescence. They also stimulate the development of lateral apices when applied exogenously, breaking apical dominance.

Benefits for plants:

  • Affect mitosis (chromosomes are separated into two new nuclei) and cytokinesis (cytoplasm of a parental cell is split into two daughter cells)

  • Promote lateral bud growth and leaf expansion

  • Delay leaf senescence

  • Promote chlorophyll synthesis

  • Enhance chloroplast development


In 1934, it was discovered that plants produce ethylene themselves, which enables them to regulate fruit ripening. Ethylene is a gaseous hormone which is transported via the spaces between plant cells.


Benefits for plants:

  • Promotes the development of root and shoots

  • In conjunction with other phytohormones, this gas promotes fruit ripening, senescence, and leaf abscission.


Administering ethylene results in smaller plants and flowering finishes a lot quicker. The flowers ripen too quickly and consequently remain small. Concentrations of just 10 ppb can cause abnormalities in tomatoes. In situations where ripening flowers come into contact with young plants there is a risk of accelerated ripening in the young plants. The ethylene that is produced can reach the young plants via the air. Ventilating occasionally (once daily) will remove any ethylene that has accumulated. Higher concentrations of ethylene cause leaves to turn yellow immediately.


Abscisic acid

Abscisic acid is directly implicated in the senescence and abscission of leaves, flowers and fruits. It also affects the latency of some seeds.

Abscisic acid is found as both the active isomer S-ABA and the much less active isomer R-ABA.


KING'S S-Abscisic Acid contains the highly active S-ABA form of Abscisic acid.

Benefits for plants:

  • Regulate seed germination

  • Induce storage protein synthesis

  • Modulating water stress

  • Maintains bud and seed dormancy (seed remains asleep or inactivated)

  • Slows cell elongation

  • Regulate the closing of stomatal apertures (reducing transpiration)

  • Play a role in seed maturation

  • Modulate leaf abscission and senescence

KING'S S-Abscisic Acid                  Ethephon               

Compared with Ethephon, KING'S S-Abscisic Acid can protect the brush and makes the grapes less likely to drop.

The Effect of KING'S S-Abscisic Acid

On Table Grapes


Enhance Color Development of “Jingya“Grapes


Enhance Color Development of KyohoGrapes

On Cotton


KING'S S-Abscisic Acid Promote the Quality of Cotton Boll

Now we see how important the plant growth regulators in the growth and development of plants are. Before you use them, please Read the product label and follow all safety precautions.For additional information on plant growth regulators, you can contact King Quenson at any time.


Tel: 86-755-86612769


Since 2003, King Quenson has been thriving to introduce the latest technologies to agricultural industries and farmers to achieve mutual development and prosperity. With years of dedication and rich experience, King Quenson devotes more than 18 years to crop protection and offers solutions.

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