Plant Growth Regulators


There are multiple external factors in the play that assists in the course of the growth of plants. The course of growth in plants is noticeable through all the organs. These growths are also prompted by organic compounds which are the growth hormones. There are multiple hormones present in plants that assist in the elongation of the overall plant along with their respective organs.

What are plant growth regulators?

The regulators that assist in the enlargement of various parts of the plants are called plant growth regulators. These are molecules that influence the development of plants and are mostly active at minimal concentrations. These hormones are produced at the sites of that plant in itself. These hormones are commonly called phytohormones.

Hormones of the plant are proactive in every phase of plant life; potentially cells present in every site of the plant produce these hormones. Primarily there are five distinct kinds of hormones in the plants with their distinct sets of functionalities.

Plant growth: types

  • The meristematic cells aiding in the course of lengthening of plant bodies are known as primary growth. The secondary growth enhances the diameter of the body of a plant by dividing the secondary meristem.

  • Most plants are known to have an indeterminate growth process.

  • Reproductive growth is noticed in plants with flowers.

  • In the case of growth related to vegetation, stems, branches and leaves are produced. The flowers are excluded from this format of growth.

Plant growth regulators: discovery

The initial course of a major break for the discovery of the presence and effect of plant growth hormones was noticed by Charles Darwin and his son Francis Darwin. They have observed the course of phototropism.

The course of phototropism is the process where the plant grows in response to the external stimuli of light. This process is aided by the presence of the primary component present in the auxins which are the IAA molecules. The isolation of this product was carried out by F.H. Went. Later on, numerous scientists contributed to the identification of various growth hormones that aid in the growth of specific regions in plants.

Plant growth regulators: Characteristics

The growth hormones which are present in plants are known to exhibit certain traits of characteristic features. They aid in the enlargement and subdivision of cells, and they help in the formation of leaves, stems, and flowers. These hormones help in wilting of the leaves.

Primarily, there are five kinds of hormones in plants that helps in all these processes. These hormones ripen the fruits and further help in courses of dormancy in seeds.

Plant growth regulators: types

The growth regulators that are found in the plants are of two distinct types those that inhibit the growth like abscise acid and ethylene and others are responsible for the promotion of growth in various parts of the plants. In general, these are organic compounds that extensively manipulate the physiological structure and functioning of the plants.

There are in general five different kinds of plant hormones to be found in plants. Some hormones are enlisted below


Auxins are the foremost hormones that are responsible for elongation in the cell of plants. These are also needed for the subdivision of meristem into vascular tissue further enabling the progress of the leaves and their arrangement. These hormones also assist in the differentiation of the xylem and further help in the division of cells. These are also used as herbicides to remove dicot weeds.


These hormones are involved in the course of elongation of the leaves. These are responsible for the elongation of shoots and it helps in the regulation of dormancy in plants. Gibberellins assist in the process of bolting in cabbages. They help in the elongation of fruits and help them in attaining proper shape.


These hormones are responsible for the division of cells and dominance in the apical region. These hormones are responsible for keeping the flower fresh for a longer duration of time. In the case of the buds in the lateral region, these hormones enable the growth.


Regulators present in plants assist in the growth of development and progress of various parts of plants. These are multiple stages of growth in plants that are to be found from the root to the shoot. The hormones that are present in plants assist not only in growth but various functionalities and character traits as well. The growth promoters and inhibitors present in the plants help them elongate, function, and prosper further.


Q1. What are plant growth inhibitors?

Ans: These hormones are one of the key components of the growth regulators to be found in plants. There are primarily two kinds, abscise acid, and Ethylene. It helps in the maturation and growth of seeds. This acid further helps in the course of dormancy and abscission. Ethylene on the other hand helps in breaking of dormancy of seeds and enhancing the rate of respiration during fruit ripening stages.

Q2. What are the growth regulators of plants?

Ans: The growth regulators of plants are the chemical components that are directly involved in the growth and differentiation of cells in plants. These are chemical messengers that help in the communication of intracellular regions.

Q3. What are the external factors that affect the growth of plants?

Ans: Combined with the plant hormones there are certain external factors in the play that assists in the development of the plants. These organisms are mostly light, water, and the nutrients that have been derived from the soil which is useful for photosynthesis.