Factors that affect plant growth: internal and external

The main factors that affect plant growth are water, light, temperature, humidity and nutrients. However, there are a number of other factors both internal and external that definitely also intervene in a relevant way in its entire development process.

These factors have been classified as internal and external, to make a much simpler delimitation of how they really intervene in the process. These are divided in turn into biotic, abiotic, hormonal and genetic.

Each one makes a different contribution to the composition of the plants and their development, which we will know in depth in the following paragraphs. In the meantime, we must add that it is important for plants to have access to most of these factors in order to grow healthy and achieve each of their physiological and morphological processes.

Since there are environmental stresses, although plants have the ability to adapt to certain environments and respond to certain stimuli, they often suffer from environmental stress; which atrophies their health, slows their growth or can cause their death.

What that tells us is that, since a seed is sown, its cells begin to act in favor of the stimuli it receives from the environment in which they are and manage to grow quickly or slowly depending on them. Therefore, knowing these factors that affect their growth directly or indirectly, will solve as many problems as may arise in crop production.

The main factors that affect plant growth are external

The factors that affect plant growth, we usually know them as those factors that are in the environment (external) and that they absorb to grow, develop and produce flowering.

Among them, the most common and well-known are light (from the sun if it is in a natural environment), temperature, humidity, water and nutrients. However, there are other factors - beyond these - that also affect their growth, depending on the percentage they can receive from them.

Knowing this, we can make this classification of factors that affect plant growth and that are external, a little more specific; because in addition to those mentioned, plants also develop thanks to the intervention of abiotic and biotic factors.

In this case, the abiotic factors are directly those found in the environment and involved in the growth of plants; while biotics refer to those that, also found in the environment, are factors that relate or interact with plants to contribute to them (or damage them) in certain processes.

Each of them, in turn, is classified as follows:

Abiotic factors

In short, abiotic factors are those non-living components found in the environment that in one way or another affect the growth and development of all plants. Therefore, beyond those commonly known (light, water, temperature, nutrients and humidity), we find the following:

This factor refers in a particular way to the characteristics or arrangement of the land. Specifically, it can affect the growth of plants, because a certain altitude will cause a certain temperature and allow the circulation of a certain amount of water. Also, if the terrain is mountainous, flat or undulating, it can allow the growth of certain types of plants and not others, due to the natural conditions that characterize it.

Soils represent the surface on which most plants grow and from which - through their roots - they obtain much of their nutrients. Therefore, depending on the physical, biological and chemical characteristics that a given soil has, the development of certain plants will become possible.

On the other hand, there are thousands of living organisms found in soils; such as fungi, bacteria, protozoa, algae, among others; that in a certain way (through their survival characteristics) work the soil making it possible for nutrients to exist or for water to permeate.

On the other hand, abiotic factors, which we normally know as "environmental", affect plant growth as follows:

• Light:it is one of the factors that affect the growth of plants that has greater weight and importance, because it intervenes in their process of growth, reproduction and differentiation of their organs.
• Water:along with light, water intervenes in the process of photosynthesis of plants. It enters the organism of these through the soil and finally leaves through perspiration. It is as important as light, because it intervenes in a large part of the processes of growth and development of plants; and as well as the rest of the factors, it adheres to them in the right amount, because if it is added in excess or in less quantity, it can profoundly affect the health of the plants.
• Temperature:since a seed is planted, temperature is part of the main factors that collaborate with the development and growth of plants. Specifically, it intervenes in the metabolism of these and the cellular processes that occur in their growth process. Therefore, the variation of temperature affects their growth from the time they are seeds, until they reproduce; each type of plant requires a certain temperature at a certain stage of its growth.
• Nutrients: plants achieve optimal growth thanks to a compendium of factors that affect their growth; among them, the nutrients and minerals they absorb from the soil, air and water, are precisely responsible for various internal processes that they go through in order to develop, for example, the transport of electrons, enzymatic activity, the permeability of the cell membrane,  among others. If plants do not receive nutrients, their growth is simply delayed.

As we can understand, each of these factors that affect plant growth intervenes in their stages of development in a relevant way. Well, in the absence of any of them, the results in terms of health and durability of the plants, changes or is delayed. Therefore, by taking each of them into account - and knowing the precise way in which they affect them - we can also know how to provide them in artificial environments such as greenhouses.

Biotic factors

The factors that affect plant growth and that we consider as "biotic factors" refer to those organisms or elements that interact with plants and relate to them to produce advantages or disadvantages. These are:

Mutualism represents the factor in which the interaction between one species and another is evidenced to cause certain benefits. For example, insects and birds are pollinating agents that, by feeding on the nectar of flowering plants, transfer pollen to it and help future fruit growth.

Parasitism also consists of the interaction between two agents; but, in this case, it turns out to be a negative relationship. Parasites are organisms that benefit from the damage they cause to others so it is - as a result of them - that some crops experience losses due to diseased plants.

It refers to those animals that being herbivores (those that feed on some parts of the plants) cause damage to the plants in different measures. For example, making flowering impossible, reducing its stem, eating its leaves or causing the total death of the plant.

Genetic factors on plant growth

Like humans, plants are also made up of genes that delimit their own characteristics. That is why there are plants of different types, sizes and textures that, since they are seeds, look different.

For this reason, we say that the factors that affect plant growth (which are internal) are specifically genetic; and it is precisely they who contain the information regarding the shape that the plant will have, its growth pattern (what conditions it needs to develop) and its differentiation with other plants.

In this way, genes - which we find inside plant cells - provide them with a diversity of cells that make it possible (for example) to perform the synthesis of proteins (and other specific enzymes) or to perform and catalyze various biochemical processes that allow the process of development of these.

Hormonal factors involved in plant growth

We have mentioned that all the factors that affect plant growth are responsible for various tasks that allow the development of these to be possible. In the case of hormonal factors, these are exclusively responsible for distributing and regulating the growth of plants through the selection of elements they need and the amount of them.

In other words, they regulate the amount of water, nutrients, temperature, humidity and light that plants receive, distributing amounts of them through their organs to allow internal processes of plants, such as: cell enlargement, tropical growth, cell division and other external elements such as seed formation,  flowering and fruiting.

Likewise, the fact that they regulate the growth of plants, also intervenes in growth inhibitory processes, through which hormones are responsible for controlling the size of plants, their leaves and their fruits.

They are even responsible in part for the health of plants, since they are the ones who determine their response to the wounds or tensions that they can receive from agents or organisms that are in the environment.

Importance of knowing the factors that affect plant growth

In this way, we can say that knowing completely what are the factors that affect plant growth (beyond the common ones), will provide us with relevant knowledge regarding their growth and the way they do it, which will then allow us to create suitable environments for them, in which each of these factors can be controlled manually.

Finally, it is through the construction of greenhouses that we can take better advantage of the growth of plants, because, having a control of temperature, humidity, light and the amount of water, there will be no climate change or external organisms that can damage our plants.

Therefore, it will also be possible to have knowledge regarding the necessary equipment that will make possible the construction of this environment, by obtaining sowing in less time and that will result in healthier plants.