Phases of plant growth and plant growth rate

Introduction

Growth is defined as a vital process that brings about an endless and unrecoverable change in any plant or its part in respect to its size, form, weight, and volume. Growth is confined only to living cells and is fulfilled by metabolic processes. The plant growth rate depends on numerous factors. Cells don’t increase in size but divide, giving rise to daughter cells. An important process during cell division is the synthesis and replication of nuclear DNA in the chromosomes, which is also passed into the daughter cells. Thus, the term growth is used to denote an increase in size by cell division and cell blowup, together with the conflation of new cellulose accoutrements and the association of cellular organelle.

The daily requirements of a plant are light, water, air, nutrients, and a proper temperature, which results in a healthy plant. The relative significance of each of these requirements differs extensively among plants. The capability of a plant species to spread throughout a geographic area directly results from its adaptation to the abiotic and biotic factors of the area. The conception of limiting factors applies to all aspects of a plant’s interaction with its habitat.

Factors that affect plant growth rate

Generally, plant growth is affected by several factors: external and internal. External factors are present in the environment and affect the growth of the plants directly or indirectly. These factors are:

  • Light 

It is a basic necessity for plants to perform photosynthesis. Apart from that, it is necessary for seed germination, growth of the seedling, and reproduction

  • Temperature

It depends upon plants and where they grow. The optimum temperature for growth ranges between 28 and 30 degrees. All the activities performed by plants are affected by temperature.

  • Water

It is important to have an adequate amount of water in plants as some are lost during transpiration. Excess and deficiency of water can harm plant growth.

  • Mineral nutrients

All metabolic processes require nutrients. Plant growth is affected by deficiency of nutrients. 

Phases of plant growth

Growth may be defined as an unrecoverable increase in the number and size of a cell, organ, or whole organism. Growth occurs in three stages: meristematic, extension, and development. 

  • Meristematic Phase 

The meristematic phase, also known as the constructive phase, is characterised by the constant splitting of root and shooting apex cells. The meristematic region’s cells are protoplasm-rich and have a big nexus. 

  • Extension Phase 

The extension phase is represented by cells close to the meristematic zone. This phase is marked by enhanced vacuolation, cell blow-up, and the formation of new cell walls.

  • Maturation Phase 

After extension, the maturation zone comes next. In aspects of wall thickening and protoplasmic changes, the cells in this region reach their maximum size. These cells produce basic and complicated tissues that serve a variety of purposes.

What are the four stages of plant development?

  • Seed of the plant 

Plants that reproduce sexually begin their cycle with a seed, where it can germinate and grow if the conditions are favourable. These seeds consist of the embryo. 

  • Germination

Once the seed is in a place where conditions are optimum for its birth, the germination phase begins. Many days later, the first evolution of the seed will crop, which will grow and grow, taking on an aspect analogous to a common root. 

  • Seedling

Once the plant begins to grow, its youthful state is called “seedling,” where the cotyledons (early leaves) will be open, and the plumule will develop, which will allow the growth of its first leaves. 

  • Mature plant 

At this stage of the life cycle of the plants, they start to generate their food to continue growing, a process that’s called photosynthesis, and the capability to do so is when the first leaves are visible.  

 Chemical substances that regulate plant growth

  • Auxin 

Auxin is a chemical that promotes growth and is produced in the growing apex of the stem. It helps in the elongation of the shoot and root tips. 

  • Gibberellins 

Gibberellins is a chemical that is produced in embryos, roots, and young leaves to promote growth. It also helps in the elongation of stems and breaks the dormancy of seeds and buds.

  • Cytokinins 

Cytokinins are made in the root apex, the endosperm of seeds, and in fruits, where cell division occurs regularly. It is responsible for stimulating cell division, enlargement, and cell differentiation. They also prevent the ageing of some parts of the plant.  

  • Ethylene

It is a chemical found in ripened fruits, young flowers, and young leaves. It is responsible for the increment of cell width and not the length. It ensures that the fruits are ripped and promotes senescence of leaves and flowers.  

  • Abscisic acid

Abscisic acid, formerly known as Dormin, is a naturally occurring growth chemical found in various plants. It is made of leaves. Its function is to inhibit seed germination and development. It also promotes senescence of leaves. 

Conclusion

In a nutshell, plants are vital to all life on Earth. Plants play an important role in consuming carbon dioxide and producing oxygen. In addition, plants make up the base of the food web by producing their food using light, water, carbon dioxide, and other chemicals. We are all interlinked and interdependent. Various factors affect the plant growth rate, and with the increasing weedy crops, plant gene modification has been introduced. Each country has a different geographic area, and the requirements for the plants vary. So each country will have to determine its own modified plant to have a positive impact on the environment.

 

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