Acclimatization: Unlocking the Secrets to Successful Plant Growth

Have you ever wondered why a significant percentage of crops fail during the acclimatization stage? The key to achieving success in tissue cultured plants lies in their seamless transition from a controlled lab environment to the natural world, while ensuring a high survival rate and cost efficiency. In the lab, these plants are nurtured like delicate babies, thriving in a completely controlled environment with carefully regulated conditions. Every nutrient and mineral needed for their healthy growth is provided, and factors such as light, humidity, and temperature are meticulously adjusted according to each plant’s requirements.

But what happens when these laboratory babies are ready to face the challenges of the outside world? Directly transferring them from the lab to natural conditions would be a fatal mistake, subjecting them to undue stress. The transfer of plantlets to the natural environment is a gradual and methodical process that guarantees their productivity and survival. In this article, we will explore the concept of acclimatization and delve into the proper methods for achieving successful results. So, let’s begin!

What is Acclimatization?

Acclimatization is the process by which organisms adapt to a new environment. When tissue cultured plants are moved from the lab to the soil, they are exposed to abiotic stresses, such as changes in temperature, light intensity, humidity, and biotic stresses, like the presence of soil microflora. Therefore, they require a step-wise acclimatization process to establish themselves successfully in their new natural environment.

Acclimatizing Tissue Culture Plants

The Challenges of Acclimatizing Plants

In the lab, plants are raised in an artificial environment, depending on external sources for their nutrients. As they develop, they transition from being heterotrophic to mixotrophic. However, for plants to thrive in the natural world, they must become autotrophic, capable of producing their own food. Tissue cultured plants have different anatomy and nutrient requirements that hinder their ability to become self-sufficient. Consequently, a gradual transition is necessary to help them adapt to these changes.

The controlled environment in tissue culture includes constant temperature, high humidity, ample nutrients, low light intensity, and a low concentration of carbon dioxide (CO2). These conditions make it challenging for plants to adapt to the outside environment. Here are some features that differentiate in-vitro plants from ex-vitro plants and contribute to the difficulty of acclimatization:

  1. In the multiplication and rooting stage, the high humidity suppresses the production of epicuticular wax and disrupts the normal functioning of stomata, leading to the unhealthy development of secondary roots.

  2. The high humidity, combined with the stagnant air and nutrient-rich medium, inhibits water and nutrient uptake by the plantlets during the multiplication and rooting stages. This results in growth retardation, physiological disorders, and variations in size and developmental stage.

  3. The low light intensity, low CO2 concentration, and high sugar content in the media result in a low net photosynthetic rate, minimal leaf formation, and slow growth rate.

These factors contribute to the low growth and survival rate of tissue cultured plants during the acclimatization stage.

How to Successfully Acclimatize Plants?

The physiological and anatomical deficiencies in tissue cultured plants can negatively impact their survival. So, how can we ensure a successful acclimatization process? What factors should be considered?

First and foremost, it is necessary to transfer the plants from the lab environment to a greenhouse that replicates the same conditions. To facilitate this transfer, gently wash the plantlets under running tap water to remove any residual media, and then place them in a potting mix that is irrigated with an inorganic nutrient solution. Various potting mixes are available, such as pumice, peat, vermiculite, soil, and sand.

In the provided video, the potting mix consists of a combination of Sphagmoss (Sphagnum Moss), vermiculite, perlite, and water. This mix is evenly distributed in the cups of a tray, and the plantlets are divided into small clusters and placed in the tray.

The First Two Weeks

For the initial 10-15 days, it is crucial to maintain high humidity, similar to the conditions in which the plants were cultured. This can be achieved by covering the plants with transparent plastic bags, which should have small holes for proper air exchange, and placing them in shaded areas. This shading protects the plants from direct exposure to sunlight, which can result in excessive water loss. The video demonstrates the use of a tray with a regulator to control the environment.

The transition from an organic nutrient medium to an inorganic one might initially shock the plantlets. However, this change activates their photosynthetic machinery and prepares them to withstand lower humidity levels. Nowadays, computer-controlled rooms are available that maintain high humidity, sufficient light, and appropriate CO2 levels, ensuring optimal conditions for photosynthesis.

Another approach to enhance the survival and growth rate of plants during the acclimatization stage is to provide a greenhouse environment for the plantlets, similar to the conditions during the multiplication and rooting stages.


Acclimatization is a crucial step in the successful growth of tissue cultured plants. Understanding the challenges they face in transitioning from a controlled lab environment to the natural world is vital. By implementing proper acclimatization techniques, we can ensure the survival and productivity of these plants. Remember, patience and a step-by-step approach are key. With careful attention to detail, we can guide these delicate plants towards a thriving future in the outside environment.


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