Introduction

Stomata are small openings found on the surface of leaves that play an important role in the process of photosynthesis, respiration and transpiration. These microscopic pores regulate the flow of water vapour, carbon dioxide and oxygen in and out of the plant. However, the number of stomata present on a leaf varies depending on several factors, with one of the most critical being water availability. This article seeks to explore the relationship between the number of stomata and the amount of water present in plants.

The Role of Stomata in Plants

Stomata are crucial since they enable plants to exchange gases with the surrounding atmosphere. During photosynthesis, plants take in carbon dioxide through the stomata and release oxygen, which is then used by animals for respiration. The second role of stomata is to regulate the amount of water vapour transpired. Generally, the more stomata a leaf has, the more water that will be transpired, which is one reason why water-stressed plants reduce their stomatal density.

What is Stomatal Density?

Stomatal density refers to the number of stomata on a unit surface area of a leaf. It is measured using a microscope and expressed as stomata per mm2. Generally, the stomatal density across various plant species ranges from 100 to 2,500 stomata per mm2. Stomatal density is influenced by many factors such as environmental factors, the age of the plant, light intensity and carbon dioxide levels, among others. However, water availability is one of the critical factors that directly affect stomatal density.

Why Do Plants with More Water Have More Stomata?

The number of stomata a plant has is directly related to the amount of water present in the plant's tissues. Plants that have more water have more stomata since the size of cells and tissues increase in water-rich environments. When a plant absorbs more water, the cells become turgid, which causes a small gap to emerge between cells. These gaps allow the plant to expand, leading to an increase in stomatal density.

Research has shown that there is a positive correlation between water availability and stomatal density in plants. In a study conducted on the resurrection plant, Selaginella lepidophylla, researchers observed that the plant had low stomatal density when in a dehydrated state. However, once the plants absorbed water, there was an increase in stomatal density. This finding suggests that the availability of water is a critical factor that determines the number of stomata on a plant leaf.

What are the Benefits of More Stomata in Plants?

Plants with higher stomatal density demonstrate several advantages. One advantage is that they perform better in environments with high carbon dioxide levels. In such environments, these plants can absorb more carbon dioxide, resulting in higher rates of photosynthesis. Additionally, plants with more stomata can also emit more water vapour, which in turn cools the plant and provides a mechanism for reducing heat stress. This is especially important for plants growing in hot and dry environments.

Conclusion

Stomata play a critical role in the survival of plants. The number of stomata on a plant leaf is directly related to the amount of water present in the plant's tissues. Plants with higher stomatal density exhibit several advantages, including higher carbon dioxide absorption rates and better cooling mechanisms. It is therefore essential for plant growers to consider the water needs of their plants when aiming to optimize growth and yield.