Introduction

So far, more than 105 elements have been found. Only roughly 20 have been discovered to be necessary for plant development and metabolism. A lack of any element in plants can cause symptoms such as chlorosis, necrosis, stunted development, and so on. To avoid these malformations in plants, effective mineral element absorption by plants is critical.

Previously, it was widely assumed that plants take nutrients from the soil in addition to water. Further research into plant activities established that water absorption and mineral element absorption are distinct processes. The mechanism of element absorption in plants operates in two ways. Passive and active absorption are examples of this.

Mineral and Essential Element Absorption

An essential element is one that a plant cannot complete its life cycle without, and it plays a crucial physiological function in plant life. These elements have a direct role in plant metabolism and cannot be substituted by another element.

Mineral absorption refers to the process of absorbing nutrients from the soil. It occurs as a result of the root system’s close interaction with the soil solution. Root hairs are extensions of the root epidermis that remain in direct touch with soil water and minerals and absorb the water at first. As a result, they are also known as absorbent hair.

Plants’ Essential Elements Sources

Carbon, hydrogen, and oxygen are the building blocks of macromolecules, which constitute the majority of the plant body. These are not mineral elements since they are not absorbed from the soil. Similarly, nitrogen is required by plants but is not classified as a mineral element since plants need air nitrogen fixed by soil bacteria in the form of ammonium and nitrate ions.

The soil, as a whole, is the primary source of many nutrients such as phosphorus, sulphur, magnesium, calcium, potassium, and so on. These mineral elements are absorbed by plants in their ionic forms. Mineral elements are considered to be generated from parent rock weathering and retained by the soil.

Minerals Absorption Mechanism

Minerals are either dissolved or absorbed from the environment. Minerals are absorbed by epiblema cells in the root maturation and elongation zone. Mineral absorption can be divided into two stages:

1. Passive Absorption

Passive absorption refers to mineral absorption that occurs via physical mechanisms such as diffusion without the need for metabolic activity. An ion goes passively from a greater concentration or higher electrochemical potential zone to a lower electrochemical potential region. Ion channels are often used for passive ion transport. Ion channels are proteins with transmembrane membranes that act as selective apertures. Several concepts have been offered to explain how ions travel against an ECP gradient.

2. Active Absorption

Active absorption refers to the movement of ions against a concentration or ECP gradient. This movement necessitates the use of energy. Hogland investigated the active absorption and accumulation of ions against a concentration gradient in the green algae Nitella and Valonia by utilising energy. The cells of these algae continue to absorb K+ and phosphate ions to the point where their concentration exceeds the concentration of ions in the pond water by hundreds or thousands of times.

Factors Affecting Mineral Absorption

Mineral absorption is regulated by both external and internal factors. These factors primarily include temperature, light, H+ ion concentration, oxygen concentration, ion interaction, plant development, and aging.

• Temperature: The rate of mineral absorption increases or decreases as the temperature rises or falls. In general, an increase in temperature causes an increase in salt absorption up to a certain point. Mineral absorption slows or stops entirely at extremely high temperatures. The inhibition is caused by protein denaturation, which is directly or indirectly implicated in salt absorption. Temperature also influences ion movement because active ion absorption is dependent on metabolic energy and the activity of ion carriers in the plasma membrane. At increasing temperatures, the enzymes involved in mineral absorption become inactivated

• Light: Mineral absorption is affected by metabolic energy and transpiration rate. Both transpiration and photosynthesis are controlled by light. Transpiration aids in the bulk flow of mineral ions into the cell, while photosynthesis conserves the energy required for active mineral ion absorption. As a result, a lack of light may even prevent plants from absorbing mineral ions
• H+ ion concentration: In general, a reduction in the pH of soil solution promotes anion absorption while a rise in pH favours cation absorption. However, pH values outside of the normal range can harm plant tissue and limit salt uptake

• Oxygen concentration: Mineral absorption, like many other metabolic processes, ceases to operate in the absence of oxygen. In the absence of oxygen, plant aerobic respiration ceases, and so the availability of metabolic activity diminishes. Active mineral ion absorption is impossible in the absence of metabolic energy. The availability of soil, as well as its concentration, regulates the pace of respiration and the release of metabolic energy. The rate of ion absorption falls when the oxygen content in the soil atmosphere is insufficient

• Interaction with other minerals: The absorption of one kind of ion is modified by the absorption of another type of ion. Ca++,Mg++, and other polyvalent ions influence K+ absorption. It’s most likely because of competition for binding sites on the carrier. However, in the presence of Ca++ ions, K+ and Br absorption becomes feasible. In the absorption of K, Rb, and Cs ions, there is reciprocal competition

Conclusion

Mineral absorption refers to the process of absorbing nutrients from the soil. Root hairs are extensions of the root epidermis that remain in direct touch with soil water and minerals and absorb the water at first. Plants’ Essential Elements Sources Carbon, hydrogen, and oxygen are the building blocks of macromolecules, which constitute the majority of the plant body. Active absorption refers to the movement of ions against a concentration or ECP gradient. Hogland investigated the active absorption and accumulation of ions against a concentration gradient in the green algae Nitella and Valonia by utilising energy. The cells of these algae continue to absorb K+ and phosphate ions to the point where their concentration exceeds the concentration of ions in the pond water by hundreds or thousands of times. Temperature also influences ion movement because active ion absorption is dependent on metabolic energy and the activity of ion carriers in the plasma membrane.