Essential Mineral Elements in Plant Nutrition

Plants absorb water, minerals, and other nutrients from the soil which is carried to the other parts of the plant by plant tissues (mostly xylem). Abundant minerals are present in the soil that are absorbed by the roots of the plants and transferred to the other parts of the plant. This is the way, all other living beings like humans and animals receive nutrients when we consume different parts of the plant. Essential mineral elements are a mix of macronutrients like calcium, phosphorus, sodium, carbon, etc. and micronutrients like iron, manganese, zinc, copper, etc. that are necessary for the growth of plants and animals.

What are Mineral Elements?

Numerous inorganic elements are essential for growth and various other life processes by humans as well as animals. Thus, these mineral elements should be necessarily taken in our diets in adequate amounts. A deficiency in any of the minerals leads to an abnormality in the metabolic functioning of the body of the organism.

As of now, approximately 105 minerals have been discovered out of which about 60 to 65 minerals are absorbed by plants from the soil. Different plant species absorb different minerals.  Some of the essential minerals required by plants for their growth and development include calcium, nitrogen, potassium, phosphorus, magnesium, sulfur, etc.

Soil is the basic medium from which almost all varieties of plants derive their essential nutrients. However, to provide more to the field of horticulture, agriculture, etc. plants are also grown on mineral nutrient media without soil.  This technique used nowadays to grow plants without soil is also known as Hydroponics. Not all minerals absorbed by plants are necessary for them, so it is important to identify the essence of minerals to different types of plants. Various techniques can be employed to do this.

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The Criteria to Determine Essential Minerals to the Plant are as follows-

• Minerals absorbed from soil by roots of plants are mineral ions dissolved in soil medium. They support plant life through their entire life cycle and also for the production of seeds.

• A few minerals like magnesium and phosphorus are crucial for the growth, development, and reproduction of plants.

• Mineral deficiency like deficiency of nitrogen, iron, copper, sulfur leads to various problems like stunted growth, poor development, insufficient chlorophyll in leaves, cell senescence, etc. in plants.

• Mineral potassium greatly influences the quality of fruits and vegetables.

• Proper metabolism in plants is dependent on minerals like potassium, sodium, magnesium, and other elements.

Essential Mineral Elements in Plants

There are two categories of minerals essential for plant growth. They are-

1. Macrominerals

Minerals like Phosphorous, carbon, sodium, nitrogen, potassium, silicon, magnesium, hydrogen, calcium, oxygen, selenium, and sulfur are required in abundance for proper plant growth and are also found abundantly in plant tissues. Therefore, they are known as macrominerals.

2. Microminerals

A few minerals like Iron, boron, nickel, manganese, copper, zinc, cobalt, chlorine, molybdenum, etc. are required in lesser quantities for proper growth by the plants and hence they are called microminerals. They are also called trace elements.

Absorption of Mineral Elements in Plants

Plants absorb the mineral elements from the soil by either of the two mechanisms-

1. Active Mineral Absorption

The type of absorption that takes place against the concentration gradient and the one which is active is known as Active transport. Active transport requires energy to take place. Inactive transport roots of the plants pick up the mineral ions and move them across the cell membrane.

2. Passive Mineral Absorption

Passive transport is a type of transport that takes place along the concentration gradient and hence it does not require energy. Transmembrane proteins act as selective pores to carry out the movement of mineral ions into the apoplast through the ion channels in this type of transport.

Functions of Mineral Elements in Plants

1. Formation of Plant Body

Various components of the plant body show the presence of various mineral elements, indicating that these elements play a vital role in the formation of the plant body. For Example- Nitrogen and sulfur make up the compound protein, iron is found in cytochromes, phosphorus in nucleic acids, and magnesium is found in chlorophyll, which is food made by plants.

2. Determining the Osmotic Potential of the Plant Cell

Osmotic potential is crucial in maintaining the turgidity of the cell and mineral elements present in the cell sap of plants determine the osmotic potential gradient.

3. Maintaining pH levels

Minerals absorbed by plants also influence the pH levels of the cell sap in plants.

4. Permeability of the Cytoplasmic Membrane

Mineral elements have cations and anions which influence the permeability of cytoplasmic membranes in plants.

5. Catalytic Effects

Bringing about the catalytic effects in the plants with the help of mineral elements such as copper, iron, zinc, etc.

6. Balancing Toxic Mineral Elements

Various mineral elements like potassium, magnesium neutralize the toxic effects of other minerals. Thus, mineral elements help to maintain the ionic balance.

7. Phloem Tissue Transport

Translocation of organic substances in the phloem tissue is carried out by elements like boron and potassium.