What is Mineral Nutrition?
Mineral Nutrition is known as a naturally occurring inorganic nutrient. It can be found in the soil and food and it is vital for the able functioning of animal and plant bodies. Minerals are the vital elements which allow a body to grow and to survive. Minerals are essentially needed by both plants and animals. For example zinc is needed for cell division and for the production of protein.
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Role of Nutrients
Following are listed some important roles that nutrients play:-
Balancing Function: Some salts or minerals act against the harmful effects of the other nutrients hence balance the effect of each other.
Maintenance of Osmotic Pressure: In few minerals the cell sap is present in organic or inorganic form, to control the organic pressure of the cell.
Influencing The pH of The Cell Sap: Different anions and cations have different influences on the pH of the cell sap.
Construction of The Plant Body: Some of the elements which help to construct the plant body are Carbon, Nitrogen and Oxygen. They help by entering the protoplasm and constitution of the wall.
Catalysis of The Biochemical Reaction: Zinc, magnesium, calcium, and copper act as metallic catalysts in biochemical reactions.
Effects of Toxicity: Under specific conditions, minerals like arsenic and copper have a toxic effect on the protoplasm.
Micronutrients
Micronutrients are the nutrients required by plants in very small proportions. Some of them are Boron, iron, chlorine, and molybdenum are some of the examples of micronutrients.
Importance of Micronutrients
Following are listed some important functions of micronutrients in particular:-
Copper
It is responsible for activating the enzymes as a component of oxidase, cytochrome oxidase, phenolases, and ascorbic acid oxidase.
It as well plays a vital role in photophosphorylation.
Copper helps to balance carbohydrate-nitrogen regulation.
Manganese
It is required in photosynthesis.
Manganese is needed in the synthesis of chlorophyll.
It also acts as an activator of nitrogen metabolism.
Zinc
It is essentially required for the synthesis of tryptophan, metabolism of carbohydrates,
and phosphorus.
Zinc is a constituent of enzymes like alcohol dehydrate-gas, carbonic anhydrase, lactic dehydrogenase, hexokinase, and carboxypeptidase.
Macronutrients
Macronutrients are the nutrients required by plants in larger proportions. These may include sulfur, nitrogen, carbon, phosphorus, calcium, potassium, and magnesium.
Importance of Macronutrients
Following are some of the vital functions performed by macronutrients in particular:-
Phosphorous
Phosphorus helps to boost the process of fruit ripening and root growth in a healthy manner by helping the translocation of carbohydrates.
Phosphorus is found abundantly in fruits and seeds.
Premature fall of leaves and colour turning to purplish or dark green is due to deficiency of phosphorus.
Nitrogen
Nitrogen is present in various coenzymes, hormones, and ATP, etc.
It is a vital constituent of vitamins, nucleic acids, proteins, and many others.
The complete suppression of flowering and fruiting, impaired growth, and development of anthocyanin pigmentation in stems is due to deficiency of nitrogen.
Potassium
Potassium is the only monovalent cation that is necessary for plants which acts as an enzyme activator including DNA polymerase. The deficiency of potassium leads to Mottled chlorosis.
Following are the important difference between macronutrients and micronutrients:-
Difference between Micronutrients and Macronutrients
Did you know?!
Milk is 87% water. The nutrients, like protein, carbohydrate, vitamins, and minerals are all found in the other 13%.
FAQs on Mineral Nutrition
1. What is mineral nutrition in the context of plant biology?
Mineral nutrition is the study of how plants obtain and utilise essential inorganic nutrients from their environment, primarily the soil, for their growth, development, and physiological functions. It focuses on identifying which elements are essential, their specific roles within the plant, and the effects of their absence or excess.
2. What is the primary difference between macronutrients and micronutrients for plants?
The primary difference lies in the quantity required by the plant. Macronutrients are elements needed in relatively large amounts (generally >10 mmole kg⁻¹ of dry matter), such as Carbon, Nitrogen, and Phosphorus. In contrast, micronutrients, or trace elements, are required in very small quantities (generally <10 mmole kg⁻¹ of dry matter), such as Iron, Manganese, and Zinc. Both are equally essential for the plant's survival.
3. What are the main roles of Nitrogen, Phosphorus, and Potassium (NPK) in plants?
Nitrogen, Phosphorus, and Potassium (NPK) are three of the most critical macronutrients. Their roles include:
- Nitrogen (N): A major constituent of proteins, nucleic acids (DNA, RNA), vitamins, and hormones. It is essential for metabolic activity and vegetative growth.
- Phosphorus (P): A key component of cell membranes, certain proteins, all nucleic acids, and energy-carrying molecules like ATP (Adenosine Triphosphate). It is vital for energy transfer reactions.
- Potassium (K): Required in abundance in meristematic tissues, buds, leaves, and root tips. It helps maintain cell turgidity and acts as an activator for many crucial enzymes involved in photosynthesis and respiration.
4. What is hydroponics, and why is it important for studying mineral nutrition?
Hydroponics is a technique for growing plants in a soilless medium, using a precisely controlled nutrient solution containing all essential elements. This method is crucial for nutritional studies because it allows researchers to:
- Determine the absolute essentiality of a mineral element for a plant.
- Identify the specific deficiency symptoms that appear when an essential element is absent.
- Study the effects of mineral toxicity by systematically increasing an element's concentration.
5. Why is Nitrogen often a limiting factor for plant growth, even though it makes up 78% of the atmosphere?
Although abundant, atmospheric nitrogen (N₂) exists in a highly stable form with a strong triple bond between its two atoms, making it unusable by plants directly. Plants can only absorb nitrogen in the form of nitrate (NO₃⁻) or ammonium (NH₄⁺) from the soil. The conversion of atmospheric N₂ into these usable forms, a process called nitrogen fixation, is slow and primarily done by specialised microorganisms.
6. How can an excess of one essential mineral lead to a deficiency of another?
This phenomenon is known as mineral toxicity or antagonism. An excess concentration of one element can interfere with the uptake and activity of another. For example, an excess of Manganese (Mn) can compete with Iron (Fe) and Magnesium (Mg) for uptake by the plant's roots. It also inhibits the translocation of Calcium (Ca) to the shoot apex. Therefore, symptoms of manganese toxicity can often appear as deficiencies of iron, magnesium, and calcium.
7. What is the difference between chlorosis and necrosis as plant deficiency symptoms?
Both are visible signs of nutrient deficiency, but they describe different effects on plant tissue. Chlorosis is the loss of chlorophyll, resulting in the yellowing of leaves. It is commonly caused by a deficiency of elements like Nitrogen, Potassium, Magnesium, and Iron. Necrosis, on the other hand, is the localised death of plant tissue, often appearing as dead spots or patches on leaves, stems, or flowers. It is typically caused by a deficiency of Calcium, Magnesium, Copper, or Potassium.
8. Beyond being building blocks, how do minerals function as enzyme activators in plants?
Many minerals act as crucial cofactors or activators for enzymes, enabling key metabolic reactions. For instance, Magnesium (Mg²⁺) is an activator for both RuBisCO and PEPCase, two critical enzymes in photosynthesis. Zinc (Zn²⁺) is an activator of alcohol dehydrogenase, while Molybdenum (Mo) is a component of nitrogenase, the enzyme responsible for nitrogen fixation. These minerals bind to the enzyme, changing its structure to an active state, thus allowing the biochemical reaction to proceed.
9. What are the criteria for an element to be considered essential for a plant?
According to Arnon and Stout's criteria of essentiality, an element must meet the following three conditions:
- The plant must be unable to complete its life cycle (i.e., grow and reproduce) in the absence of the element.
- The function of the element must be specific and not replaceable by another element.
- The element must be directly involved in the plant's metabolism, for example, as a component of an essential molecule or an enzyme cofactor.
10. What is biological nitrogen fixation and which organisms perform it?
Biological nitrogen fixation is the process where atmospheric nitrogen (N₂) is converted into ammonia (NH₃) by living organisms. This is the primary way nitrogen enters the biosphere in a usable form. This critical process is carried out by a select group of prokaryotes, including:
- Symbiotic bacteria, such as Rhizobium, which form nodules on the roots of leguminous plants.
- Free-living bacteria in the soil, such as Azotobacter and Beijerinckia (aerobic) and Rhodospirillum (anaerobic).
- Cyanobacteria (blue-green algae), such as Anabaena and Nostoc.
