Mineral Nutrition – CBSE NCERT Study Resources

We studied that macronutrients (N, P, K) and micronutrients (Fe, Zn) are essential for plant growth. Macronutrients are required in large quantities, while micronutrients are needed in trace amounts.

• Nitrogen (N) is vital for protein synthesis, and its deficiency causes chlorosis.
• Iron (Fe) is a co-factor for enzymes, and its lack leads to interveinal chlorosis.

Our textbook shows that deficiencies disrupt photosynthesis and respiration. For example, potassium (K) deficiency weakens stem strength.

Understanding these roles helps in optimizing fertilizer use to improve crop yield sustainably.

The nitrogen cycle involves nitrogen fixation, nitrification, and denitrification, converting atmospheric N₂ into usable forms.

• Rhizobium bacteria fix nitrogen in legume root nodules.
• Excessive fertilizer use leads to eutrophication, disrupting aquatic ecosystems.

Our textbook shows that industrial emissions increase nitrogen oxides, causing acid rain.

Sustainable practices like crop rotation can mitigate these disruptions, ensuring soil fertility.

Active absorption requires ATP, while passive absorption occurs via diffusion or osmosis without energy.

• Active transport uses carrier proteins, e.g., uptake of K⁺ ions against concentration gradient.
• Passive absorption occurs in root hairs due to water potential differences.

Our textbook shows active absorption is dominant in mineral-rich soils, ensuring nutrient availability.

Understanding these processes aids in developing efficient irrigation and fertilization techniques.

Leghemoglobin is an oxygen-scavenging pigment in root nodules, protecting nitrogenase enzyme from O₂.

• It maintains anaerobic conditions for nitrogenase activity.
• Found in Rhizobium-legume symbiosis, e.g., soybean root nodules.

Our textbook shows that without leghemoglobin, nitrogen fixation would be inefficient due to enzyme inactivation.

Enhancing leghemoglobin production could improve crop nitrogen uptake, reducing fertilizer dependency.

Hydroponics is a soilless cultivation method where plants grow in nutrient-rich water solutions.

• Tomatoes and lettuce are commonly grown hydroponically.
• It conserves water and allows precise nutrient control.

Our textbook shows hydroponics reduces soil-borne diseases and increases yield per unit area.

This technique is vital for urban farming and regions with poor soil quality, ensuring food security.

The nitrogen cycle involves fixation, nitrification, and denitrification. Our textbook shows Rhizobium in root nodules fixes atmospheric N₂ into ammonia.

• Legume-Rhizobium symbiosis increases soil fertility.
• Industrial fixation via Haber process supplements agricultural needs.

Biological fixation reduces fertilizer dependency but is species-specific. Overuse of synthetic fertilizers disrupts aquatic ecosystems.

Genetic engineering of non-legumes for nitrogen fixation could revolutionize sustainable farming.

Passive absorption occurs via diffusion, while active absorption requires ATP. Our textbook shows proton pumps create electrochemical gradients for ion uptake.

• Potassium ion channels open in response to membrane potential.
• Proton pumps expend ATP to maintain H⁺ gradient.

Active transport dominates in nutrient-poor soils. Mutations in ion channels can stunt root development.

Enhancing proton pump efficiency could improve crop resilience in saline soils.

Micronutrients become toxic at high concentrations. Our textbook shows manganese toxicity causes necrotic spots, while excess boron inhibits root growth.

• Acidic soils (pH <5.5) increase Mn²⁺ solubility.
• Alkaline soils (pH >7.5) precipitate boron, reducing availability.

Toxicity thresholds vary by species. Rice tolerates higher Mn levels than wheat.

Soil pH monitoring and chelate therapies could mitigate toxicity in crops.

Hydroponics grows plants in nutrient solutions without soil. Our textbook shows it allows precise control over mineral composition.

• Used to study zinc deficiency symptoms in tomatoes.
• NASA employs hydroponics for space agriculture.

While costly, it eliminates soil variability. Aeroponics, a subtype, further reduces water usage.

Urban vertical farming may adopt hydroponics to combat land scarcity.

The symplastic pathway moves water through plasmodesmata, while apoplastic flow occurs via cell walls. Our textbook shows casparian strips in endodermis block apoplastic flow.

• Dyes like berberine trace apoplastic route.
• Aquaporins facilitate symplastic water transport.

Casparian strips force selective absorption, preventing toxin entry. Drought-resistant plants exhibit thicker strips.

Engineering casparian strip composition could enhance crop salt tolerance.

Macronutrients and micronutrients are essential for plant growth and development, but they are required in different quantities. Macronutrients like nitrogen (N), phosphorus (P), and potassium (K) are needed in larger amounts for processes such as protein synthesis, energy transfer, and enzyme activation. For example, nitrogen is a key component of chlorophyll, while phosphorus is vital for ATP formation.

On the other hand, micronutrients like iron (Fe), zinc (Zn), and manganese (Mn) are required in trace amounts but are equally important. Iron, for instance, is crucial for chlorophyll synthesis, and zinc aids in auxin production.

Deficiency of these nutrients leads to specific symptoms:

• Nitrogen deficiency causes yellowing of leaves (chlorosis).
• Iron deficiency results in interveinal chlorosis in young leaves.
• Potassium deficiency leads to weak stems and brown leaf margins.

Biological nitrogen fixation is the process by which atmospheric nitrogen (N₂) is converted into ammonia (NH₃) by certain microorganisms. This process is crucial for making nitrogen available to plants.

The bacteria involved are Rhizobium, which form a symbiotic relationship with leguminous plants like peas and beans. Here’s how it works:
1. Rhizobium bacteria infect the root hairs of the host plant, forming root nodules.
2. Inside the nodules, the bacteria convert N₂ into NH₃ using the enzyme nitrogenase.
3. The plant provides the bacteria with carbohydrates and a protective environment.
4. In return, the bacteria supply the plant with fixed nitrogen for amino acid and protein synthesis.

This mutualistic relationship enhances soil fertility and reduces the need for chemical fertilizers.

Autotrophic nutrition and heterotrophic nutrition are two distinct modes of nutrition in plants:

Autotrophic Nutrition:
- Plants synthesize their own food using sunlight, water, and CO₂ via photosynthesis.
- Example: Green plants like wheat and rice.
- Significance: They form the base of the food chain and produce oxygen.

Heterotrophic Nutrition:
- Plants depend on other organisms for food.
- Examples:

• Parasitic plants (e.g., Cuscuta) derive nutrients from host plants.
• Insectivorous plants (e.g., Venus flytrap) trap insects for nitrogen.

While autotrophs are primary producers, heterotrophs play specialized roles in nutrient cycling.

Hydroponics is a soil-less method of growing plants using mineral nutrient solutions in water. Here’s how it works:
1. Plants are placed in an inert medium like gravel or perlite.
2. A nutrient-rich solution is circulated around the roots to provide essential minerals.
3. Oxygen is supplied to roots through aeration.

Advantages:

• Higher yield due to controlled nutrient supply.
• Water-efficient as it reduces wastage.
• No soil-borne diseases or weeds.
• Suitable for urban farming and space-limited areas.

Limitations:

• High initial setup cost.
• Requires constant monitoring of pH and nutrients.
• Dependent on electricity for pumps and lights.

Despite limitations, hydroponics is a promising technique for sustainable agriculture, especially in regions with poor soil quality.

Macronutrients and micronutrients are essential for plant growth and development, but they are required in different quantities. Macronutrients are needed in larger amounts, while micronutrients are required in trace amounts.

Macronutrients include elements like nitrogen (N), phosphorus (P), and potassium (K). These play vital roles:

• Nitrogen: Key component of amino acids, proteins, and chlorophyll, essential for photosynthesis.
• Phosphorus: Important for energy transfer (ATP) and nucleic acid synthesis.
• Potassium: Regulates stomatal opening and enzyme activation.

Micronutrients include elements like iron (Fe), zinc (Zn), and manganese (Mn). Their functions are:

• Iron: Essential for chlorophyll synthesis and electron transport.
• Zinc: Acts as a cofactor for enzymes and aids in auxin synthesis.
• Manganese: Involved in photosystem II and nitrogen metabolism.

Both types of nutrients are crucial for maintaining plant health, and their deficiency can lead to specific symptoms like chlorosis or stunted growth.

Biological nitrogen fixation is the process by which atmospheric nitrogen (N₂) is converted into ammonia (NH₃) by microorganisms like Rhizobium, which forms symbiotic associations with leguminous plants.

The steps involved are:

1. Infection: Rhizobium bacteria infect the root hairs of the host plant, leading to the formation of an infection thread.
2. Nodule Formation: The bacteria multiply within the root cells, stimulating the plant to form root nodules.
3. Nitrogenase Activity: Inside the nodules, the enzyme nitrogenase (present in bacteria) converts N₂ into NH₃ in the presence of ATP and reducing agents.
4. Ammonia Assimilation: The ammonia is then assimilated into amino acids like glutamine and asparagine, which are used by the plant.

This process is crucial for enriching soil fertility, as it provides a natural source of nitrogen for plants without the need for chemical fertilizers.

Deficiency symptoms of essential nutrients like nitrogen, phosphorus, and potassium manifest in distinct ways, aiding in their diagnosis:

• Nitrogen (N) Deficiency:
  Leaves turn yellow (chlorosis), starting with older leaves due to reduced chlorophyll synthesis.
  Stunted growth and delayed maturity occur due to impaired protein formation.
• Phosphorus (P) Deficiency:
  Leaves develop a dark green or purplish hue due to anthocyanin accumulation.
  Root growth is inhibited, and flowering/fruiting is delayed.
• Potassium (K) Deficiency:
  Leaves show scorching or necrosis at margins and tips.
  Weak stems and poor disease resistance are observed due to disrupted enzyme function.

These symptoms help farmers and agronomists identify nutrient deficiencies early, allowing for timely corrective measures like fertilization or soil amendments. Observing the specific patterns (e.g., chlorosis in nitrogen deficiency) ensures accurate diagnosis and treatment.

Macronutrients and micronutrients are essential for plant growth and development, but they are required in different quantities. Macronutrients are needed in larger amounts, while micronutrients are required in trace amounts.

Macronutrients:
1. Nitrogen (N): Key component of amino acids, proteins, and chlorophyll. Deficiency causes chlorosis (yellowing of leaves).
2. Phosphorus (P): Vital for ATP, nucleic acids, and cell membranes. Deficiency leads to stunted growth.
3. Potassium (K): Regulates stomatal opening and enzyme activation. Deficiency causes weak stems and leaf edges turning brown.

Micronutrients:
1. Iron (Fe): Essential for chlorophyll synthesis and electron transport. Deficiency results in interveinal chlorosis.
2. Zinc (Zn): Activates enzymes and aids in auxin synthesis. Deficiency causes stunted leaves (little leaf syndrome).
3. Manganese (Mn): Involved in photosynthesis and nitrogen metabolism. Deficiency leads to yellow spots on leaves.

Both types of nutrients work together to ensure healthy plant growth, with macronutrients supporting structural and metabolic functions, while micronutrients act as cofactors for enzymes and other biochemical processes.

Biological nitrogen fixation is the conversion of atmospheric nitrogen (N₂) into ammonia (NH₃) by microorganisms, primarily Rhizobium bacteria in symbiotic association with leguminous plants.

Process:
1. Rhizobium bacteria infect the root hairs of legumes, forming root nodules.
2. Inside the nodules, bacteria convert N₂ to NH₃ using the enzyme nitrogenase.
3. The plant provides carbohydrates and a low-oxygen environment for the bacteria.
4. The fixed nitrogen is assimilated into amino acids and other organic compounds for plant use.

Benefits to Agriculture:
1. Reduces dependency on chemical fertilizers, lowering costs.
2. Improves soil fertility by increasing nitrogen content naturally.
3. Enhances crop yield and sustainability in farming systems.
4. Prevents environmental pollution caused by synthetic fertilizers.

This symbiotic relationship is crucial for sustainable agriculture, as it maintains soil health and supports eco-friendly farming practices.

Micronutrients are essential elements required by plants in small quantities but play a crucial role in various physiological and biochemical processes. They act as co-factors for enzymes, participate in redox reactions, and contribute to the structural integrity of cells.

The importance of zinc and manganese in plant growth is as follows:

• Zinc (Zn): It is vital for the synthesis of auxins, a plant growth hormone, and is a component of enzymes like carbonic anhydrase and alcohol dehydrogenase. Zinc deficiency leads to stunted growth and interveinal chlorosis in leaves. For example, in rice, zinc deficiency causes khaira disease, leading to reduced yield.
• Manganese (Mn): It plays a key role in photosynthesis by splitting water molecules during the light reaction and is a co-factor for enzymes like nitrate reductase. Manganese deficiency results in chlorosis and necrotic spots on leaves. For instance, in oats, manganese deficiency causes grey speck disease.

Both zinc and manganese are critical for maintaining plant health, and their deficiency can severely impact crop productivity. Proper soil management and fertilization are necessary to ensure their availability for optimal plant growth.