JB_Inorganic_Nutrients_are_Essential_for_Plants

Principle 5: Inorganic Nutrients for Plants

• Inorganic nutrients are essential for plant growth and reproduction.

Expected Outcomes

1. Describe inorganic nutrients needed for plant growth.

2. Understand the role of macro and micronutrients.

3. Explain how plants obtain nutrients from the soil.

Essential Nutrients

• Required for Normal Growth and Reproduction

  • Essential nutrients are indispensable, with no replacements, and their absence leads to deficiency symptoms.

  • They play significant roles in plant metabolism.

Sources of Essential Nutrients

• Air and Water Sources:

  • Oxygen (O2) and Hydrogen (H2O): From water.

  • Carbon (CO2): From the atmosphere.

• Soil Sources (Mineral Nutrients):

  • Macronutrients: Required in larger quantities (e.g., Nitrogen, Phosphorus).

  • Micronutrients: Required in smaller quantities (e.g., Iron, Manganese).

Proportional Weights in Plants

• Carbon, hydrogen, and oxygen comprise 96% of plant composition.

• Macronutrients constitute 3.5%

• Micronutrients account for 0.5%.

• Notable macronutrients include Nitrogen, Phosphorus, and Potassium.

Impact of Nutrient Availability on Growth

• Nutrient imbalances can significantly affect plant growth.

• Growth is maximized in the adequate zone of nutrient concentration; too little or too much leads to deficiency or toxicity, respectively.

Review of Root Structures

• Identify the roots' structures (endodermis, pericycle, cortex) responsible for ion regulation.

Macronutrients Breakdown

• Macronutrients (% dry weight):

  • Nitrogen (N): 1.5% - Forms: NO3-, NH4+; Functions: DNA, proteins, chlorophyll.

  • Potassium (K): 1.0% - Forms: K+; Functions: Stomatal regulation, enzyme activation.

  • Phosphorus (P): 0.2% - Forms: HPO4^2-, H2PO4-; Functions: Energy transfer (ATP), DNA.

  • Calcium (Ca): 0.5% - Forms: Ca^2+; Functions: Cell wall structure.

  • Magnesium (Mg): 0.2% - Forms: Mg^2+; Functions: Chlorophyll synthesis.

  • Sulfur (S): 0.1% - Forms: SO4^2-; Functions: Protein synthesis.

Micronutrients Breakdown

• Micronutrients (% dry weight):

  • Iron (Fe): 0.01% - Functions: Chlorophyll synthesis.

  • Chlorine (Cl): 0.01% - Functions: Water splitting, turgor regulation.

  • Boron (B): 0.002% - Functions: Sugar transport, cell division.

  • Zinc (Zn): 0.002% - Functions: Chlorophyll synthesis.

  • Copper (Cu): 0.0006% - Functions: Enzyme component.

  • Molybdenum (Mo): 0.00001% - Functions: Nitrogen fixation.

Symptoms of Nutrient Deficiencies

• Nutrient deficiencies can lead to abnormal growth and coloration:

  • Sulfur (S): Chlorosis in young leaves.

  • Boron (B): Necrosis in growing points (meristems).

  • Manganese (Mn) & Iron (Fe): Interveinal chlorosis in older leaves.

  • Magnesium (Mg): Interveinal chlorosis.

  • Nitrogen (N): General chlorosis.

  • Phosphorus (P): Red discoloration; Potassium (K): Leaf margin necrosis.

Nutrient Mobility and Effect on Deficiency Symptoms

• Mobile Nutrients: N, P, K, Mg, Cl - Show deficiencies in old leaves.

• Immobile Nutrients: Ca, B, Fe - Show deficiencies in young tissues.

Understanding Copper Deficiency

• Copper deficiency results in poor growth across all plant tissues, demonstrating the importance of this micronutrient.

Soil Properties and Mineral Availability

• Soil can dissolve minerals or bind them to particles, affecting how nutrients are acquired by plants.

Soil Texture and Water Drainage

• Soil particle size influences water drainage capacity:

  • Sand: 0.05 - 2mm

  • Silt: 0.002 - 0.05mm

  • Clay: <0.002mm

Anion and Cation Exchange Features

• Cation Exchange: Helps plants absorb nutrients bound to soil particles by releasing them into the soil solution.

• Factors Affecting CEC: Soil pH, clay amount, organic material.

Impact of Acid Rain on Soil Properties

• Acid rain alters soil conditions affecting H+ levels and cation exchange capacity, influencing overall tree growth rates.

Importance of High CEC Soils

• Soils with high cation exchange capacity facilitate nutrient availability and enhance plant growth and productivity.

Nutrient Absorption Pathways

• After absorption by root hairs, nutrients travel to vascular tissue via three primary routes: apoplastic, symplastic, and transmembrane routes, with the Casparian strip blocking the apoplastic route.

Ion Movement Across Plant Cell Membranes

• Proton pumps create an electrochemical gradient, allowing for the entrance of cations through channels and anions via cotransporters.

• Any ions without transporters can become trapped in the apoplast.