Question

How does soil salinity affect plant growth?

• A. Promotes optimal growth
• B. Inhibits germination and growth
• C. Has no impact on plants
• D. Increases resistance to diseases

Hint:

• High soil salinity creates a stressful environment for most plants (except halophytes).
• Osmotic effect: Reduces water uptake by roots, causing water stress.
• Specific ion toxicity: Certain ions (e.g., Na$^+$, Cl$^-$) can be directly harmful to plant cells.
• Nutrient imbalance: Interferes with the uptake of essential nutrients.
• Collectively, these lead to poor seed germination, stunted growth, reduced yields, and even plant death.

Answer 1

The Correct Option is B

To answer the question, let's explore how soil salinity affects plant growth and the mechanisms involved.

1. Understanding the Concepts:

- Soil Salinity: Soil salinity refers to the presence of dissolved salts in the soil. These salts mainly consist of sodium chloride (NaCl) but may also include other soluble salts like magnesium sulfate (MgSO₄) and calcium carbonate (CaCO₃).

- Effect of Soil Salinity on Plant Growth: High salinity in the soil can have negative effects on plant growth by affecting water uptake, nutrient availability, and physiological processes. It can disrupt the osmotic balance of plants and lead to dehydration, even when water is available in the soil.

2. Breakdown of the Given Options:

• Option 1: "Promotes optimal growth": This is incorrect. Soil salinity does not promote optimal plant growth. In fact, high salinity usually leads to poor growth conditions and reduced plant health.
• Option 2: "Inhibits germination and growth": This is the correct answer. High soil salinity inhibits seed germination and plant growth by creating osmotic stress, reducing water availability to plants, and affecting nutrient absorption. It can also lead to ion toxicity and imbalances in essential nutrients.
• Option 3: "Has no impact on plants": This is incorrect. Soil salinity has a significant impact on plants, particularly in arid and semi-arid regions where salinization can occur due to poor irrigation practices or natural salt deposits.
• Option 4: "Increases resistance to diseases": This is incorrect. Soil salinity does not increase a plant's resistance to diseases. In fact, it may weaken the plant's immune response, making it more vulnerable to diseases and pests.

3. Conclusion:

Soil salinity generally inhibits plant germination and growth. High salt concentrations in the soil create osmotic stress and ion toxicity, which hinder the plant's ability to take up water and nutrients, leading to poor growth.

Final Answer:

The correct effect of soil salinity on plant growth is that it inhibits germination and growth.