Question

Which nutrient deficiency causes yellowing of leaves in plants?

• A. Nitrogen
• B. Potassium
• C. Phosphorus
• D. Calcium

Hint:

Yellowing of leaves caused by lack of chlorophyll is called chlorosis. The most common nutrient responsible for this condition is nitrogen.

Answer 1

The Correct Option is A

Step 1: Importance of nutrients in plants.
Plants require essential nutrients for proper growth, development, and metabolism. These nutrients are categorized into macronutrients and micronutrients. Macronutrients such as nitrogen, phosphorus, and potassium are required in larger quantities and play major roles in plant physiology.
Step 2: Role of nitrogen in plants.
Nitrogen is a crucial nutrient because it forms an important part of chlorophyll, the green pigment responsible for photosynthesis. It also helps in the formation of proteins, enzymes, and nucleic acids that support plant growth.
Step 3: Effect of nitrogen deficiency.
When plants suffer from nitrogen deficiency, they are unable to synthesize sufficient chlorophyll. As a result, the leaves lose their green color and gradually turn yellow. This condition is known as chlorosis and it usually begins in older leaves before spreading to other parts of the plant.
Step 4: Comparison with other options.

• (A) Nitrogen: Correct. Lack of nitrogen causes chlorosis which results in yellowing of leaves.
  
• (B) Potassium: Potassium deficiency generally causes scorching or burning of leaf edges rather than yellowing of the entire leaf.
  
• (C) Phosphorus: Phosphorus deficiency often leads to dark green or purplish coloration of leaves.
  
• (D) Calcium: Calcium deficiency mainly affects growing points and young tissues rather than causing general yellowing.
  

Step 5: Conclusion.
Since nitrogen is essential for chlorophyll production, its deficiency results in yellowing of leaves in plants. Final Answer:} Nitrogen.