Which nutrient element imparts indirect drought resistance?

Correct option is A

The correct answer is (A) K

Explanation:
• Potassium (K) is well-known for providing drought resistance to plants through several physiological mechanisms.
• It regulates the opening and closing of stomata (pores on the leaf surface). Proper stomatal control allows the plant to reduce water loss through transpiration during dry periods.
• It increases the osmotic potential of cells, helping the plant maintain turgor pressure even when water is scarce.
• It also promotes root growth, allowing the plant to tap into deeper water sources in the soil. Because it helps the plant adapt to water stress without directly being a part of the water molecule itself, it is often described as imparting indirect drought resistance.

Information Booster:
• Potassium is the only macronutrient that does not become a structural part of plant molecules (like proteins or chlorophyll); it remains in the ionic form ($K^+$) within the cell sap.
• It is involved in activating over $60$ enzymes in plants.
• Luxury consumption is a term associated with Potassium, where plants take up more K than they need for growth if it is available.

Additional Knowledge:
• Calcium (Ca) (Option B): Essential for cell wall structure and cell division; it acts as a secondary messenger in stress signaling.
• Magnesium (Mg) (Option C): The central atom of the chlorophyll molecule, essential for photosynthesis.
• Sulphur (S) (Option D): Essential for the synthesis of amino acids like methionine and cysteine and for oil production in oilseed crops.