- A Nitrogen
- B Potassium
- C Calcium
- D Magnesium
Correct answer: C. Calcium
Explanation: Blossom end rot of tomatoes is caused by calcium deficiency in the developing fruit. Calcium is poorly mobile in plants; irregular watering disrupts Ca transport. Affected tissue becomes dark, leathery, and sunken at the flower end.
Concept context
Essential mineral elements, their roles and deficiency symptoms. Nitrogen fixation and soil nutrition.