Khaira disease of rice is caused due to the deficiency of

The correct option is B

Zinc deficiency

The correct option is B.

Explanation for correct option:

1. Khaira disease is a common disease in rice caused to zinc deficiency.
2. It leads to the formation of dusty brown patches on leaves and causes necrosis.
3. It is observed in rice crops grown in calcareous soil.

Explanation for incorrect option:

Option A:

Boron deficiency in rice occurs rarely. It occurs in highly weathered and acid soils.

Option C:

Magnesium deficiency causes chlorosis between the leaf ribs and leads to necrosis.

Option D:

It is an incorrect option as only one option is correct.

Final answer: Khaira disease of rice is caused due to the deficiency of zinc.