Question

Onion should be stored at a relative humidity of

• A. 65-75 %
• B. 75-85 %
• C. 85-95 %
• D. 95-98 %

Hint:

Onions and garlic require low relative humidity ($65\text{--}75\%$) to maintain dry outer papery scales and prevent fungal decay.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Storage relative humidity (RH) requirements vary significantly across horticultural produce depending on surface curing and dormant physiology.

Step 2: Detailed Explanation:
Unlike most fresh leafy vegetables and succulent fruits that require high humidity ($90\text{--}95\%$ RH), cured bulb onions must be stored at a lower RH of $65\text{--}75\%$ (at $0\text{--}2^\circ\text{C}$ or well-ventilated dry conditions).
Relative humidity levels exceeding $75\text{--}80\%$ promote fungal neck rot (Botrytis allii), black mould (Aspergillus niger), root emergence, and premature sprouting.

Step 3: Final Answer:
Therefore, onions should be stored at a relative humidity of 65-75%.