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By Vegetables by Bayer
» Onion types/varieties vary in their ability to withstand long-term storage.
» Pre- and post-harvest conditions and activities impact the length of time onions can be stored.
» Cool, moderately dry conditions with adequate airflow have been shown to promote longer storage durations.
Onions are one of the few vegetable crops that can tolerate long-term post-harvest storage without freezing or processing. Successful onion storage will help maintain bulb quality by minimizing moisture loss, preventing sprouting and rooting, preventing mold growth and bulb rot, and preserving the flavor and texture profile of the bulb.
ONION TYPES AND STORAGE
Onions are grouped into long-day, intermediate, and short-day types based on the daily hours of daylight required to initiate bulb formation. Long-day onion varieties require 14 to 16 hours of continuous daylight to trigger bulb formation, while short-day varieties require fewer than 12 hours. These photoperiod-based onion types generally differ in how long they can be stored. Many long-day varieties are designed for long-term storage. These varieties typically have multiple thick, dark-skinned out layers (scales) higher solids content, lose less water, are more resistant to sprouting and rooting, and can be stored for many months. Short-day varieties have thin, light-colored scales and lower solids content, and are often stored for less than thirty days. There are also some differences in storability among varieties within the different day-length groups. The rest of this article will focus on factors that affect the storability of long-day storage onions.