Mechanisms behind the post harvest sprouting of onions (allium cepa) and future implications of prevention strategies

Globally, onions are an important vegetables used primarily as a flavoring agents. Onion Bulbs has three major stage in physiology viz rest, dormancy and sprout. During post harvest storage sprouting is the major problem that causes loss of onions. The sprouting in bulbs controlled by different factors such as concentration of plant hormones, biochemical and molecular changes. Therefore, control of sprouting in onion bulbs is commercially crucial for shelf life management. At present, technologies like maleic hydrazide, 1-methyl cyclopropane, γ-radiation, and ozone used to prevent onion sprouting but these technologies have some negative impact on health so need to explore alternative prevention strategies. Recently, the role of various plant hormones in sprout initiation, elongation, and development in onions during storage was emerged. In this review, emphasized on onion physiology, hormonal genes associated with dormancy, and factor affecting the sprouting. Also, summarized the mechanism, physico-chemical changes and prevention strategies in onion bulbs during sprouting.