Storage of onions

In Maharashtra, Gujarat, Haryana and Western Uttar Pradesh large-scale storage of onions is taken in conventionally-designed structures. In other states, the storage is taken only on small scale but now showing increasing trend after the post-harvest technology and improved storage structures have been popularized by NHRDF.Traditional storage practices result in substantial losses in stored onions, hence use of improved storage structures as well as use of good storer varieties, judicious use of fertilizers, timely irrigation and post-harvest technology are essential to reduce the losses in stored onions.

Storage temperature and humidity affect loss in weight, respiration rate, sprouting, rotting and quality of bulbs in storage. The dormancy in onion bulbs is the main factor to determine as how long the bulbs can be stored. Inherent characters of dormancy based on equilibrium of inhibitors in onion bulbs also gets affected by temperature where lower (0⁰C) and higher (30⁰C) temperature increase the dormant state of onion bulbs and moderate (10-15⁰C) temperature enhance the sprouting losses by breaking dormancy. Higher temperature, however, increases the rottage if accompanied with high humidity and desiccation/water loss is reduced at higher humidity but it increase the rooting and rotting. Hence equilibrium of temperature and relative humidity by providing sufficient aeration/ventilation is needed in improved onion store houses.