Harvesting and Seed preservation of Onion

Harvesting and Seed preservation of Onion

In onion, neckfall is the indication of maturity for bulb. Time of harvest depends on

several factors such as planting season, cultivar, market price, conditions of the crop

etc. The duration of the crop is usually 5.5 and 3.5 months for rabi and kharif season,

respectively. If onions are grown by direct seeding method, the crop is ready for

about 20-25 days earlier than the transplanted ones. When the bulbs mature, the green

tops become weaken and fall down that is called neckfall. When neckfall begins,

irrigarion is to be stopped. In general, when more than 50% neckfall is found, the

bulbs are harvested along with leaves by hand-pulling. The harvested plants with

bulbs are allowed to cure for about 7 days. After complete curing, the roots and tops

are clipped. The leaves are cut leaving about 2.25 cm tops above the bulbs. Curing is

the drying of neck, root and outer scale tissue to remove excess moisture from them.

It is essential to prevent disease infection, shrinkage and development of bad colour

in bulb.

Bulb storage

The harvested bulbs are usually stored both for human consumption throughout the

year and for growing seeds in the next year. Storage techniques and storage

conditions have great impact on the shelf life of onion. Proper storage is crucial for

retaining bulb quality. Factors influencing storage bulbs are variety, growing season,

harvesting stage, curing, fertilizer and irrigation application, storage techniques,

storage conditions, temperature and humidity etc. Early harvesting results in

sprouting of bulbs while late harvesting results in formation of secondary roots

during storage. Thick-neck bulbs resulting from premature harvesting also do not

store well. The bulbs should be graded according to size and quality. Cool, dry and

well ventilated store room will keep onion bulbs in good conditions for many

months. On average, the storage loss of onion bulb may be 45-60% due to

respiration weight loss, rotting of bulb and sprouting. This storage loss can be

minimized by selection of suitable varieties with long shelf life, efficient irrigation

management, balanced fertilization, optimum time of planting, proper harvesting

time and improved storage. In cold storage, onion can be stored nearly for 10-12

months with temperature 0-5ºC and relative humidity 60%. The rabi (winter) onion

store well than the kharif ones.