Onion

(Allium cepa)
The onion is a hardy cool-season biennial but usually grown as annual crop. The onion has
narrow, hollow leaves and a base which enlarges to form a bulb. The bulb can be white,
yellow, or red and require 80 to 150 days to reach harvest.

Climate

Onions are temperature sensitive. They require cool weather to produce their tops and warm
weather to produce their bulbs. However, crop can be grown well under mild climate. In
areas where average annual rainfall exceeds 75-100cm in the monsoon periods, it can be
grown only as a summer crop. Temperature ranging from 12.80C-230C before bulbing and
200C -250C for bulb development is considered ideal. Most onions are sensitive to day
length.

Soil

Onion can be grown on all types of soils. Green onions can be grown in a partially shady
spot. However, deep friable loam (6 inches) and alluvial soils are best for successful
cultivation. It is sensitive to high acidity and produces a maximum yield over a narrow range
of soil reaction. The optimum range of soil pH is between 5.8 and 6.5.

Varieties

Pusa White Flat: Bulbs are medium large, flattish round with attractive white colour, 12-
14%TSS and good keeping quality. This variety has yield potential of 300-325q/ha with crop
duration of 120-130 days.

Pusa White Round: Bulbs medium in size, roundish with attractive white colour, 12-
14%TSS and good keeping quality. This variety has yield potential of 300-325q/ha with crop
duration of 125-130 days after transplanting.

Pusa Ratnar: Plants are 30cm tall and dark green leaves with waxy bloom. Bulbs are
bronze deep red, obviate to flat globular, less pungent with 12% TSS and good keeping
quality. This variety has yield potential of 325-350q/ha with crop duration of 150 days.

Pusa Red: Plants 55-65cm tall with 6-9leaves/plant, bulb yield of 25-40t/ha in 125-140 days
of transplanting.

Agrifound Light Red: Bulbs are light red, globular, tight skinned 4-6cm in size, 12-13%TSS,
good keeping quality, bulb yield of 300-325q/ha bulb yield in 110-120days of transplanting.

Agrifound Dark Red: Bulbs are dark red, globular 4-6cm size moderately pungent with12-
13% TSS, average keeping quality, gives 300q/ha bulb yield in 95-110 days of transplanting.

N-53: Bulbs are shinny red, globular in shape less pungent, TSS 11-12% poor storage
capacity, gives yield of 150-200q/ha, suitable for Kharif season.

NHRDF-Red (L-28): Bulbs are attractive dark red in colour and 4.5-6.0cm in diameter.TSS
13-14%, yield is 250-300q/ha, maturity in 110-120 days after transplanting.
 Hisar-2: Bulbs are bronze red in colour, flattish globular in shape, more pungent, better shelf
life. Average yield 200-250q/ha.

Sowing time

Zone Sowing Transplanting

Sub-tropical Oct- Nov Dec.-Jan
Intermediate August October
Sowing method

Onions can be grown from seeds and sets. In the first method, about 10-12kg seeds are
sown to raise seedlings for one hectare and area wise about 5% area is required to raise
seedlings for one hectare. The seeds after treatment with thiram or captan (2-3g/kg seed)
are sown in raised (15-20cm) nursery beds of 3mx0.6m size with a distance of 70cm
between the beds. Seeds are sown in lines 4-5cm apart and not more than 2-3cm deep.
After sowing beds are mulched with straw, dry grass or any such material to preserve the
soil moisture. Light irrigation should be provided after two days of sowing and later as and
when required. Once the seeds have germinated, the mulch material should be removed. 8-
9weeks old seedlings i.e., 50-55 days of sowing are ready for transplanting at spacing of
15cm x 10cm, totalling 70-80 plants per sqm. Sets are small bulblets--about large pea size
and developed from the seedlings in the nursery bed. These seedlings are not transplanted
but retained in the beds till small pea size bulblets are formed i.e., after 3.0-3.5 months of
sowing. These are best used as propagating material for kharif onion. Sets are planted just
below the soil surface and are quick to begin growing. (But there are fewer onion varieties
available as sets)

Manures and fertilizers

FYM (t/ha) N(Urea) P2O5 (DAP) K20 (MOP)kg/ha

20 100 (200.0) 50 (110.0) 50 (85.0)
Full dose of well rotten farmyard manure should be well applied to the field, one month
before transplanting. Full dose of phosphorous and potash and half dose of nitrogen should
be applied before transplanting and remaining dose of nitrogen is top dressed after about a
month after transplanting (i.e., before initiation of bulbs)

Intercultural operations

Keep the beds free of weeds to avoid competition for light, water, and nutrients. Onion is
shallow rooted crop, so very shallow culture operation should be followed. Chemicals can
profitably be used for Control measures of weeds. Application of stomp 30EC @ 2.5litres/ha
or Basalin@ 1.0 litre /ha immediately after transplanting or before first irrigation followed by
one hand weeding after 45 days can check the weeds effectively.

Irrigation

One light irrigation is given immediately after transplanting for proper establishment of
seedlings. Subsequent irrigations should be provided at 7-10days interval. In all, 15-20
irrigations are required. The most important stage of irrigation is the bulb formation and
enlargement stage. The negligence at this stage results in cracking of the bulbs and low
yield. Frequent irrigations delay maturity.
Harvesting

In onion, neckfall is the indication of maturity. Onion becomes ready for harvesting in 5-6
months after transplanting for dry onion (after 25-50% neck fall). The secondary bulbs
developing from other bulbs, 2-3 months after transplanting, find a ready market as green
onions, early in the season (October-December).Lift dry onion bulbs when they are 3 to 5
inches in diameter after the leaves have dried.

Curing

In rabi season, keep bulbs in the field for 3-5days and then cut the pseudostem2-5cm above
the bulb and dry them in shade for 7-10days.It will remove the excess moisture from the
outer skin and neck. Onions are considered cured when neck is tight and the outer scales
are dried.

Storage

Bulbs can be stored under well ventilated storage structures with low temperature (2.90C to
29.4 0C) and dry condition for 5-6months without sprouting and without excessive loss of
weight.

Yield

Big sized onion (5.5cm and above):250-300q/ha

Small and medium sized onions (<5.5cm) : 160-200q/ha.

Onion seed production

Onion is biennial plant and requires two seasons to complete its cycle. In first year, bulbs are
raised from seed and in second year, these mother bulbs are planted at 45 x 20 cm distance
in October and crop is ready in April/May. Land should be free from volunteer plants.

Isolation distance

For mother bulb production, isolation distance of 5meter is required from fields of other
varieties and same variety not conforming to varietal purity. To maintain varietal
characteristics, two inspections- one after transplanting and second after bulbs have been
lifted should be done. In seed production minimum isolation distance of 1000 and 500
meters for foundation and certified seed respectively must be kept.

Inspections

A minimum of four inspections, first before flowering, second and third during flowering and
fourth at maturity are required.

Seed yield

An average yield of 1000 – 1200 kg/ha can be obtained but viability of seed is just one year.