Production Technology of Onion in Bangladesh

Production Technology of Onion in Bangladesh

Land and soil

Onion may be grown on various soils. But it grows well in friable and well-drained

sandy-loam to clay-loam soil along with optimum PH range between 5.8 and 6.5. The

crop is sensitive to high acidity, alkalinity and salinity. Onions do not thrive well in

the soil below PH 5.8 because of trace element deficiencies and sometimes

aluminum/manganese toxicity. The water-holding capacity of the soil should be high

as onion is a shallow rooted crop. Good drainage is essential. Waterlogging may

cause failure of the crop. Sandy soil needs more and frequent irrigations but favour

early maturity, whereas heavy soil gives rise to misshapen bulbs.

Seed rate

Seed rate of onion depends on its quality, planting system, planting time, spacing etc.

4-5 kg seeds for transplanting system whereas 7-8 kg true seeds and 1200-1500 kg

onion sets are required for cultivation of one hectare land in direct seeding and set

planting method, respectively.

It is also a summer season corp. Bulbs is round in shape

and red in colour. Plant height: 30-40 and 55-65 cm

during early and late kharif season, respectively. Weight

of bulb: 18-22 and 50-55g in early and late kharif

season. The bulb is moderately pungent. The shelf life of

bulbs depends on prevailing rains. However, the bulbs

can be stored maximum two months. Seed yield: 400-

500 kg/ha. Bulb yield: 10-12 t/ha for kharif-1 and 17-20

t/ha for kharif -11. Duration: 90-105 days (kharif-1) and

130-140 days (kharif-11).

BARI Piaz-3

(2000)

It is a high yielding variety grown for rabi season.

Plant height: 50-60 cm, 10-12 leaves in each plant,

globular and pitcher-shaped bulb, 60-75g per bulb and

dark red in colour. The bulb is pungent in taste.

Comparatively less infestation of pest and diseases.

Bulb yield: 17-22 t/ha. Duration: 160-170 days.

BARI Piaz-4

(2008)

This variety is mainly grown in kharif season but it

may also be grown throughout the year. Suitable for

early and late kharif cultivation. Short duration. Plant

height: 35-45 and 65-75 cm in plant height for early

and late kharif season, respectively. Globular shape

bulb, 30-40g and 70-80g per bulb in early and late

kharif season and dark red in colour. The bulb is

moderately pungent in taste. Bulb yield: 12-16 t/ha

(kharif-1) and 18-20 t/ha (kharif-11). Duration: 60-80

days (kharif-1) and 115-125 days (kharif-11).

BARI Piaz-5

(2008)

Name of

Varieties Important Characteristics Crop

(Year of Release)

Seed treatment

Seed should be treated with Dithane M-45 @ 2 g/kg of seeds to avoid damage from

diseases before sowing and protect seedlings from damping off (Pythium spp).

Time of sowing

In transplanting and direct seeding method, the best time for sowing rabi (winter)

crop is late October to November. In case of early and late kharif (summer) onion, it

is sown in February to March and July to August, respectively. In set planting

method, the optimum time is September to October. In case of seed production, late

October to November is the optimum time to plant seed bulb.

Sowing method

Direct seeding: In this method, seed rate is high. Intercultural operation is difficult for

improper plant population. The plants can not use natural resources properly. The bulb

yield is poor. Shelf life of the bulbs is comparatively very poor but labour cost is low.

Onion sets planting: The bulbs produced in this method are entirely fresh (green

onion) and these bulbs are immediately consumed. Premature bolting occurs in this

crop planting. Seed rate of the sets are high.

Seedlings transplanting: This is conventional seedling transplanting method, widely

practiced by farmers. This method shows better results for longer shelf life of onion

bulbs although the labour involvement and cost is high. The seedlings are usually

transplanted on flat beds at a spacing of 15 cm from line to line and 8-10 cm from

plant to plant.

Seedbed preparation

Onion seeds are sown in nursery beds to raise seedlings. The raised beds of 3 m long x

1 m wide and 20-30 cm high are preferred. The length of seed bed may also be formed

in a convenient length depending upon type of soil, level of land, irrigation method

etc. Raised bed is necessary to avoid problem of waterlogging in heavy soil. About 50

cm distance should be provided between 2 beds for easy operation of watering,

weeding, spraying of pesticides etc. The surface of the beds should be smooth and

well-levelled. Insecticide like Furadan should be incorporated in the seed bed to kill

the soil insect-pests. The bed may be covered with polythene for solarization.

Land preparation

Prior to planting sets or direct seeding or transplanting seedlings, land is to be

ploughed sufficiently to eliminate debris and soil clods. The onion land should be

ploughed to a fine tilth by 4-5 times with a sufficient interval between two ploughings.

The land may be ploughed by tractor or power tiller or country plough. But for well

pulverization of the field, ploughing by tractor-driven implements is suitable. After

ploughing, laddering is done for proper leveling. The field is then divided into beds of

1 m wide along with convenient length and channels of 50 cm wide.

Fertilizer dose and application methods

The requirement of nutrients depends on soil type, topography, AEZs, varieties, soil

nutrient status etc. Onion responds very well to organic manures. About 5-10 tons of

cowdung per hectare is adequate. Onion requires higher levels of fertilizers for

maximum yields than most other vegetable crops. Green manuring with Dhaincha

(Sesbania aculeata) and Sunnhemp (Crotalaria juncea) may be done to enrich soil

health. Fertilizer dose and application methods are furnished below:

Manures and fertilizer Total amount At the time of 1st installment 2nd installment

/ha last ploughing

Well decomposed Cowdung 5.0-10.0 ton All - -

Urea 240 Kg 80 80 80

TSP 220 Kg All - -

MP 150 Kg 75 38 37

Gypsum 110 Kg All - -

For seed production

Manures and fertilizers are to be applied in land with well decomposed cowdung: 10

tons, urea: 260, TSP: 300MP: 150, Gypsum:100 and Boric acid:10 kg/ha,

respectively. The entire quantities of well-decomposed cowdung are to be applied just

after opening of the land. The total amounts of phosphorus, Gypsum, Boric acid and

two-third of Potassium should be added during final land preparation. The entire urea

is to be incorporated in three equal splits 20, 40 and 60 days after seed bulb planting.

The rest amount of Potassium should be applied 60 days after seed bulb planting.

Irrigation

Onion is a shallow rooted crop. Its root system is normally restricted to top 3 cm and

roots penetrate seldom deeper (15 cm). The water requirement in onion crops depend

upon crop growth, soil type, planting season etc. The water requirement at initial

growth stage is less. At bulb formation, irrigation is necessary and moisture stress at

this stage may lower the yield. The field should not be kept dry for long spell which

otherwise results in splitting and allow to crop early maturity resulting lower yield.

Frequent and light irrigation at weekly intervals have shown good results in bulb

development, increase in yield and quality of the produces. Depending upon rain and

soil type, 5-6 irrigations are enough. As the onion begins to mature and the tops begin

to fall down, irrigation has to be terminated to stop root growth and allow the outer

scale of the bulb to become dry and firm. Thus, irrigation should be stopped at least

15-20 days before harvesting for improving the keeping quality of bulbs.

1.3 Intercultural Operation

Cultural operation keeps the field absolutely free from weeds to produce a good crop

of onion. Onions are one of the vegetable/spice crops most prone to weed infestation.

The crops are poor competitors against weeds due to its slow establishment and a

canopy of short upright leaves. Henceforth, weeding is the most important activity for

this crop.

Special operation for seed production

Earthing up

Soils around the plants should be done to protect seed crops from fall down.

Staking

Staking is one of the most important activities for intercultural operation in onion

seed crop. Without this activity the program of onion seed production may be failed

due to breaking of flower stalks by strong wind. Staking should be provided around

the unit plots at 65 days after planting of seed bulbs with bamboo sticks and jute cord

to keep the flower stalk erect and to protect them from strong wind. Breaking the

flower stalks leads to produce higher percentage of chaffy seeds resulting in lower

quality and low yield of onion seed.