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Chilli / Red Onion / Big Onion


Big Onion

Recommended Varieties

pusa_red Rampur
Pusa red Rampure
pusa_red Nasik_re
Kalpitiya selection Nasic red

Following varieties are recommended for Sri Lankan conditions considering factors such as high yield, seed setting ability, storage adaptability, pungency and colour etc.


Pusa red

Variety was developed at IARI, New Delhi, India. It is well adapted to dry zone of Sri Lanka. 90- 100 days to mature the crop. Average yield is about 20- 25 mt/ha. High pungency, Light rose in colour

 

Rampure
Originated from India. Well adapted to dry zone in Sri Lanka . Takes 85- 90 days to mature the crop. The yield is about 15-20 mt/ha with better storability. light rose in colour, High pungency


Agri found light red

Variety developed at India by mass selection well adapted to dry zone to cultivate as a yala cropn under irrigation. Pink in colour and it takes about 90-100 days to mature. average yield is about 15-20 mt/ha with good storability.


Kalpitiya selection

Bulb colour is slightly rose medium pungency. 85-90 days takes for maturity, Light rose colour, Medium pungency


N53
It takes 90-100 days for maturity and the colour of bulbs dark red. High pungency.

Nasic red

mainly cultivate as vegetable. Dark red in colour poor storability.
To cultivate one ha of land it is required 7.5 - 8.5 kg of true seeds. If use proper nursery techniques with high quality seeds it can be reduced up to 6-7 kg/ha.

Nursery Management

Requirement for a nursery site

* Availability of direct sunlight 
* Well drained loamy soil
* Fallowed field for few seasons
* Sequential cultivation of onion for several seasons will results to increase soil pathogens

Land Preparation

* Plough or turn the soil to 20 to 25 cm depth, 3-4 weeks before seeding 
* Make a good tilth turning soil several times
* Allow the soil to expose to direct sunlight during land preparation

Seed bed preparation

* Standard bed ( 3m x 1 m x 15 cm) 
* Surface soil of a bed should be in fine tilth
* In-corporate decomposed organic manure into 10 cm depth ( 10 -15 kg/ std bed) before sterilization of the bed

Sterilization

To destroy the causal agents (Pythium, Phytopthora, Rhizoctonia, Sclerotium, Fusarium spp )of damping off. Sterilization is essential using any of the recommended method as mention below.

 

Turning the soil once a week and expose to direct sun light about 3 times
Burning ( using rice straw and rice husk)
Well prepared nursery beds
Fungicide treatment
Apply the fungicide as mentioned below
Fungicide
Amount/std bed

Captan 50% or 80%WP 
20 g/16 litre of water
Thiram 80 % WP 25 g/16 litre of water
Thiophanate methyl 70 % WP 10 g/16 litre of water
Thiophanate methyl 50%+ Thiram 30%
18 g/16 litre of water


Fertilizer application
In -corporate the following mixture to the surface of the bed

Urea                            15g
Tripple super phosphate     30 g
Mureate of Potash            15g

Seed Treatment
To control the spread of disease through seed add 4-6 g from the one of above fungicides to 1 kg of seeds and mix thoroughly

Sowing
a) Apply seeds at the rate of 40-50 g/bed to the depth of 1 cm in rows and 10 -15 cm apart. Cover with straw mulch after seeding.
b) Daily apply water after covering and until germination

Germination

a) Usually completed in 8 - 10 days
b) Remove mulch after germination
Cover the beds using white poly- ethylene to protect from rains and sun light during initial stage of seedlings

Hardening

Increase the exposure time and watering interval should be increased.

Suitable seedlings
The seedlings, which have 3-4 leaves, 15-18 cm height, slightly bulbs is marked and with the age of about 35-40 days are better to transplant.
It is very essential to select the seedlings prior to planting to achieve good bulb yield

Field Establishment

Soil condition

Onion crop can be successfully produced on most fertile soils. soil pH in the range 6-7 is usually recommended . But on organic soils a lower pH is satisfactory. Suitable soil types ( Reddish Brown Earth and Regosols ) are available in the dry zone of sri lanka


Climate

Crop need longer day length ( > 12 hours) because it is a long day plant. However, some varieties which can be cultivated in the tropics are need 11-12 hours day length period. Only this type of varieties can produce good bulbs under Sri Lankan condition during yala season.
There should be lower rain fall ( less than 750 mm ) through out the cropping period. At the harvesting period ( last 1 month) need to be dry and hot for better crop.
Less than 70 % RH is favorable.


Time of planting

It is very important to decide the proper time of nursery application because it decides the time of planting. In Sri Lanka it is recommended from early April to early May for nursery application. The climatic requirement of the crop is in the country prevailed during Yala season (May to September). Therefore, it is essential to transplant by mid May - mid June to achieve good yields.
Crop establishment using dry sets is practiced during late Maha (December to February)
However, climatic conditions are not favorable to the crop during this period. Therefore, set planting is not much popular.


Land preparation

Well-drained land selection is essential. Cropping site is very critical factor to decide the yield. Primary weed control is needed prior to land preparation. This can be done by manually or using none selective weed killer
eg. Glyposate( 2-4 liter/ha) apply when weeds are actively growing and 10-14 day before land preparation
Plough the land at the depth of 8 inch and prepare the soil smoothly
According to the irrigation facility better to decide the bed width and length. Normally recommend (1m x 3 m x 15cm beds) Prior to planting it is essential to apply any kind of well-decomposed organic manure at least at the rate of 10 mt/ha.


Transpalnting

Fertilizer N,P and K should be incorporated into the soil 2-3 days before planting. For better yield 100-156 plants/m2 is preferable. One cm depth of planting is encourage better bulbing. Deep planting is not suitable for good bulb development. Selected and pre treated seedlings must be used for planting


Seedling treatment

Thiophanate methyl 70% WP 20g/10 lit of water
Thiophanate methyl 50% + Thiram WP 18g/10 lit WP 20g/10 lit of water
Thiram 80 % WP 150g/10 lit of water

Dip seedlings for 20-30 min. prior to planting

Crop Management

Weed control

Applying of pre emergence weedicide after planting and followed one or two hand weeding effectively control the weeds of the crop.

Alachlor - 480g/l EC- 3-5lit/ha
Oxyfluorfen - 240 g/l EC - 0.5 lit/ha

Fertilizer incorporation

P and K are normally incorporated into the soil prior to planting. In most instances the majority of the N is also incorporated at this stage, but additional nitrogen is also applied during crop growth.

Fertilizer recommendation

Time Kg/ha
N Urea P2O5 TSP K2O
MOP
Basal fertilizer (2 days before planting)                
30 65 45
100 30
50
First top dressing ( 3 week after planting) 30 65 - -
-
Second top dressing ( 6 week after planting)
30
65
- 15
25

TSP- Tripple Super Phosphate MOP-Mutreate Of Potash

Water management

At the initial stages of the crop water requirement is high. Therefore, it is necessary to irrigate about 3-day intervals and later it can be increased. This intervals may be depend on the soil type. However, after irrigation drainage improving is very essential unless the crop may fail due to ill drainage condition. Two weeks before harvesting water supply should be stopped to increase the quality of the harvest.

Technology for Pest and disease control

Thrips ( Thrips tabaci)
Most damaging pest in Sri Lanka. Warmer and windy climate at July, Augustpromote to increase the pest population . Rasp and pierce the leaf cells and sap release. Insect active when at the poor sunlight in the morning and evening.
Control 
Establish the crop at proper time
Proper land preparation
Weed control
Chemical control:
Thiochlorid 400 ml/ha
Diasinon 50% EC 1400- 2100 ml/ha
Imidochlorprid 500ml/ha
Fipronil 500 ml/ha
Tokuthiopn 1000ml/ha
Carbaryl 0.35 kg/h

Leaf eating caterpillar (Spodoptera exigua)

Control
Destroy crop residuals
Proper land preparation
Manually destroy the eggs and larva
Chemical control:
Carbofuran 3% 15-20 kg/ha
Diasinon 50% EC 1400- 2100 ml/ha
Deltamethrin 25% EC 270 ml/ha

Root eating ants ( Dorylus spp)

Chlorpyrifos 200g/l EC 40ml/100m2
Chlorpyrifos 400g/l EC 20ml/100 m2
Diazinon 500g/l EC 115 ml/100 m2

Disease

Purple blotch ( Alternaria porri)
Initially irregular white spots can be seen on leaves. Later become large and brown, oval shaped spots with pink colour margins. Finally become black patches.
Control
Remove and destroy crop residuals
Land preparation with good tilth
Chemical control 
Mancozeb 80% WP 0.9-1.3 kg/ha
Chlorothalonil 500 g/ l SC 1.4-2 l/ha
Maneb 880% WP 0.9-1.3 kg/ha

Anthracnose ( Colletotrichum gleospordes)
Initially oval shape whitish sunken patches can be seen. Later conidia can be seen on this patches Twisted leaves become yellow. Finally bulbs rot may happen

Control
Infected lands are not suitable for onion cultivation
Remove infected parts from the field
Improve the drainage
Crop rotation ( 3-4 season - legume cultivation)
Seedling treatment

Chemical control
Mancozeb 80% WP 0.9-1.3 kg/ha
Thiophanate methyl 70 % WP 0.3- 0.5 kg/ha

Thiabendazole 45% DF 0.9- 1.3kg/h

 

Downy mildew ( Peronospora destructor)
Irregular white spots on leaves. Yellowing and drying from the tip of the leaves

Control
Remove and destroy crop residuals
Land preparation with good tilth
Chemical control Mancozeb 80% WP 0.9- 1.3 kg/ha
Captan 80 % WP 0.6-0.8 kg/ha

 

Bulb rot

(Fungi : Fusarium spp, Phythium spp, Sclerotium spp, Rhizoctonia spp)
Yellowing , Tip drying, root rot and initiate secondary roots, soft rot of bulb and neck rot could be seen

 

Control

Destroy crop residuals

Improve drainage
Should not irrigate through infected areas
Seed treatments ( Captan 6g/1kg of seeds, Thiram 4-5 g/1kg seeds, Homai 4g/ 1 kg seeds)

Soil treatments
Thiobendasole- 5g/ 10 m2
Thiram 70 g/ m2
Bacteria: Pseudomonas spp
Control Destroy crop residuals, Remove infected plant from the field, Proper water management
( irrigation and drainage), and crop rotation

 

True Seed Production

Technology for true seed production
True seed production during maha season

* Select medium size uniform ( 60-70 g/bulb) mother bulbs from recommended variety with related characters and store up to December. Vernalized ( store bulbs under 8-15 c0 for two weeks just before planting ) bulbs treat well from the recommended fungicide . Apply basal chemical fertilizer 2 days before planting ( TSP- 100kg/ha, MOP- 50 kg/ha 1st top dressing at one week after planting ( Urea- 65kg/ha) 2nd top dressing at flower bud initiation ( Urea -65,kg/ha MOP - 25kg/ha). Plant mother bulbs on raised beds with the spacing of 22.5 x 22.5 cm. Suitable time of planting is early January and the crop should be covered with white polythene at the height of about 3ft. at the rains and night. Better to cultivate crops like sunhemp around the crop to attract the insect to increase the pollination. Mature seed can harvest about 3 months after planting. Seed must be well dried unless germination may be loss quickly.
* Pest and disease control
Bulb rot, purple blotch and anthracnose are the major diseases in maha season due to unfavorable weather during period. Control of diseases are similar as in the crop. Chemical application at flowering must be done carefully , because the insects attraction may be restrict.

 

Identified suitable areas for true seed production during maha season
Because of the higher disease incidences it was needed to find favorable areas for true seed production. In Bandarawela (IM3) area it has given higher seed yield compared to DL1 areas with low disease incidences. Planting time and cultural practices are similar to DI1 region. However it takes longer period ( more than 30 days compared to DL1) for crop maturity.

 

True seed production under poly tunnels during maha season
Rainy weather condition during December to April cause to fail the seed crop due to high disease incidences. Therefore, it recommend true seed production under poly tunnels in which side opening are allowed to ventilation . All the agronomic practices are similar to maha season true seed production. Higher true seed yield can be obtained from the poly tunnels compared to normal crop with low disease incidences.


True seed production during Yala season

Medium size ( 60-70g/bulb ) mother bulbs which are produced in previous Yala season need to be stored up to May. These mother bulbs need to plant at early May to mid May with the spacing of 15 x 15 cm on raised beds. Bulb treatment, fertilizer and cultural practices are similar to maha crop and not necessary to cover the crop . Disease incidences are very low compared to maha season and higher seed yield could be obtained compared to maha season.

Harvesting & Post-harvest Technology

Field curing and harvesting

The crop matures about 100 days from transplanting. It is depending on the cultivar and the weather condition. At the 50 % neck fold stage other plant must be bent or press using plank. Thereafter water supply must be stopped. After 14 days crop can uproot and need to shade dry to improve the quality and storability. Then bulb can be seen covered with dry scales. Later, the harvest suitable for storage.


Storage of onion

* Suitable varieties for storage Agrifound Light Red, Pusa Red, Kalpitiya selection, and Pampure
* Application of 75- 150 kg N/ha is adequate to obtain good quality bulbs for storage. Application of over doses
drastically reduce the storage
* Malic hydracide sprayed at 50% leaf fall stage reduced the sprouting losses especially when when stored at low
temperature and Carbendazim sprayed to the crop ( 8g/10 l ) two weeks before harvesting decreased rotting
losses in storage
* Bulbs could be stored up to 10 cm thickness without affecting the storability . Due to high high relative humidity
during the storage period ( maha) prevents any futher increase in pile thickness
*  Midium size ( 50-60 g) bulbs are the most suitable bulbs for storage

*  Environments with low RH ( <80%) and moderate temperature ( 20-300C ) are suitable for big onion storage

 

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