Onion varieties differ in sweetness, size and shape. Other than some hybrids, they generally grow in 90 days.
The most common varieties is yellow onions. Yellow onions have a golden skin and off-white to yellowish flesh inside. This varieties grows in most climates, but it is ideal for a warmer places since it does not store well. Traditional yellow varieties are the flat-shaped granex and the rounder grano types. Because of it's sweetish taste, yellow onions are most commonly use in salads and sandwiches.
The Red onions have dark red to purple skin and flesh that is red and white on the inside. They are very crisp and pungent with a spicy flavor. This s a type popular with both farmers and buyers alike because of its long storage life.
There are also white onions. As the name implies, this variety is white on the inside and outside. It weighs around 1 lb each, with a thin skin and a very mild taste.
|Serving size: One medium-size onion (150 grams about 5.3 ounces)|
|Calories from Fat||0|
|% Daily Value *|
|Fat 0 g|
|Carbohydrates 14 g||5%|
|Protein 1 g||2%|
|Cholesterol 0 mg|
|Sodium 10 mg|
|* The Percent Daily Values are based on a 2,000 calorie diet, so your values may change depending on your calorie needs. The values here may not be 100% accurate because the recipes have not been professionally evaluated nor have they been evaluated by the U.S. FDA.|
For optimum development, onions require cooler weather during the early stages of growth and a dry atmosphere with high temperature as they mature. Planting is normally done as early as October for yellow onions and as late as January for the red variety.
Onions can be grown on any fertile, well-drained, non-crusting loam with high moisture capacity. The ideal soil pH ranges from 6.0 to 6.8. Anything below this hinders growth because of trace element deficiencies or, at times, aluminum or manganese toxicity. Onions can also be grown on alkaline soils. Although ideal temperature for early development is between 13 and 14 degrees Celsius, the range for seedling growth can be between 20 to 25 degrees Celsius.
Before planting, soils should be plowed to eliminate debris and soil clods. Onions are generally tolerate crowding because their root growth is not aggressive,. This is truer in friable (easily crumbled) soils such as peat and muck. however, you might want to watch out for competition from aggressive systems, such as weeds, as this can potentially affect onion growth.
Direct seeding method:
- Direct seeding is the preferable method of planting onions. Results are very good when the seeding is done early enough in the season to allow sufficient early growth before bulbs start to form. The final yield depends on the number of leaves that are formed prior to bulbing.
- Show the seeds 6-18 mm deep into the soil, deeper if the soil is muck.
- For a normal-size onions, plant the seeds 7.5 cm apart. To get small onions for pickling or pearl onions, spacing can be at 2.5 cm. Spacing of 10 cm or more between planting rows will yield large bulbs.
- A 300 to 500 sq. m. of seedbed can be produce enough transplants for hectare.
- Prepare beds that are a meter wide and integrate animal manure and rice hull into the soil.
- Place seeds in row across the bed around 7 to 10 cm apart, spreading them thinly and evenly.
- Cover the seeds with compost and mulch with rice straw or grass clippings.
- Maintain adequate soil moisture through every step of this process.
- Use nylon netting or removable plastic tunnels to protect the seedbed from direct sunlight and rain
- A week before transplanting, reduce watering and expose the seedlings to direct sunlight.
Transplanting the Seedlings
One month before transplanting, spread 10-15t/hectare organic manure and incorporate into the soil through plowing and harrowing. Seedling are usually transplanted 4 to 6 weeks after sowing. Transplant should have three to five well-formed leaves at transplant time. Carefully uproot the seedlings to prevent any root damage; then plant them in rows 15 cm apart and 3 to 5 cm between transplants.
Use a string to mark the proper spacing between transplants. With a dibble or long stick, make holes in the ground deep enough so that the white portion of the plant is below the soil surface. Press the soil firmly around the base of the transplant and water immediately after.
Application for Fertilizers
Onion plants use up a lot of nutrients from the soil. Aside from the organic manure applied before planting, one or two side dressings of nitrogen may be applied via the irrigation system throughout one growing season.
If you are unsure of the requirements of your soil, a one-hectare field requires 8.5 to 11.4 bags of ammonium sulfate (21-0-0), 6.6 to 26.7 bags of super phosphate (0-18-0) and 2 to 4 bags muriate of potash (0-0-60). Method of application:
- Apply all of the phosphate as basal fertilizer.
- Apply half of the ammonium sulfate and half of the muriate of potash as basal fertilizer.
- Side-dress the remaining ammonium sulfate and potash at 30, 45 and 60 days after transplanting.
Bulb onions need enough moisture to grow continuously and steadily. They are commonly watered via furrow irrigation, usually ranging between four to seven days. Overhead systems or subsurface seep irrigation are used for light sandy soils. At the bulbing stage, onions need a lot of water. this need drastically drops as it grows, and excessive moisture must be avoided during the growing season. two to three weeks before harvesting, stop irrigation altogether.
Controlling Pests and Diseases
Most common among pests that attack onion plants are those that cut through the outer layer of onion leaves and stems stuck the plant sap. Infestation is more common during the dry season when entire fields may destroyed. An effective way to combat this is to spray Diazinon every 7 to 10 days or about 6 applications. Young plants can be treated with Mancozeb weekly up until bulbs starts forming. Traditional methods of control for general health of your crop include long rotations with unrelated crops, maintaining good soil drainage, and proper field maintenance.
Purple blotch (Alternaria porri); leaf blight (Botrytis spp); white-tip disease (Phytophthora porri); downy mildew (Peronospora destructor)
Follow correct irrigation procedures. Clean debris from previous crop. Diseases of the leaves can be controlled by spraying compost tea (liquid secreted by fermenting rice compost for 10-14 days). Remove infected leaves. Practice crop rotation. Spray Mancozeb at 7-day intervals.
Pink root (Pyrenochaeta terrestris)
Expose the field to sunlight.
Bacterial soft rot (Erwinia carotovora); neck rot (botrytis allii); onion smut (Uroccystis cepulae)
These storage diseases can be controlled by ensuring good air circulation during curing, packing and storage. harvest only mature bulbs.
Sour skin (Pseudomonas cepacia); slippery skin (P.alliicola)
Control moisture by using furrow irrigation. Include copper sulfate in the final irrigation before harvest. Apply fungicide.
Thrips (Thrips tabaci)
Use overhead irrigation or high pressure water spray with hot pepper extract or insecticidal soap solution. Remove infectal leaves. Spray Diazinon at 7-to 10-day intervals.
Army worm (Spodoptera exigua); cutworm (Argotis spp.)
remove infected leaves. Spread wood ash over the plants.
Leaf miner (Liriomyza spp.)
Remove infected leaves. Spray plants with disinfecting solution composed of one part commercial bleach to 10 parts of water. Rinse after one hour.