Onion Variety – Jambar F1
Onion is a key Vegetable crop in the region, Onions are consumed than any other vegetable making it very marketable and profitable. In E.A Onions are successfully grown on both large and small scale farms. As with any crop, proper management of the crop from seedling to harvest is essential for farming success. We share some of these crop management tips with you.
Try them out as you grow our short-day red Onion
Onions can be grown in a wide range of climatic conditions; they are quite hardy and can tolerate temperatures as low as -6⁰c. However, good bulb formation requires temperatures from 15.5⁰c with an optimum temperature of 21- 27⁰c, coupled with the correct day – length. Short day Onions such as Jambar F1 have 11.5 – 12.5 hours day length threshold for bulb formation.
• Onions do best in best in well drained soils that are at least 650mm deep, shallow soil may be utilised, but with adoptions in management practices.
• Ensuring a PH range of 6.02 – 6.8. Lower PH levels can result in problems with regard to micronutrient uptake.
Though onions can be produced on a wider range of soil types, avoid heavy soils as this may lead to problems such as bad aeration, crusting and a blemished products of lower quality.
• On well-drained soil, prepare a fine and even seedbed.
• It is advisable to use seedling trays to ensure that little or no seed is lost during this process.
• Commercial plant raisers can help farmers raise healthy seedlings for use.
Fertilizer application s should be determined by soil analysis. Most onion roots are in a 15cm radius from the stem and are therefore shallow feeders. If the soil pH is less than 6 or the available calcium is less than 2300kg per hectare, apply ad incorporate agricultural lime at the rate of 2500kg per hectare about 8-12 weeks prior to planting.
Lime requires time to react with acid soil to raise the Ph.
In soils low in phosphorous apply and incorporate approximately 94kg of phosphate per hectare. Generally, it is suggested that the phosphate be banded 6- 8.5cm below and on both sides of the rows where onions will be planted.
Nitrogen applications are critical in terms of quantity and timing of application. The amount of nitrogen supplied depends on the soil analysis. Poor soils may require up to 180kgs / hectare for direct sown crops. Average soils would need lower levels – 120 – 140kg/ hectare.
Soils low in Potassium require an application of 100kg/ hectare before planting. The remaining potassium can be applied with the first nitrogen application at a rate of 85kg/ hectare, (three weeks after transplanting or when seedling has reached 3- leaf stage)
In applying pre- plant fertilizers it is best to band 6to 8 cm below the seed or transplant, rather than broadcasting and incorporating.
Seedling are usually ready 5 to 6 weeks after seedling, when a majority of the seedlings necks are pencil – size (65 -80 mm) in diameter, 10-15 cm tall.
If irrigating, ensure systems ready, so that irrigation can commence immediately after transplanting to prevent losses of the plant population.
Plant spacing: 15-20 cm between rows x 8 cm within rows.
When planting under irrigation
Irrigate soil to field capacity before planting in order to build up moisture reserves for later use by the crop.
Irrigate 3-5mm daily after transplanting so as to keep the soil cool and moist.
Direct seeded onions growing under hot dry conditions may require two irrigation cycles per day.
Water shortage at any stage during growth may result in decreasing yields. Adequate watering promotes good growth and helps keep the soil firm around the onions.
Do not over-irrigate as onion bulbs that are over-watered tend to be soft with a poor shelf life.
Onions develop slower than other vegetable crops and are more susceptible to weed competition especially during the early growth stages, this can result in yield losses.
Weeds can be controlled successfully through either pre- or Post emergence herbicides, use only registered products.
Care should be taken to avoid damage to the bulbs when mechanical weed control measures are used.
Pest and disease Control
Trips are the major pest in onions, if not controlled they can cause reduction in quality and quantity of produce. A number of diseases do attack onions but the major ones include; Downey mildew and purple blotch. Most diseases that occur in onions can be controlled through management practices, by growing resistant cultivars and chemical sprays.
Harvesting and Handling of Onions
Harvest when about 50 percent of the plants have lodged;
Lodging of plants indicates maturity of the bulbs. The onions are lifted mechanically or by hand and in windows for drying on the land.
Cure at temperatures of at least 24⁰c for 7 days or expose for 12 hrs to 30 – 40⁰c.force air curing at RH75- 80%.
Dry hot weather is beneficial for drying of bulbs at the harvest stage.
Relative humidity during drying plays an important role in determining the quality and colour of the scale leaves.
Trim off Necks and roots after they have dried completely, then transport to packing sheds.
Sweet Onions are stored at 0⁰c, for 3-4 weeks, while pungent onions can store at 0⁰c, for 6 -9 months, at RH 65-70%, with good air circulation.
Onions should be handled with care to prevent bruising and cracking which leads to weight loss due to moisture loss, or infection by pathogens.
Jambar F1 yields up to 23 tonnes per acre.