An onion (Allium cepa L.), also known as the bulb onion or common onion – is a popular vegetable of considerable economic importance. The onion’s shape, size, and color are varietal characteristics.
The success of growing onions depends on a number of factors, and one of the most important is the selection of the right variety, in accordance with specific climate and soil conditions. Other factors to consider are the timing of planting, the method of cultivation and the use to which the crop is intended.
Three methods of growing onions are used: from seeds, from seedlings, from onion sets.
GROWN FROM SEEDLING
The advantage of this method is the possibility of obtaining a high yield of large onions, with a diameter of more than 6 cm, even in size and shape. It allows also to accelerate the harvest by 3–4 weeks, compared to cultivation by sowing. Seedlings are produced in heated facilities – greenhouse, polytunnel or in a cold frame. A few days after sowing, it is very beneficial to use the microbial product BACTIM® RADINET for better development of the plant root system. During the production period – it is recommended to fertilize the seedlings with a solution of PLONVIT® OPTY multi-nutrient fertilizer. The seedling production period lasts 6–8 weeks. A well-grown seedling should have 2–3 leaves with a length of about 12 cm. In Polish climatic conditions – it is planted in the field in the second half of April to early May. Preparation of the field is similar to cultivation by sowing.
Onion is a vegetable with high climate and soil requirements. The best soils for cultivation of this species are fertile and humus, non-crusting, early suitable for use, well retaining moisture, but not waterlogged. The optimum soil reaction (pH) for onions grown on mineral soils is 6.5–7, and on peat soils it is 5.8–6.5.
The shallow root system of onions means that, even short-term nutrient deficiency may have a negative impact on plant growth and yield. Therefore, it is necessary comprehensive assessment of the requirements of the plants at any stage of their development. This will allow them to be properly fed and biostimulated.
Apart from basic soil fertilization, foliar fertilization is a standard. Its main advantage is the quick and effective supply of the most-required nutrients to plants at particular stages of development.
- Phosphorus, delivered by foliar application, after adaptation of seedling, has a beneficial effect on the rate of development and growth of the assimilative leaves. It also supports the development of the root system (GROWON® or PLONVIT® FOSTAR or PLONVIT® PHOSPHO).
- During intensive growth of assimilative leaves, it is especially important to have an optimal supply of nitrogen (PLONVIT® NITROMAG or PLONVIT® NITRO). Well-formed assimilative leaves are a strong guarantee of a high onion yield.
- From the beginning of the formation of the onion bulb, very important is potassium, which is responsible for production and transport of photosynthetic substances to the harvestable plant parts. Also, it regulates water management of plants and sugar biosynthesis (PLONVIT® KALPRIM, PLONVIT® KALI).
- In the fertilization of onions, magnesium should be taken into account (MIKROKOMPLEX®), as well as sulfur (PLONVIT® SULVIT), especially when a nitrate-urea solution is used to fertilize the plants with nitrogen.
- The most important of the micronutrients are: zinc (AMINO ULTRA® Zn-24 or MIKROCHELAT Zn-15) and manganese (AMINO ULTRA® Mn-22 or MIKROCHELAT Mn-13), as well as copper (AMINO ULTRA® Cu 24 or MIKROCHELAT Cu-15) and molybdenum (MIKROVIT® MOLYBDENUM).
- For ensure large yield quantity and good quality – biostimulation is very important. The foliar applications of TYTANIT®, OPTYSIL®, AMINOPRIM®, VANADOO®, PLANTICINE® may stimulate plants for better growth and yield and for improvement of tolerance to abiotic (weather conditions) and biotic (disease and pest appearance) stresses, as well as the capability of accelerating the recovery of plants after the occurrence of stressful conditions.
- Particularly noteworthy are the highly alkaline line of fertilizers ALKALIN: ALKALIN™ K+Si, ALKALIN™ KB+Si, ALKALIN™ PK 10:20. Alkaline pH of fertilizer solutions activates the immune factors of plants.
- It is important to reduce nematodes in onion crops. For this purpose, the use of BACTIM® RECEPTOR is recommended. It is a bioproduct especially advisable for sites threatened by nematodes. This product can be used prophylactically as a single dose or several times depending on the pressure of nematodes. On nematode-free sites, it is worth using BACTIM® VIGOR. This product positively affects the size and quality of the crop. It reduces the susceptibility of plants to abiotic and biotic stresses.
INTERMAG’s wide range of products, allows you to develop your own individual foliar fertilization and biostimulation program, considering local soil conditions, crop intensity, stage of plant development and availability of various products.
