1, soil: onion is suitable for pH6.5-7.5 loam cultivation, nursery ground requires fertilizer live loose, adequate bottom moisture, the seedling period to prevent the topsoil from sloughing, seedlings began to grow rapidly when fertilizer, planting 10-15 days before the control of soil moisture, to prevent futile collapse.
2, fertilizer: onions like fertilizer, and requires a balanced application of nitrogen, phosphorus, potassium. In the pre-growth of nitrogen fertilizer requirements more, the late need for more phosphorus, potassium fertilizer. Pay special attention to the application of phosphorus fertilizer, because the lack of phosphorus fertilizer will lead to poor plant growth, yield decline. At the same time, we should pay attention to the content of sulfur elements in onion land, soil sulfur deficiency will affect the effect of yield increase.
3, temperature: Onion is resistant to both cold and heat. Although the temperature in general does not have much effect on the growth of onions, but the appropriate temperature conditions are conducive to high quality and high yield.
4, moisture: Onion root hairs less, absorb water and fertilizer capacity is poor. Most of the root system is distributed in the soil surface layer, like wet, require high soil humidity, but the root system is afraid of flooding, high temperature and high humidity is very easy to cause root death.
5, light: onion light intensity requirements moderate. Because the onion's tube-shaped leaves in the conditions of dense planting, can still get good light conditions, so do not need strong light. Strong light has an adverse effect on the growth of onion, which will cause the aging of the leaf body, fiber increase, quality decline, and even loss of food value.
Morphological Characteristics:
Root: The root is white, stringy, with few and short lateral roots. The number, length and thickness of the root grows with the increase in the total number of leaves occurring in the plant. Onion hair growth peak period, the number of roots up to more than 100.
Stem: The stem is extremely shortened to a globular or compressed globular, solitary or clustered, 1~2cm thick, with a white, membranous outer skin that is not ruptured. The upper part bears multi-layered tubular leaf sheaths, and the lower part is densely covered with fibrous roots. When the growth point of the seedling end differentiates into flower buds, it will gradually develop in addition to the flower stem. Onion flower stem is stout, hollow and unbranched, 30~50cm long.
Leaves: Leaves consist of leaf body and leaf sheath, leaf body is long conical, hollow, green or dark green. The single leaf sheath is cylindrical. The multi-layered set of leaf sheaths and the 4-6 young unsheathed leaves wrapped within them form a clavate pseudostem.
Flowers: attached to the tip of the flowering stem, before flowering, the developing umbel is hidden in the involucre. Nutritional organs of the full-grown onion plant, an inflorescence has 400-500 flowers, more up to 800 or more. The flowers are bisexual and cross-pollinated. Each flower has 6 pieces of perianth and 6 stamens. When the pistil is mature, the style is 1 cm long. the ovary is superior, 3-locular, 2 grains per locule.
Fruit Seed: The fruit is a capsule that dehiscs easily at maturity. Seeds are peltate, black, 6-angled, irregularly and densely wrinkled. The weight of 1,000 grains is 2.4-3.4g.