First, onion growth on the temperature requirements Onions have strong adaptability to temperature, seeds and bulbs germinate slowly at a low temperature of 3 to 5°C, germinate rapidly at temperatures above 12°C, and seedlings grow at a temperature of 12 to 20°C, leaves at a temperature of 18 to 20°C, and bulb expansion. The high temperature is generally 20 ~ 26 °C, below 15 °C can not be expanded, 15 ~ 20 began to expand, 21 ~ 27 °C in the best growth. Plants above 27°C were strongly inhibited and went dormant. Onions have strong cold resistance and adaptability, especially some spicy varieties, strong drought tolerance, the outer leaves can tolerate -7 °C low temperature, the plants can tolerate lower temperatures under soil protection, and the cold resistance of bulbs is significant after maturation Enhanced. There are some differences in the response of temperature between onion shoots and roots. It is observed that at 0°C, the growth rate of roots is faster than that of leaves. When the temperature is 10°C, the growth rate of leaves is faster than that of roots. Planting mother plants and growing spring onions should be planted in advance so that the function of the roots can be restored before the leaves are developed. The onion is a greenish vernalized crop, which induces a lower temperature for flower bud differentiation. The length of time required for low temperature varies depending on the species, cultivation conditions, and the size of the plant's nutritional body. Most varieties in the seedling stem diameter greater than 0.7 cm, or bulb diameter greater than 2.5 cm, at 2 ~ 5 °C low temperature conditions, takes 60 to 70 days; southern varieties in the same temperature conditions take 40 to 60 days, while the northern type Variety, under the same temperature conditions need 100 to 130 days. Therefore, the mother plants used for seed collection in the north should be stored at a low temperature of 2~5°C so that they can feel the effects of low temperature during storage, and they can successfully twitch and blossom. Onion twitching and flowering require a higher temperature, suitable temperature is 15 ~ 25 °C. Flowering and seed development require higher temperatures, typically 25-30°C. Second, onion growth on the moisture requirements The onion has a shallow root system and weak water absorption capacity. In the germination period, the seedling growth period, and the bulb expansion period, sufficient water supply is required. However, before the wintering of the seedlings, the irrigation should be properly controlled to prevent the seedlings from growing too thick or stout. Within 1 to 2 weeks before harvesting, irrigation should be gradually reduced to enrich the bulb tissue and improve product quality and storage stability. Post-harvest bulbs require a dry environment. Excessive temperatures can easily cause storage problems. The onion leaves have wax powder, which has little transpiration and is relatively drought-resistant. It is suitable for air relative humidity of 60%~70%, and still grows well when the relative humidity of the air is 45%~55%. Excessive air humidity can cause various diseases. Third, onion growth requirements of light Longer sunshine hours are not only the necessary conditions for inducing flower bud differentiation, but also the main conditions for the formation of bulbs. Extending the light time can speed up the development and maturation of the bulb. The requirements for the number of hours of sunshine due to bulb formation vary from species to variety. Short-day varieties and early-maturing (early-maturing) varieties develop bulbs under shorter daylight conditions below 13 hours; long-day and late-maturing types (late-maturing species). Varieties must be able to form bulbs under long daylight conditions of about 15 hours; in some intermediate varieties, bulb formation requires less stringent sunshine hours. In northern China, most of them are long-day late-maturing varieties, while in the south, they are mostly short-day early-maturing varieties. To this end, the introduction of species should first consider whether the characteristics of the species meet the local sunshine conditions. If a species that requires long days is rushed to the south, it must wait until around the summer solstice to meet the requirements of the formation of bulbs. On the contrary, if the short-day varieties that can only form bulbs under short daylight are introduced to the north, the bulbs will be formed too early if the plants have not grown up sufficiently. Because the leaf area is small and there is not much accumulated nutrients, the bulbs cannot be fully expanded. And cut production. Onion during the reproductive period, the requirements of light intensity is lower than that of vegetable vegetables, higher than the general leaf vegetables and root vegetables, moderate light intensity. Fourth, onion growth on the soil requirements Onions require fertile, loose, and water-rich soils. Soil viscosity is not conducive to hairy roots and bulb growth; sandy soils have poor water retention and fertility and are not suitable for the cultivation of onions. Onions are suitable for neutral soils and can also be adapted to slightly saline-alkaline soils. However, the seedling stage is more sensitive to saline-alkali response. Yellow seedlings and dead seedlings are easily induced in the saline-alkali soil. The suitable soil pH is 6-8. Fifth, onion growth nutrient requirements Onion is hi-fertilizer and requires higher soil nutrient content, but in fact, the amount of fertilizer is moderate. The standard application rates of nitrogen, phosphorus, and potassium per mu are 12.5 to 14.3 kg of nitrogen, 10 to 11.3 kg of phosphorus, and 12.5 to 15 kg of potassium. It can be seen that onion has the greatest potassium uptake, followed by nitrogen. Nitrogen fertilizer was the main seedling stage. Potassium fertilizer was applied during the expansion of bulbs, which could promote the division and enlargement of bulb cells. The use of phosphate fertilizer is beneficial to the absorption of nitrogen fertilizer and can improve product quality, but the application of phosphate fertilizer should start from the seedling stage. Nitrogen deficiency or excess has a great influence on the growth and development of onion. Nitrogen deficiency, growth inhibition, starting from the outer leaves of the yellow, in severe cases will die, but the root remains active. In the early stages of the formation of the plant's vegetative body (leaves and bulbs), the requirement for nitrogen is high, and this is also the critical period for the need for nitrogen. After entering the bulb formation period, if the nitrogen supply is insufficient, the bulbs will expand badly, the shape will be thin, and even the growth of the bulbs will be restrained, and the inherent high yield capacity cannot be fully utilized. On the other hand, if nitrogen is absorbed excessively, the leaf color is dark green, the developmental process is slow, and the leaves are greeted with greenness, which delays maturation and is susceptible to disease. In general, nitrogen in the soil at 30 to 60 mg/kg is prone to physical disorders. Because when the nitrogen is supplied too much, due to excessive accumulation of water-soluble nitrogen in the scale, calcium deficiency is exhibited, and heart rot (internal scale calcium deficiency and rot) and muscle rot (external scale decay) are liable to occur. The role of trace element boron can not be ignored, the lack of boron onion will cause new leaf chlorotic malformation, texture brittle; trapezoidal cracks occur in some leaf sheath; bulb loose, severe heart rot. Boron-deficient areas increase the production of boron, improve quality, and have obvious effects. Disclaimer: Some articles in this website have been transferred from the Internet. If you are involved in third party legal rights, please inform this website. phone Anti Static Protective Clothing Hongxing Factory Anti Static Protective Clothing,Anti Static Suit,Anti Static Raincoat,Anti Static Clothes Dongying Hong Xing Labor Protection Products Co.,Ltd. , https://www.hongxinglabor.com
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