This year's leeks, a large number of dry tip yellow leaf phenomenon, seriously affecting the quality of goods. Most of the yellow tips of leek are not caused by infectious diseases. Spraying fungicides has no effect. The reason why physiological yellow tips of leek occur is as follows:
First, the suitable temperature for the growth and development of leeks is about 25°C, and the relative humidity of the air is about 60%. In June of this year, the weather was hot and dry. The temperature was generally above 30°C and the relative humidity was below 50%. This climate condition leads to a large loss of water in the leaves and dry yellow leaves. In July-August, there was more rainfall. In the case of high temperature and high humidity, the yellow leaves of the leaves are also sharpened.
Second, leeks are suitable for neutral soil conditions, but the current application of a large number of acidic fertilizers (such as human waste, cake fertilizer, ammonium sulfate, etc.) cause soil acidification. Some neutral fertilizers such as potassium sulfate, potassium chloride, in use, potassium ions are absorbed, leaving acid roots in the soil can also cause the acidification of the soil. Due to the acidification of the soil, the leek grows slowly and is weak and the outer leaves yellow. In addition, in most areas, there is an excessive amount of fertilizer applied, resulting in an excessive concentration of soil solution, burning of roots, and sharpening of yellow leaves of leeks. Improper application of fertilizer is an important reason for the abnormal growth and development of leeks.
Third, in poorly ventilated plots, or in protected areas, a large amount of carbon fertilizer or farm manure will release a lot of ammonia gas. Acidified soil will release a large amount of nitric acid gas. These poisonous gases poison the leeks and cause yellow-tip dryness.
Fourth, due to the application of less calcium in the soil, or watering is not timely, it will cause yellow leaves of Chinese chive heart dead. The soil lacks magnesium and yellow leaves of the leeks. The soil lacks boron, and the center leaves yellow. When there is excessive boron in the soil, the tips of the leaves will die. When the manganese is surplus, the heart leaves will be yellow and the outer leaves will yellow. In the current soil, due to lack of calcium and boron elements, the yellow tip of the leeks is mostly caused.
The following measures are taken to prevent the yellow tips of leek.
Summer heat season, the application of shade nets to reduce the temperature and light intensity; appropriate watering and drainage, to maintain the proper humidity of the soil; fertilizer should pay attention to increase manure, reduce the amount of fertilizer; each chase fertilizer, should not exceed 25 kg per mu; Pay attention to ventilation; apply no-tillage fertilizer in summer to loosen and penetrate the deep 30-40 cm soil, promote root growth and development, and enhance absorption capacity; apply calcium, magnesium and other fertilizers to supplement calcium, magnesium and other elements in the soil; every 20 days A natural brassin, Shuofeng 481, was sprayed once to promote the physiological function of the leaves and reduce the dry tip of yellow leaves.
Visible Spectrophotometer,Lab Fluorescence Spectrophotometer,Single Beam Spectrophotometer,Uv Spectrophotometer
Unimedsume Trading Co., Ltd , https://www.ums-labmed.com