Why does summer cabbage not contain heart

Why doesn't summer cabbage care? How to carry out prevention and control? Please give guidance on the cultivation of Chinese cabbage in summer, which often appears the phenomenon of not rolling leaves and not wrapping the heart, which affects its commodity value and edible value, which is a problem often encountered in summer Chinese cabbage cultivation. The reasons are as follows: first, the variety is not the right way. Second, the temperature is uncomfortable. Chinese cabbage likes mild climate, and the most suitable rosette stage is 17-22 ℃. If the temperature during the rosette period is too high and the growth is too prosperous, it will delay or unfruitful; if the temperature is too low (heading period), the accumulated temperature below 12 ℃ for 5-7 days can not be satisfied, then the heart leaf growth is very slow. Third, there is not enough fertilizer and water. Chinese cabbage grows fastest in the heading period, absorbs the most water, and absorbs 89% of the total absorption of nitrogen, phosphorus and potassium. Prevention and control measures: 1. Variety selection. Summer Chinese cabbage should choose early hybrid varieties that are resistant to high temperature, high humidity and disease and insect pests. 2. Rational fertilization. Farm manure and phosphorus and potassium fertilizer should be applied during the heading period, and mature human and animal manure and potassium dihydrogen phosphate should be applied once in the early and middle stages of pelleting. 3. Scientific water supply. During the heading period of Chinese cabbage, it is necessary to maintain a uniform and adequate supply of water to keep the soil moist. 4. Control diseases and insect pests. During the heading period of Chinese cabbage, the leaves must be examined to find the damage of diseases and insect pests, and 1500 times Nongdilol and 2500 times clozole were sprayed 2-3 times immediately. Spray once every 10-15 days, if a virus disease occurs, 800 times of virus An aqueous solution or 600 times of virus Bike aqueous solution should be added. 5. Foliar spraying fertilizer. During the enveloping period, special vegetable fertilizer was sprayed on the leaves every 7-10 days, or a mixture of 0.1% magnesium sulfate, 0.3% urea and 0.3% potassium dihydrogen phosphate was sprayed 2-3 times in a row to wet the leaves evenly. Click to get more cabbage planting techniques click to get more vegetable planting techniques