Fruit cracking of navel orange and its control

First, reason 1. Climate: summer high temperature and drought damage pericarp tissue and cells; excessive rainfall after long drought, resulting in excessive swelling and pressure, damage pericarp; 2. Pericarp factors: peel tends to mature, pericarp thinning, pulp softening; sugar accumulation in fruit juice, accelerating water absorption, increasing swelling pressure; 3. Cultivation factors: excessive P application; dryness and humidity of soil moisture; weak tree power; shallow root system 4. Biological reasons (1) the proportion of flower-leafless flower and leafy single flower is higher. The leafy single flower and fruit is the largest, the most partial, the most petal, and the most easy to split fruit. Among the inflorescence branches, the 2nd-3rd fruit dehiscence is the least. When the temperature is high before and after flowering, promote the vertical growth of young fruit, not easy to crack fruit; (2) fruit-flat fruit shape is easy to crack fruit, long fruit shape is not easy to crack fruit. The apical skin is thin and easily dehiscent. The easily dehiscent fruit with more cysts; (3) umbilical-large navel fruit. The order of navel shape and fruit dehiscence was sunken navel > flat navel > closed navel > convex navel. The more secondary fruit capsule valves, the larger the size, the easier to crack fruit. 2. Select varieties and strains of high quality but not easy to crack fruit; 2. Increase the application of organic fertilizer to cultivate deep and developed roots and enhance tree potential; 3. Increase the application of N fertilizer and K fertilizer to enhance pericarp vigor and thickness; 4. Do a good job in water regulation in summer and autumn, timely drainage and irrigation 5. According to flower fruits and vegetables, first remove leafless flowers and fruits, leafy single flowers and fruits, flat fruits. If you do a good job of fruit thinning, the fruit cracking rate can be controlled to less than 5%; 6. Cultivate high-quality flower patterns, promote and enrich inflorescence branches, each inflorescence branch bears 3-4 flowers and 4-6 leaves; 7. Strengthen the tree potential to make the tree storage nutrients sufficient. Inflorescence tree short truncated flower number, reasonable fertilizer and water management in autumn and winter; 8. Prevention and treatment of fruit cracking ① lack of water and nutrition before and after sprouting in spring and before and after flowering, indicating that serious fruit cracking will occur in summer, suitable leaf nitrogen spraying and corresponding irrigation; the sharp change of soil moisture in summer and autumn of ② is the direct cause of fruit cracking, irrigation prevents the soil from being too dry without affecting the quality; ③ applied 5-10ppmGA3 solution on the top of fruit in early summer.