Causes and control of fruit cracking of litchi without commercial value

Litchi fruit cracking is a common phenomenon in the late ripening period, especially for litchi varieties with thick kernels, such as glutinous rice, when serious, the fruit cracking rate is as high as 30%, 50%. Fruit growers often talk about the fruit of their mouth, but the money they get is "cracked" in vain.

Litchi fruit cracking

The main cause of litchi fruit cracking is the imbalance of fertilizer and water in the process of fruit development. The two elements that have the greatest influence on the development of litchi fruit are calcium and potassium. Calcium is an effective ingredient of pectin in the pericarp. If calcium is lacking, the connection between the pericarp cells and cells is poor, and the elasticity and strength of the cell wall become weaker. If the pulp grows too fast or absorbs too much water, the pericarp will be broken and split. In addition, calcium also bears the important task of regulating the water balance in the fruit. If calcium is deficient, the water in the fruit is out of balance. During drought, the fruit loses water, the pericarp is prone to sunburn and stops growing, and when the pulp grows, the pericarp will rise and crack. On rainy days, the fruit will break the pericarp because of its high sugar content. Litchi pulp development requires a large amount of potassium, if the potassium supply is uneven, the pulp growth slows down or even stops when potassium is deficient; when potassium is too long, the growth is accelerated suddenly, breaking the pericarp and cracking the fruit.

To find out the cause of fruit cracking, efforts should be made on two fertilizers and one water in prevention and control, first of all, to ensure that calcium continues to enter the pericarp. In general, lime is used as calcium fertilizer, which is evenly scattered under the crown before flowering, 1.5 kg for 3-5-year-old trees and 2.5 kg for 10-year-old trees. The second is the balanced supply of potash fertilizer. It is necessary to apply potash fertilizer in a timely and appropriate amount. For trees with 20 kg of fruit, 0.5 kg of potassium chloride is applied per tree, 0.2 kg of potassium chloride is applied at the time of fruit setting, 0.15 kg of potassium fertilizer is applied for 25 days or so, and then the last 0.15 kg is applied until the fruit has almost reached its maximum. The third is to ensure a uniform supply of water in the whole process of fruit development. In the dry season, the soil water content is low, which is not conducive to calcium absorption and transportation. While watering more, we can adopt the method of applying calcium fertilizer outside the root. 2/1000 concentration of calcium chloride or calcium nitrate solution is directly sprayed on flowers and fruits. The spraying times depend on the weather. Generally, it is necessary to prevent excessive water absorption in rainy seasons, except to do a good job of orchard drainage. Especially when the fruit finally expands (the fruit turns red), control the growth of the root system to prevent the absorption of too much water. The experience of Huangjiang in Dongguan is that around May 25, the ring has been cut twice, and the spiral ring has been used to ensure that the wound does not heal before the "dragon boat water" comes.

Taking the above measures, coupled with appropriate fruit thinning, timely prevention and control of diseases and insect pests, litchi fruit cracking can be reduced to a minimum.