How to prevent lychee fruit cracking? Calcium application is an effective method
In recent years, lychee fruit cracking (in cultivars such as Nuomici, Guiwei, Sanyuehong, Lusha, and Tianyan) has become fairly common. Lychee fruit cracking mostly occurs during the fruit enlargement stage, generally at 20-30% in normal years, and reaching 50% in severe cases. There are many domestic reports on the causes and mechanisms of lychee fruit cracking, and many researchers have mentioned...
In recent years, lychee fruit cracking (in cultivars such as Nuomici, Guiwei, Sanyuehong, Lusha, and Tianyan) has become fairly common. Lychee fruit cracking mostly occurs during the fruit enlargement stage, generally at 20-30% in normal years, and reaching 50% in severe cases.
Regarding the causes and mechanisms of lychee fruit cracking, there are many domestic reports, and many researchers have mentioned that lychee fruit cracking is related to the mineral nutritional status of the lychee, especially calcium nutrition status.
Our survey shows that southern soils are acidic, the ripening period coincides with the rainy season, and during planting and management growers favour nitrogen fertilizer while neglecting phosphorus and potassium fertilizers and overlooking the supplementation of medium and trace element fertilizers, resulting in severe soil acidification, compaction and poor tilth, frequent nutrient deficiency symptoms and root diseases. Together with improper cultivation and damage from pests and diseases, these are the main external factors causing lychee fruit cracking.
Therefore, we set up demonstration trials in the Zengcheng area of Guangzhou and in Maoming, respectively, using soil conditioners and sugar alcohol chelated calcium fertilizer to improve the mineral nutritional status of the trees and to supplement calcium to prevent fruit cracking. Among these, the soil conditioner was Futaiwei organic calcium powder, made from oyster shell powder through high-temperature calcination, with an effective calcium content of 45%, capable of neutralizing acidity and improving soil. The sugar alcohol chelated calcium fertilizer, whose trade name is Fruit and Vegetable Calcium Fertilizer, solves the problem of calcium mobility in the phloem and can increase the calcium absorption rate of fruit trees and the utilization rate of calcium fertilizer. The test lychee cultivars were Nuomici, Guiwei and Baitangying. The measures taken were: Measure 1, Sifeng, Zengcheng, applying the soil improver Futaiwei organic calcium powder as a base fertilizer in autumn, and spraying sugar alcohol chelated calcium 5 times during the young fruit stage and the enlargement stage; Measure 2, Yinzhencheng, Zengcheng, starting from the second physiological fruit drop, spraying Fruit and Vegetable Calcium Fertilizer on the leaves at an interval of 2 weeks, for a total of 5 sprays; Measure 3, Huazhou, Maoming, before the second physiological fruit drop, applying Futaiwei organic calcium powder as a base fertilizer and spraying Fruit and Vegetable Calcium Fertilizer on the leaves, spraying Fruit and Vegetable Calcium Fertilizer once a week after fruit drop, and spraying Fruit and Vegetable Calcium Fertilizer once every 2 weeks during the enlargement period, for a total of 4 sprays.
The survey shows that in the Sifeng demonstration area of Zengcheng, the control orchard had more fruit cracking. In the treatment sprayed with Fruit and Vegetable Calcium Fertilizer alone, fruit cracking was significantly reduced, and there was less on the outer part of the plant than inside, possibly related to ventilation and light penetration. There was no obvious difference between the supporting measures of applying soil improver plus foliar spraying and spraying Fruit and Vegetable Calcium Fertilizer alone; in these two treatments some fruits had already begun to colour, and they were uniform in size. At the mature harvest stage, the fruit cracking rate of the control reached 30%, while the fruit cracking rates of the two treatments were significantly lower than the control, and their appearance, fruit shape, colour and lustre, sweetness, taste and storage performance were all superior to the control orchard.
In the demonstration area in the Maoming region, the lychee fruit cracking rate under the supporting measures of basal application of Futaiwei organic calcium powder (soil improver) plus foliar spraying of Fruit and Vegetable Calcium Fertilizer (sugar alcohol chelated calcium) was 0.53%, the fruit cracking rate with foliar spraying of Fruit and Vegetable Calcium Fertilizer alone was 3.21%, and the fruit cracking rate of the control reached 8.33%.
Conclusion: Soil improvement with Futaiwei organic calcium powder and foliar supplementation of calcium fertilizer can effectively reduce lychee fruit cracking, which shows that exogenous calcium supplementation has a certain effect on preventing lychee fruit cracking. To achieve the ideal effect, attention must be paid to the number and timing of applications. Futaiwei organic calcium powder is best applied together with the autumn base fertilizer, and Fruit and Vegetable Calcium Fertilizer is best used 4 to 5 times after physiological fruit drop in combination with pesticide spraying.
Since the causes of lychee fruit cracking are multifaceted and involve integrated control techniques such as water and fertilizer management, it cannot be prevented by calcium fertilizer alone; comprehensive management measures are necessary.