What are the reasons for citrus cracking?
Physiological cracking
Physiological cracking is a physiological disorder caused by large fluctuations in water during citrus development. The crack is highly susceptible to the infestation of saprophytic bacteria, causing citrus to rot and losing the value of the commodity.
Excessive moisture, causing cracking and fruit drop
The main reason for citrus cracking is that the soil in the early stage of citrus is too dry, and it enters the color-changing period to the maturity stage. In the case of continuous rainfall or heavy rain, or excessive watering when it is not suitable, the soil moisture increases sharply, and the roots quickly absorb water and make citrus. A sharp increase, citrus swell pressure increased, causing the epidermis to burst and cracking.
High temperature and high humidity are the external causes of cracked fruit. The osmotic pressure distribution of citrus is uneven, and the place with high osmotic pressure is easy to absorb water and the crack is the internal cause. The fruit cracking rate is higher when the fruit is near maturity.
Thin skin variety causes cracking
1 The occurrence of physiological fruit cracking has a great relationship with citrus varieties. The sensitivity of fruit cracking has nothing to do with the size and shape of the fruit, but it is related to the length of the cell division and the structure of the peel. The varieties with short pericarpic cell division are thin, the structure is loose and easy to crack; the varieties with large cell gap are also easy to crack.
2 The degree of physiological fruit cracking has a great relationship with the geographical conditions of the orchard. Generally, the irrigation conditions are poor, and the orchards with low topography and soil weight are more serious. In addition to its internal factors, external conditions depend mainly on the extent of soil moisture content and orchard humidity throughout the year.
3 Physiological fruit cracking is also related to inadequate pollination or post-pollination dysplasia. It has been proved that the incidence of cracked fruit by artificial pollination is less.
4 Tree potential, age, and degree of development of fruit stalks also have a certain relationship with fruit cracking. At the beginning, the new shoots grow vigorously, the tree is strong, the branches are easy to grow upright, resulting in a high rate of fruit cracking, and the auxiliary fruit of the flattening The incidence is generally low.
Deficient crack
The lack of certain nutrients in the soil causes poor growth of the tree and poor fruit development, which causes the fruit to crack before and after maturity. Phosphorus, zinc, boron, manganese deficiency will show the lack of scale cracking, zinc deficiency rupture, boron deficiency cracking and manganese deficiency cracking.
Boron-deficient fruit (transverse crack)
Boron deficiency produces black spots on the fruit, causing cracks in the peel, and boron deficiency causes the fruit to cross and split.
Calcium-deficient fruit crack (longitudinal crack)
Calcium is a component of pectin calcium, which can improve the toughness of cells and the intercellular bonding. Calcium deficiency can cause citrus cracking.
Pests causing cracking
Such as citrus mites, red spiders, rust spiders, sunburn and ulcer disease, causing the skin to lose water and injury, reducing toughness and aggravating cracking.
Citrus sunburn
Severe sunburn spots become black and sag, even cracks, sponge cells die, juice granules are dry, and the value of food is lost.
Cracking caused by ulcer disease
The degree of lignification is more severe than that of the leaf lesions, and it is more solid. The crater-like cracking in the central part of the lesion is also more pronounced. In severe cases, the fruit splits.
Citrus cracking control measures
Scientific fertilization
More organic fertilizers, organic and inorganic fertilizers can be used in a reasonable combination to reduce cracking. The specific operations are:
In the early stage of citrus fruit development, Xiehua stabilized fruit fertilizer, applied water fertilizer and compound fertilizer.
Potassium fertilizer is applied in the early stage of fruit expansion, and it is best absorbed from June to July. The high-yield tree is applied with potassium sulfate or potassium nitrate 100-150 g per plant.
Apply calcium and boron fertilizers. In addition to paying attention to the application of lime and boron in the spring bud period, calcium and boron root fertilizer should be applied several times from June to July.
Strong fruit attacking fertilizer, can not apply too much speed effect fertilizer, avoiding the nutrients to absorb nutrients too fast, causing cracking fruit, can be according to "one shoot three fat" - 15 days before the shoot, the new shoot length 7 ~ 8 cm, tender The shoot turns to the green phase and is applied three times.
Water management
Paddy fields and flat bottoms should maintain soil moisture content by 60%~80% by irrigation. The orchard is cultivated by grass, and the orchard covers 15~20 cm thick grass, which can improve the ecological environment of the orchard and reduce the cracking. In the winter, the cover can be buried deep into the soil as a fertilizer with the clear garden.
Strengthening management of cultivating
In the early stage of drought, shallow tillage is 8~12 cm in the tree tray, and 15~25 cm deep in the row. After rainfall, water should be removed in time to prevent soil moisture imbalance. This can prevent the fruit from absorbing too much water and expanding the inner diameter, thus producing cracking fruit. . Control a large number of summer and autumn shoots, long short branches and appropriate short-cut topping, too many summer and autumn shoots when germinated to about 2 cm when wiped out, can effectively control the cracking fruit.
Pest Control
Prevention and control of sunburn, ulcer disease, cockroaches, rust tick, etc., reduce the occurrence of cracking of citrus caused by pests and diseases. Keep 3~4 leaves on the fruit to avoid direct sunlight and cracking fruit.
Spray plant growth regulator
After prolonged drought or rain or long drought, spray gibberellin (920) in time to keep the pericarp cells active and reduce cracking.
Precautions:
Excessive use of the concentration will result in thick and coarse skin; some people will still use 920 to prevent cracking in the late stage of sales, which will delay fruit ripening and miss the best sales season. Single use 920 generally recommends 3% of GA100ml to 350~380 kg of water, and the concentration can be appropriately reduced when the climate is dry.
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