Avocado is a fruit with high nutritional value, which is comparable to cream and has the laudatory name of forest cream.

Avocado

Avocado (avocado) generally refers to avocado.

Avocado (scientific name: Butyrospermum parkii Kotschy), deciduous tree, 10-15 m high, DBH 1-1.5 m; crown spreading, many branches and dense, stem branches stout, nodular, often curved; bark thick, irregular dehiscence, with milk. The leaves are oblong, the apex is round or obtuse, the base is round or obtuse, the upper part is dark pilose when young, the latter two sides are glabrous, the midrib is grooved above, the lower part is round and very protruding, the lateral veins are more than 30 pairs, parallel to each other, both sides are slightly raised, the reticulate veins are fine; petiole round. Pedicel puberulent; calyx lobes lanceolate, outside hairy; flowers sweet, Corolla lobes ovate, entire. The berries are globose, 3-4 cm in diameter, edible and taste like persimmons; seeds ovoid, yellowish brown, glossy, scar lateral, oblong. Flowering in June, fruiting in October.

It is widely distributed in tropical Africa. There is a large area cultivation in Yuanjiang introduction Station in Yunnan Province, China. Kernels are rich in fat, important edible oil and important industrial and mineral oil, and can be used to make margarine and soap. The fruit of avocado is a kind of fruit with high nutritional value, which contains a variety of vitamins, rich fatty acids and protein and high contents of sodium, potassium, magnesium, calcium and other elements. its nutritional value is comparable to that of cream, and even has the laudatory name of "forest cream". Generally eaten as a fruit, it can also be made into dishes and cans.

Morphological characteristics

Deciduous trees, 10-15 m high, 1-1.5 m DBH; crown spreading, many branches densely branched, stem branches stout, nodular, often curved; bark thick, irregularly dehiscent, with milk.

Leaves oblong, 15-30 cm long and 6-9 cm wide, apex rounded or obtuse, base rounded or obtuse, upper fusiform pilose when young, latter two surfaces glabrous, midrib grooved above, rounded and very raised below, lateral veins more than 30 pairs, parallel to each other, slightly raised on both surfaces, reticulate veins fine; petiole rounded, ca. 10 cm.

Pedicel puberulent; calyx lobes lanceolate, outside hairy; flowers sweet, Corolla lobes ovate, entire. Berries globose, 3-4 cm in diameter, edible, taste like persimmons; seeds ovoid, ca. 2-3 cm long, yellowish brown, glossy, scar lateral, oblong. Flowering in June, fruiting in October.

Growth habit

Avocado likes light, warm and humid climate, and is not resistant to cold. Only a few varieties can endure a short-term low temperature of 0 degrees Celsius. It is cultivated at 40 °S-40 °N in the world, with an average annual temperature of 20-25 ℃. Cold resistance varies with different varieties (strong cold tolerance of Mexican line, weak cold tolerance of Guatemala and West Indies), cold-resistant varieties can tolerate-6 ℃ low temperature, low cold resistance varieties will dry up at 0 ℃ low temperature. Need annual rainfall of more than 1000 mm, shallow roots, fragile branches, can not withstand strong winds, strong winds can lead to reduced production, strong adaptability to the soil.

Geographical distribution

Avocados are native to Mexico and Central America, and then widely cultivated in California, so California has become the largest producer of avocados in the world, growing in the tropics and subtropics all over the world. however, it is most cultivated in the southern United States, Guatemala, Mexico and Cuba, and has formed three major populations: Mexico, Guatemala and West Indies. A small amount of cultivation is found in Guangdong, Hainan, Fujian, Guangxi, Taiwan, Yunnan and Sichuan in China.

Reproduction method

Avocado can be propagated by seed or grafting. When sowing, the seed coat should be peeled off and germinated in the sand bed. The plant should be planted in a place with deep soil layer, good drainage and shelter from the wind. The suitable row spacing is 5 * (6-7) meters, and mixed planting of varieties can ensure pollination. Grafting is best raised in containers, and the seedling can be grafted with a diameter of 0.8-1 cm.

Cultivation techniques

Colonization

50-60 cm between seedlings, 5-6 m between rows, 3-4 years or 4-6 years after grafted seedlings.

Overlay

Avocado is a fruit tree that grows in tropical rain forest and in competitive sunlight. It grows rapidly in the environment of high temperature and humidity, but grows slowly if the environmental conditions are not available. Therefore, the cultivation of avocado abroad mainly emphasizes growing grass or planting green manure near the plant at the initial stage, and covering a large amount of organic matter in the topsoil, forming a rainforest rhizosphere environment similar to that of origin, and stabilizing the ecological conditions of the rhizosphere. Promote the reproduction of microorganisms that can inhibit root rot activity. Therefore, from the young tree stage to the tree itself can form a cover layer through fallen leaves and before the occurrence of root rot, it is particularly important to carry out tree plate young trees. Begin to cover in winter, replenish the thickness in spring, and form a good cover in summer. Rhizosphere mulching can also reduce soil water evaporation, reduce the damage of dry heat to avocado, lower soil temperature in summer, increase soil temperature in winter, increase soil organic matter, reduce weeds and prevent soil erosion on sloping land. But keep the soil from getting too wet during the rainy season.

Fertilizer application

Nitrogen fertilizer is routinely applied more than 4 times a year, usually by withdrawal or through irrigation system. In the young fruit stage of adult trees, 50 kg organic fertilizer and 50 g compound fertilizer are applied, and the quantity is doubled after harvest. When the leaf analysis indicates that phosphorus and potassium fertilizer is applied when the content of phosphorus and potassium is low, zinc can be applied or foliar spraying zinc in some types of soil, and spraying is the most effective when new leaves are developed in spring. the most effective way for crops to grow on calcareous soil or low oxygen content soil is to inject chelating iron solution into the root zone. The amount of nitrogen used should be reduced when there is nitrogen in some soil and irrigation water, and nitrogen fertilizer should be applied when there are few new leaves growing on trees and when the leaves are gray or bear more fruit.

Draining water

Avocado is evergreen all the year round, and it is necessary to keep the rhizosphere soil moist throughout the year, and it is very sensitive to soil drought. once there is a lack of water, the physiological function is blocked, and the tree is weak, which leads to falling leaves and fruit, and the cold resistance is reduced in winter, so it is necessary to irrigate properly during drought. From fruit setting to fruit ripening, it is very important to maintain soil moisture. If the young fruit falls off seriously in the first month of fruit setting due to drought. On Hainan Island, the dry and hot weather from April to May caused serious fruit drop of avocado. Therefore, if the garden soil begins to crack for 10-20 days, it should be irrigated in time; if the rainfall is lower than transpiration and evaporation for a long time, supplementary irrigation should also be added. However, irrigation should be just right, not only sufficient, but also avoid excessive, generally soaking through the soil is appropriate, if too wet, it will aggravate root rot, but also reduce the content of soluble solids in fruit. It is best to use sprinkler irrigation or drip irrigation. Flooding irrigation may cause root rot, and drip irrigation can save 50% of water and 60% of water. Some dry leaves begin to curl, and the crown can be sprayed with water. Pay attention to drainage in the rainy season, especially in flat orchards.

Disease prevention and cure

Anthrax

Harm: anthracnose is an important disease of avocado, which mainly harms mature fruit, and can also infect leaves, twigs, flowers and young fruits, cause fruit drop and fruit rot, and shorten shelf life. Generally, the disease occurs after fruit ripening, and the diameter of the spot before ripening is not more than 5 mm, round, slightly sunken, brown or black. When the conditions are suitable, the disease spot expands rapidly, the depression is obvious, the center of the disease spot appears radiant cracking, and finally the disease spot is connected, and the pink conidia pile appears. As the fruit ripens gradually, pathogens can invade the pulp, causing black-green dry rot.

Prevention and control: remove the diseased branches in the orchard, cut off the diseased leaves, eliminate the source of infection, and carry out low-temperature pretreatment and low-temperature storage as soon as possible after harvest. Almost all avocado varieties are sensitive to the pathogen of the pathogen. The key to prevention and control is to reduce the occurrence of other fruit diseases (especially tail spot disease) and avoid mechanical damage in fruit transportation.

Scab disease

Harm: the damaged fruit produces a slight round brown scar at the beginning, then turns brown to light purple, and after ripening, the disease spot is United, the center is sunken, and the pericarp is rough. After infecting the fruit, the disease did not affect the flavor quality, but the appearance quality decreased seriously. In the young fruit stage, if the weather is cold and wet, the disease occurs seriously. It can also damage the leaves, the damaged leaves appear brown spots, the leaves wrinkle, the disease spots further develop into a star shape, and the center is perforated. Leaf damage often occurs at the top of the crown, and the disease spot is mostly in the leaf back texture, the disease spot is small, discrete and discontinuous, and it is not easy to observe. The petiole and branchlet disease spots are oval and are easily confused with the spots caused by shell insects.

Prevention and treatment: cut off diseased branches to reduce pathogens, spray Bordeaux solution or other copper preparations.

Cercospora spot disease

Harm: it can harm leaves, stems and fruits. Infect the fruit, form withered spots on its surface or cause epidermis cracking, cracks can cause anthrax infection. When infecting the leaves, the withered spots of 2 to 5 mm appeared on the leaf surface at first, the first brown, then turned purple, the spots extended to both sides of the leaves, the shape was irregular, and when serious, the withered spots joined together to form larger withered spots.

Control: use chemical control, spray copper preparation and azoxystrobin on branches and fruits.

Small hole shell fruit rot

Harm: the symptom of susceptible fruit is not obvious before picking, the disease spot is small and shallow, and the symptom becomes obvious in the process of fruit harvest and softening. Small and irregular brown to red disease spots appeared in the initial pericarp. Due to the bacteria invading the vascular bundles, brown stripes could be seen in the pulp after peeling off, and then purple-brown irregular disease spots appeared in the pedicel. With the ripening of the fruit, the epidermal spots gradually grow, blacken and sunken, and the brown pericarp is covered with grayish-brown mycelium and spores, which exudes brown pulp and juice and gives off a bad smell.

Prevention and treatment: cut off dead branches and tips, remove dead wood and diseased fruit, choose sunny weather to pick fruit, strengthen the nutrition of fruit trees and reduce the occurrence of other diseases.

Pedicle rot

Harm: the fruit pedicel is first susceptible to disease, slightly withered around the fruit pedicel, with the fruit ripening, bacteria invade the fruit, around the fruit pedicel appears obvious black rot, the disease boundary is obvious. And gradually spread to the whole fruit surface, the bacteria invaded the pulp, causing tissue discoloration, degradation, and emitting an unpleasant smell, thus reducing the fruit quality.

Prevention and treatment: pathogens can survive on host disease remains. Therefore, it is necessary to eliminate the source of infection in time to avoid the accumulation of diseases and disabilities in the park. Watering the lower part of the orchard can prevent the germs from moving to the higher fruit. Eliminating water stress can reduce infection. Covering with film or weeds under the tree can accelerate the decomposition of the diseased body. In addition, do not harvest in cloudy and rainy days.

Phytophthora fruit rot

Harm: Phytophthora can cause fruit rot, stem ulcer and rot both before and after harvest. Black round disease spots often appear near the pedicle of susceptible fruit, and the pathogen can invade the pulp.

Prevention and treatment: cut off the withered branches and stems, clean the orchard, remove the fallen fruit and diseased fruit, and prevent the pathogen from re-infection. Cover with thick mulch under the plant to inhibit the spread of bacteria in the soil.

Soot disease

Harm: the surfaces of fruits, leaves and stems are covered with black soot-like hyphae and spores and grow on honeydew secreted by wax scale and whitefly.

Control: the key is to control pests and reduce the production of honeydew. A better method is to use natural enemies for biological control.

Main value

Industry

Kernels are rich in fat, important edible oil and important industrial and mineral oil, and can be used to make margarine and soap.

Edible

Nutritive composition

Fruit is a kind of fruit with high nutritional value, which contains a variety of vitamins, rich fat and protein, and high contents of sodium, potassium, magnesium and calcium.

Efficacy effect

Anti-oxygen and anti-aging: avocado is rich in glyceric acid, protein and vitamins, moisturizing but not greasy, is a natural antioxidant aging agent, not only can soften and moisturize the skin, but also can shrink pores, the surface of the skin can form a milky isolation layer, can effectively resist sunlight, prevent sunburn. The avocado oil extracted from nuts is rich in nutrients and rich in vitamin E, magnesium, linoleic acid and essential fatty acids, which helps to strengthen the cell membrane and delay the senescence of epidermal cells.

Breast enhancement: the rich unsaturated fatty acids in avocado can increase the elasticity of chest tissue, vitamin A can promote female hormone secretion, vitamin C can prevent chest deformation, and vitamin E can help chest development.

Protect the liver: avocados have been found to contain effective chemicals that may protect the liver, a discovery that will help people invent new drugs to treat liver diseases.

Beauty: avocado pulp has good affinity with human skin, is easily absorbed by skin, has strong absorption to ultraviolet rays, and is rich in vitamin E and carotene, so it has good skin care, sunscreen and health care.

Relieving diabetes: avocado pulp sugar content is very low, which is 1% of banana sugar content. It is a rare high-fat and low-sugar food for diabetics, and drinking with peel water can alleviate diabetes.

Protect uterine health: avocados protect women's uterus and cervix. Eating one avocado a week can balance estrogen, lose excess weight during childbirth and prevent cervical cancer.

Baby food supplement: avocado is one of the good baby food supplements.