1. The method of keeping tree fresh-keeping, also known as fresh fruit preservation, is the method of applying a certain concentration of stable fruit agent to the tree body when the fruit is basically ripe, so as to make the fruit safely overwinter in the tree. The technical point is: Citrus fruits are used in the harvest period (December) in the month of December and December, and the following year in January. They use 30 ppm of 2,4-d and 20 ppm respectively. The 920 and 0.2% potassium dihydrogen phosphate solution was sprayed one time on the hanging fruit trees, leaving the trees fresh for 2-4 months, and the natural fruit drop rate was only 9.6-26%. In December of the same year, in the following January and February of the following year, oranges were sprayed with 20 parts per million of 2,4-d solid fruit, and 2.5 kg of plant ash was applied to the root of each fruit tree. It can delay the ripening of fruits and leave it to harvest in March of the following year, with a stable fruit rate of 95%. 2. The ash-preserving method of plant and tree ash The use of ash has the characteristics of moisture absorption and heat absorption, heat preservation, and inhibition of microbial activity to keep fresh oranges, and is still beautiful and beautiful after 120 days of storage. Collect dry, cool, clean and free of impurities and ash for use. A layer of 1-2 cm thick grass ash is laid on the bottom of the container, and then a layer of fruit is placed evenly. The fruit pedestal is upward, then a layer of grass ash is laid, and a layer of fruit is put on, so that it is slightly lower than the container to install the fruit. The 10th floor is limited, and the top layer is covered with ash. Move containers into indoor storage. 3, pine needle preservation method? Pine needles, also known as pine, antibacterial, anti-aging effect. For the preservation of fresh oranges, it is required to collect fresh water-free, clean pine needles without branches. According to the method of preserving grass ash, pine needles and oranges are successively loaded into containers and placed neatly. The top layer covers pine needles 2 cm thick. Stored in the greenhouse, the freshness of fresh fruit to more than 85% in the following year. 4. Galangal Preservation Method: The fruit is coated with Gaoliang ginger sap, which has good antisepsis and preservation effects. The method is: according to 1000 kilograms of fruit with 1 kg of galangal dry goods, chopped and added 10 kilograms of water and boiled for 45 minutes to obtain 7 kilograms of juice, then add bleached shellac 1.5 kilograms and water 3-5 kilograms of solution to mix, The mixture was filtered while hot and coated with fruit after cooling. Put the liquid on the fruit and put it in a cool and ventilated place. After the fruit surface liquid is allowed to dry, it can be put into a clean container, put it in a cool and ventilated room, and adjust the temperature and humidity in due course. After 90 days of storage, the fruit was plump, bright and mellow, with a good fruit rate of 92%. 5. Biogas Preservation Method: The pre-stored oranges are loaded into containers and put into the storage room for stacking. Take a hollow plastic tube with a diameter of 8 mm into a fruit pile, and connect the other end with a biogas digester. Put a biogas every 2-3 days. Normally 500 kg of fruit put 0.4 cubic meters of biogas, which can effectively reduce the fruit pile. Oxygen content, play a role in preservation and preservation, can be stored for 130 days. 6, plant carbon preservation method to take charcoal or bamboo charcoal 50%, sodium chlorite 25%, ferrous sulfate 15%, zinc oxide 10%, mixed crushed and sieved, add a small amount of water mixing, made of carbon 5mm in diameter Granules, ready-to-eat preservatives after drying. Preservatives are packaged into 10-20 g pouches using breathable materials such as paper or cloth. Then, according to the amount of 3% of the weight of citrus fruit, the charcoal bag and the fruit are loaded into a container or a storage room, which can not only decompose harmful substances such as ethylene, alcohol, aldehyde and the like, but also prevent mold and corrosion, and has no toxic and side effects on the fruit. 7, ozone preservation law? Ozone has bactericidal, deodorant, mildew and reduce the efficacy of metabolic activity of fruits and vegetables, can be obtained by air discharge technology. The citrus fruit is loaded into a container and put into a normal warehouse for stacking (130 kg of fruit per cubic meter of space). Then use the 220V, power 30w small air-discharge preservation machine hanging or wall hanging room, start the machine through the high-pressure discharge, so that the oxygen in the indoor air to form ozone, work 90 minutes per day, fruit preservation period of up to 90 days.