Method for relieving freezing injury of citrus by fermenting trimmed branches to generate heat

Abstract

The invention relates to the technical field of citrus planting, and discloses a method for reducing citrus freeze injury by fermenting trimmed branches to generate heat, which comprises the following steps: step 1, uniformly mixing citrus branches and leaves, cow dung, rape seed cake, phosphate fertilizer and compost leavening agent in proportion to prepare a fermented mixture; and step 2, uniformly spraying a nitrogen fertilizer aqueous solution into the fermentation mixture, uniformly turning and mixing, and preparing a fermentation heat generation pile in an orchard, so that citrus in low-lying places in winter is prevented from being frozen, freezing damage loss is prevented or reduced, and the method is low in preparation cost, safe, harmless and simple to use.

Description

Technical Field

[0001] The invention relates to the technical field of citrus planting, and in particular to a method for reducing citrus frost damage by fermenting and generating heat through pruned branches. Background Art

[0002] Citrus is not a very frost-resistant fruit tree. Lemon branches and leaves can only withstand low temperatures of -3℃ to -5℃, sweet orange and grapefruit branches and leaves can only withstand low temperatures of -6℃ to -7℃, broad-skinned citrus branches and leaves can withstand low temperatures of -7℃ to -9℃, and all citrus fruits can only withstand low temperatures of -2℃ to -2.5℃. The extreme minimum winter temperatures in citrus producing areas in Zhejiang, Shaanxi, Hubei, Hunan, Jiangxi, and Guizhou are all lower than the temperature that citrus can tolerate. Although the frequency of extreme minimum temperatures usually occurs once every 7 to 10 years, each time it occurs, it causes serious losses to citrus production.

[0003] In Citrus Science (Edited by Deng Xiuxin and Peng Shuang, China Agricultural Press, August 2013), it is written: Zhou Junhui et al. (1996) counted the low temperature years in the middle and lower reaches of the Yangtze River from 1450 to 1992, a total of 540 years, and found that citrus suffered frost damage in 86 years, an average of 1.56 times every 10 years. The frequency of frost damage is higher in the northern citrus production areas and citrus orchards at high altitudes in the mountains. In years with low temperatures, frost damage of varying degrees may occur, resulting in losses such as reduced production, dead branches or dead trees.

[0004] Citrus fruits are even less resistant to frost. Sichuan and Chongqing are important late-maturing citrus production areas in my country, with an area of ​​more than 3 million mu of late-maturing citrus. Late-maturing citrus flowers in April, and the fruits are harvested from January to May of the following year. The fruits need to spend the winter on the trees. The lowest temperature in winter in the late-maturing citrus production areas of Sichuan and Chongqing is usually between -1℃ and 3℃. Although the lowest temperature is higher than the low temperature of -2℃ to -2.5℃ that citrus fruits can withstand, the late-maturing citrus fruits in low-lying areas are still frozen and rotten. For example, the late-maturing citrus production areas in Nanchong City, Sichuan and Changshou District, Chongqing have suffered fruit frost damage to varying degrees three times in the past five years (although the lowest temperature recorded by the meteorological station is 0~2℃). The late-maturing citrus fruits in low-lying areas have been frozen and rotten, with losses reaching 30%~80%, causing serious losses to production. Therefore, how to effectively reduce citrus frost damage has always been an important issue of concern to citrus scientific research and producers.

[0005] The existing citrus antifreeze methods mainly include smoke antifreeze, fire antifreeze, water spray antifreeze, crown covering antifreeze, and greenhouse protected cultivation antifreeze. Smoke antifreeze: A technical measure to prevent or reduce frost damage to citrus by burning materials to produce smoke to reduce the cooling of the ground and trees caused by long-wave radiation. Fire antifreeze: An agricultural technical measure to increase the local temperature of orchards or farmland by burning combustible materials to prevent crops from being damaged by frost. Water spray antifreeze: A technical measure to prevent or reduce frost damage to citrus by spraying water on citrus trees to release latent heat in water to slow down the temperature drop. Crown covering antifreeze: The principle of crown covering antifreeze is to cover the crown with a layer of insulation material, such as plastic film, shade net, straw mat, sack, etc., to reduce the direct contact between the crown and the cold air, thereby reducing the occurrence of frost damage. Greenhouse protected cultivation antifreeze: A technology that uses greenhouse facilities to protect crops and takes a series of measures to prevent crops from being damaged by low temperatures.

[0006] Chinese patent document CN111213533A discloses a method for protecting citrus in the northern edge of citrus planting areas from winter frost damage, comprising the following steps: 1) preliminary protection: planting windbreaks around the citrus orchard and cutting off late autumn shoots; 2) applying basal fertilizer: applying basal fertilizer to the citrus trees, digging arc-shaped or ring-shaped deep trenches along the crown of the tree when applying basal fertilizer, with a trench depth of 20-30 cm, applying fertilizer or spreading fertilizer on the ridge surface, and then cultivating the ridge surface by 20-30 cm; 3) winter garden cleaning: before the winter is about to come, cleaning the citrus trees and the surrounding areas, cleaning the surface and underground, cultivating or shallowly hoeing the entire orchard after the cleaning is completed, and whitening the main trunks and branches of the fruit trees with a whitening agent; 4) soiling before frost: cultivating each citrus tree before frost comes. Soil, the height of the soil is 15-30cm. After the low temperature, the soil above the root neck should be dug up in time to prevent root rot and damage by diseases and insects; 5) Covering grass and wrapping trees: Cover the rows in the orchard with straw, weeds, and leaves, and wrap the trunk and main branches of the citrus tree tightly with straw. Before and after the frost, cover the tree crown with a four-needle or six-needle shade net; 6) Irrigation before freezing: 7-10 days before freezing, irrigate the citrus trees to store heat with water, reduce the temperature difference, keep the ground temperature relatively stable during the cold and freezing period, and reduce frost damage; 7) Fumigation to prevent frost: When a cold wave comes, ignite the fuel to let the smoke cover the entire garden. The fuel is composed of sawdust, weeds and soil; 8) Clear snow: After snowfall, remove the accumulated frost and snow on the branches of the fruit trees to avoid breaking the branches and causing frost damage.

[0007] The existing technology has the following shortcomings: the lowest winter temperature in late-ripening citrus production areas is usually between -1°C and 3°C. Although the lowest temperature is higher than the -2°C to -2.5°C low temperature that citrus fruits can withstand, late-ripening citrus fruits in low-lying areas are still subject to frostbite and frostbite. The cost of the insulation materials and construction materials for the existing antifreeze methods, such as canopy covering for antifreeze and greenhouse protection for antifreeze, is high and inconvenient to operate, and also reduces light; smoke antifreeze and fire antifreeze require lighting many fires in the cold early morning, which will produce harmful gases and pollute the environment; smoke antifreeze, fire antifreeze and water antifreeze all require the purchase of materials and equipment, which is costly and difficult to promote in production. Summary of the invention

[0008] The present invention provides a method for reducing citrus frost damage by fermenting pruned branches to generate heat with low cost, no pollution and good antifreeze effect, which is characterized by comprising the following steps: Step 1, mixing citrus branches and leaves, cow dung, rapeseed cake, nitrogen fertilizer, phosphorus fertilizer and compost fermentation agent evenly to prepare a fermentation mixture; Step 2: The fermented mixture is made into a fermentation heat generating pile in the orchard.

[0009] Preferably, the citrus branches and leaves are selected from citrus branches and leaves pruned in autumn and winter.

[0010] In order to fully ferment and raise the temperature, the citrus branches and leaves are crushed into a size of 1-3 cm.

[0011] In the present invention, the mass percentages of the citrus branches and leaves, cow dung, rapeseed cake, nitrogen fertilizer, phosphorus fertilizer and compost fermentation agent are 75wt%-83wt%, 9wt%-15wt%, 3wt%-5wt%, 0.5wt%-0.9wt%, 3wt%-4wt% and 0.05wt%-0.1wt%. The preferred mass percentages are 80wt%, 12wt%, 4wt%, 0.7wt%, 3.22wt% and 0.08wt%.

[0012] In order to fully ferment and increase the temperature, the cow dung is selected to be semi-dry cow dung with a water content of 40%-50%.

[0013] Preferably, the moisture content of the rapeseed cake is not higher than 20%; the phosphate fertilizer is calcium magnesium phosphate fertilizer, and the effective phosphorus content is not less than 12%; the nitrogen fertilizer is urea, and the nitrogen content is not less than 45%.

[0014] Preferably, the composting fermentation agent is EM bacteria composting fermentation agent, and the effective live bacteria count is not less than 200 million / gram.

[0015] Preferably, in step 1.1, citrus branches and leaves, cow dung, rapeseed cake, phosphate fertilizer and compost fermentation agent are mixed evenly in proportion; Step 1.2: dilute the nitrogen fertilizer with water to a 1% to 2% aqueous solution, spray it evenly on the mixture in step 1.1, and mix it evenly to prepare a fermentation mixture.

[0016] In order to accurately respond to freezing weather and reduce or prevent freezing losses, step 2.1, 25 to 50 days before the freezing weather of citrus fruits arrives, the fermentation mixture is made into a fermentation heat generating pile and placed under the citrus trees in the low-lying part of the orchard; Step 2.2: Cover the fermentation heat pile with a film to keep moisture and heat in the early stage. When the temperature inside the pile rises to above 50°C, remove the film. Turn the pile for ventilation 2 to 4 days before low temperature and frost damage occurs in the orchard.

[0017] In order to ensure that the rising temperature is sufficient, 5-8 fermentation heat generating piles are evenly distributed per acre of citrus orchard. The bottom diameter of each fermentation heat generating pile is 1.2-1.8 meters and the height is 1-1.5 meters.

[0018] The present invention has the following beneficial effects: 1. When the temperature drops to -2°C to -2.5°C, citrus fruits may be damaged by freezing. The lowest winter temperature in the late-ripening citrus production areas of Sichuan and Chongqing is usually between -1°C and 3°C. However, due to the sinking and gathering of cold air in the low-lying areas of the orchard, the lowest temperature is lower than the temperature recorded by the weather station (the temperature at the weather station is the temperature in the lawn louvered box), usually 3 to 6°C lower (depending on the terrain and wind force). When encountering a large cold wave, low temperatures of -2°C to -5°C often occur in the low-lying areas of the citrus orchard, causing the fruits to freeze. The present invention increases the crown temperature of citrus trees in low-lying areas in winter by 2 to 3°C, so that the temperature in the low-lying areas of the citrus orchard is higher than the freezing low temperature of -2°C, thereby alleviating or preventing citrus frostbite, preventing the fruit from losing its commercial value or falling off in large quantities due to frostbite or rottenness caused by low temperature, reducing or preventing frostbite losses, ensuring the stable yield of citrus trees, and reducing yield fluctuations caused by frostbite.

[0019] 2. In the present invention, citrus branches and leaves account for the largest proportion, and the cost is only the expense of manual transportation and crushing. The pruned citrus branches and leaves are turned into treasures. Only a small amount of cow dung, rapeseed cake, nitrogen fertilizer, phosphorus fertilizer and compost fermentation agent are needed. The preparation cost is low, which is much lower than the cost investment of building materials, insulation materials and equipment purchase required in the existing antifreeze methods; and in the early spring, all materials of the fermentation heat generating pile in the present invention can be used for fertilizing the orchard and improving the soil; furthermore, the present invention will not affect the light intensity or produce harmful gases, is safe and harmless, and is easy to use, which is conducive to its promotion and application.

[0020] 3. The present invention reduces or prevents frost damage to citrus fruits without adversely affecting other properties.

[0021] 4. It is not restricted by terrain, has strong operability, and is suitable for composting, fermentation and heating in various terrains. DETAILED DESCRIPTION

[0023] The following is further described in detail through specific implementation methods: Those skilled in the art know that citrus frost damage refers to damage to citrus caused by ice forming between cells or inside cells when the temperature drops below freezing. When the temperature drops to -2°C to -2.5°C or below, citrus fruits may suffer frost damage.

[0024] Crown: refers to the part above the trunk of a tree or semi-tree, including main branches, side branches, fruiting branches, new shoots and attached leaves.

[0025] wt%: It is the abbreviation of mass percentage, which indicates the mass percentage of a substance in a mixture.

[0026] ZDR-20 automatic temperature and humidity recorder: an instrument that can automatically record temperature and humidity with an accuracy of 0.1°C. It can be set to record temperature and humidity every few minutes as needed.

[0027] Rapeseed cake: The powdery or flaky residue left after rapeseed is mechanically squeezed for oil.

[0028] EM bacteria composting fermentation agent is a composting fermentation agent purchased online with an effective live bacteria count of not less than 200 million / gram.

[0029] Nitrogen fertilizer: a unit fertilizer with nitrogen (N) as the main component and a specified amount of N, which can provide nitrogen nutrition to plants when applied to the soil. In the present invention, urea is preferred.

[0030] Urea: Also known as carbamide, carbonamide, the chemical formula is CH4N2O or CO(NH2)2. It is a white crystal, tasteless and odorless, easily soluble in water, ethanol and benzene, slightly soluble in ether and chloroform. Urea is one of the simplest high-nitrogen organic compounds, the main nitrogen-containing end product of protein metabolism and decomposition in mammals and some fish, and can be used as fertilizer, animal feed, explosives, glue stabilizer and chemical raw materials.

[0031] Phosphate fertilizer: Phosphate fertilizer is a fertilizer containing phosphorus, a nutrient element for crops, produced from phosphate rock. Phosphorus is a component of plant cell protoplasm and plays an important role in cell growth and proliferation. The present invention uses agricultural phosphate fertilizer, which can be natural phosphate fertilizer: sea guano or animal bone meal and fish bone meal; chemical phosphate fertilizer: calcium magnesium phosphate fertilizer, superphosphate, monoammonium phosphate and other agricultural phosphate fertilizers.

[0032] Calcium magnesium phosphate fertilizer: an agricultural fertilizer produced from phosphate rock and magnesium silicate minerals.

[0033] Fermentation heat pile: microorganisms use organic matter to carry out life activities under suitable conditions to generate heat and metabolites; organic matter (such as plant branches and leaves, crop straw, livestock and poultry manure, etc.) is piled together to form a fermentation pile. In this process, it is necessary to ensure that the moisture content, ventilation and temperature of the fermentation pile are suitable for the growth and reproduction of microorganisms.

[0034] Compost starter: Compost starter is a microbial preparation used to accelerate the decomposition and maturity of organic matter. It usually contains a variety of beneficial microorganisms, such as bacteria and fungi, which can decompose organic matter and convert it into stable, nutrient-rich compost.

[0035] Those skilled in the art know that frostbite on citrus fruits manifests itself in that the color of the epidermis of fruits that have suffered slight frostbite is significantly different from other parts, with the epidermis being darker in color and appearing water-soaked brown. When the ambient temperature is too low, the inside of the fruit will also be damaged by frostbite, with ice accumulating in the flesh. When the ice in severely frostbitten fruits melts, the flesh also melts into a semi-liquid state, and then dries up to form hollows or cotton-like shapes.

[0036] Water-soaked spots: Water-soaked, moist, discolored spots or patches that appear on the surface of fruits or leaves.

[0037] A method for reducing citrus frost damage by fermenting and heating pruned branches, comprising the following steps: Step 1, mixing citrus branches and leaves, cow dung, rapeseed cake, nitrogen fertilizer, phosphorus fertilizer and compost fermentation agent evenly to prepare a fermentation mixture; Step 2: The fermented mixture is made into a fermentation heat generating pile in the orchard.

[0038] In the present invention, the mass percentages of the citrus branches and leaves, cow dung, rapeseed cake, nitrogen fertilizer, phosphorus fertilizer and compost fermentation agent are in the range of 75wt% to 83wt%, 9wt% to 15wt%, 3wt% to 5wt%, 0.5wt% to 0.9wt%, 3wt% to 4wt% and 0.05wt% to 0.1wt%. The preferred mass percentages are 80wt%, 12wt%, 4wt%, 0.7wt%, 3.22wt% and 0.08wt%.

[0039] In the present invention, 5-8 fermentation heat generating piles are evenly distributed per acre of citrus orchard, preferably 6 or 7; each fermentation heat generating pile has a bottom diameter of 1.2-1.8 meters and a height of 1-1.5 meters, preferably a bottom diameter of 1.5 meters and a height of 1.2 meters or a bottom diameter of 1.5 meters and a height of 1.3 meters.

[0040] Example 1 A method for reducing citrus frost damage by fermenting and heating pruned branches, comprising the following steps: Step 1: Add 3.4 tons of citrus branches and leaves that have been pruned in November and crushed to about 1 cm, 0.4 tons of cow dung, 0.12 tons of rapeseed cake, 0.16 tons of calcium magnesium phosphate fertilizer, and 4 kg of EM bacteria compost fermentation agent in sequence, and mix evenly with a turning machine to form a fermentation mixture.

[0041] Step 2, dilute 0.036 tons of urea with water to form a 2% urea aqueous solution, spray it evenly into the fermentation mixture, and mix it evenly to form a fermentation mixture; Step 3, 43 days before the onset of citrus frost damage weather, making the fermentation mixture into a fermentation heat generating pile and placing it under the citrus trees in the low-lying part of the orchard; Step 4: Cover the fermentation heat pile with a film to keep moisture and heat in the early stage. When the temperature inside the pile rises to above 50°C, remove the film. Turn the pile over for ventilation 3 days before low temperature and frost damage occurs in the orchard.

[0042] The water content of the cow dung after mechanical dehydration is 40%.

[0043] The rapeseed cake is the powdered rapeseed residue after mechanical oil pressing, and has a water content of 10%.

[0044] The nitrogen content of the urea is 46%.

[0045] The effective phosphorus content of the calcium magnesium phosphate fertilizer is 12%.

[0046] The EM bacteria composting fermentation agent is an EM bacteria composting fermentation fertilizer fermentation agent with an effective live bacteria count of 200 million / gram purchased online. 2022-23 Trial on Reducing Freeze Damage to Citrus Fruit The orchard in question is the citrus orchard of Chongqing Guilai Fruit Industry Co., Ltd. in Maliu Village, Xianfeng Town, Jiangjin District, Chongqing. The orchard is a late-maturing hybrid citrus planted in March 2016, the rootstocks used are Carrizo orange rootstock and Tarocco blood orange interstock, and are cultivated and managed in a conventional manner. The orchard has a shallow hilly terrain, and there are two low-lying areas in the orchard's Wogan planting area, named "Dagou" and "Laoyingou". The Wogan fruits at the lowest point of these two low-lying areas have suffered varying degrees of frost damage in most years.

[0048] Treatment area: On December 1, 2022, the fermentation mixture prepared in Example 1 was made into 8 fermentation heat generating piles, which were evenly piled under the citrus trees in the lowest depression of the "big ditch". The lowest depression area was about 1.2 acres. The bottom diameter of each fermentation heat generating pile was 1.4 meters to 1.5 meters and the height was 1.1 meters to 1.2 meters. The surface of the fermentation heat generating pile was covered with a film for heat preservation and moisture retention. On January 6, 2023, when the temperature inside the fermentation heat generating pile rose to 50°C, the film was removed. According to the weather forecast, there will be a low temperature cold wave on January 14, 2023, so a pile turning and ventilation was carried out on January 11.

[0049] Control area: The control area is the "old ditch", which is a low-lying area of ​​about 1.5 acres. There is no fermentation heat pile under the Wogan trees.

[0050] ZDR-20 automatic temperature and humidity recorders were hung on the citrus trees in the treatment area and the control area. The hanging position was in the middle of the crown of each tree. Three ZDR-20 automatic temperature and humidity recorders were hung in each of the treatment area and the control area, and the temperature changes were automatically recorded every 30 minutes.

[0051] A cold wave arrived on January 14, 2023, and the temperature dropped significantly from January 14 to 19. The lowest temperature recorded by the Jiangjin District Meteorological Station was 0~2℃, and the lowest temperature recorded in the experimental orchard is shown in Table 1.

[0052] Table 1 Comparison of the lowest temperatures in the experiment of reducing frost damage of citrus by fermentation heat generated by pruned branches from January 14 to 19, 2023 (℃) 14th 15th 16th 17th 18th 19th Crown temperature in fermentation heat treatment area (℃) 2.3 0.8 -0.5 0.0 0.4 3.7 Crown temperature in control area (℃) -0.5 -1.5 -3.2 -3.0 -2.5 1.7 Temperature difference (℃) 2.8 2.3 2.7 3.0 2.9 2.0 From the results in Table 1, it can be seen that the fermentation heat pile of pruned branches piled under the citrus tree canopy increased the minimum temperature of the citrus tree canopy by 2.0~3.0℃ during the low-temperature cold wave period, when the cold air that is prone to frost damage gathered in the low-lying areas of the orchard. Because the lowest temperature in the orchard occurs in the early morning, the temperature is lowest in the low-lying areas of the orchard in the windless early morning, resulting in frost damage to the fruits on the citrus trees in the low-lying areas. The fermentation heat pile of pruned branches piled under the tree can effectively increase the canopy temperature. When the lowest temperature occurred from January 14 to 19, the lowest canopy temperature in the treatment area was 0℃~-0.5℃ (the frost damage temperature of citrus fruits is -2℃ and below), avoiding frost damage to the fruits. No frozen fruits were found in the field, and all fruits were normal; while the lowest canopy temperature of the control during this period was -3.0℃, and the fruits were frost damaged, about 2 / 3 of the fruits were frostbitten, and frostbite spots appeared on the fruit surface, which then became infected and fell off.

[0053] When applying spring fertilizer in March 2023, all materials from the fermented heat pile will be used to fertilize the orchard, improve the soil, and further reduce production costs.

[0054] Example 2 A method for reducing citrus frost damage by fermenting and heating pruned branches, comprising the following steps: Step 1: Add 3.1 tons of citrus branches and leaves pruned in November and crushed to about 3 cm, 0.6 tons of cow dung, 0.15 tons of rapeseed cake, 0.12 tons of calcium magnesium phosphate fertilizer, and 2 kg of EM bacteria compost fermentation agent in sequence, and mix evenly with a turning machine to form a fermentation mixture.

[0055] Step 2, dilute 0.02 tons of urea with water to make a 1% urea aqueous solution, spray it evenly into the fermentation mixture, and mix it evenly to make a fermentation mixture; Step 3, 47 days before the onset of citrus frost damage weather, making the fermentation mixture into a fermentation heat generating pile and placing it under the citrus trees in the low-lying part of the orchard; Step 4: Cover the fermentation heat pile with a film to keep moisture and heat in the early stage. When the temperature inside the pile rises to above 50°C, remove the film. Turn the pile over and ventilate it 4 days before low temperature and frost damage occurs in the orchard.

[0056] The water content of the cow dung after mechanical dehydration is 50%.

[0057] The rapeseed cake is the powdered rapeseed residue after mechanical oil pressing, and has a water content of 20%.

[0058] The nitrogen content of the urea is 46%.

[0059] The effective phosphorus content of the calcium magnesium phosphate fertilizer is 16%.

[0060] The EM bacteria composting fermentation agent is an EM bacteria composting fermentation agent purchased online with an effective live bacteria count of 400 million / gram. 2023-24 Trial to Reduce Freeze Damage to Citrus Fruit The orchard in question is the citrus orchard of Chongqing Guilai Fruit Industry Co., Ltd. in Maliu Village, Xianfeng Town, Jiangjin District, Chongqing. The orchard is a late-maturing hybrid citrus planted in March 2016, the rootstocks used are Carrizo trifoliate orange rootstock and Tarocco blood orange interstock, and are cultivated and managed in a conventional manner. The orchard has a shallow hilly terrain, and there are two low-lying areas in the distribution area of ​​​​the Wogan, named "Dagou" and "Laoyingou". The Wogan fruits at the lowest point of these two low-lying areas have suffered varying degrees of frost damage in most years.

[0062] To further verify the experimental results, the treatment and control areas will be swapped in 2023-24.

[0063] Treatment area: On December 5, 2023, the fermentation mixture prepared in Example 2 was made into 8 fermentation heat generating piles, which were evenly piled under the citrus trees in the lowest depression of the "old ditch". The lowest depression area is about 1.5 acres. The bottom diameter of each fermentation heat generating pile is 1.4 meters to 1.5 meters, and the height is 1.1 meters to 1.2 meters. The surface of the fermentation heat generating pile is covered with a film for heat preservation and moisture retention. On January 12, 2024, when the temperature inside the fermentation heat generating pile rises to 50°C, the film is removed. According to the weather forecast, there will be a low temperature cold wave on January 22, 2024, so a pile turning and ventilation will be carried out on January 18.

[0064] Control area: The control area is "Dagou", where there is no fermentation heat-generating pile under the Wogan trees in this low-lying area.

[0065] ZDR-20 automatic temperature and humidity recorders were hung on the citrus trees in the treatment area and the control area. The hanging position was in the middle of the crown of each tree. Three ZDR-20 automatic temperature and humidity recorders were hung in each of the treatment area and the control area, and the temperature changes were set to be automatically recorded every 30 minutes.

[0066] A cold wave arrived on January 22, 2024, and low temperatures continued from January 22 to 26. The lowest temperature recorded by the Jiangjin District Meteorological Station was 3~4℃, and the lowest temperature recorded in the experimental orchard is shown in Table 2.

[0067] Table 2 Comparison of the lowest temperatures in the experiment of reducing frost damage of citrus by fermentation heat generated by pruned branches from January 22 to 26, 2024 (℃) 22nd 23rd 24th 25th 26th 27th Crown temperature in fermentation heat treatment area (℃) 1.1 2.4 0.2 1.3 4.2 6.6 Crown temperature in control area (℃) -1.7 0.3 -2.7 -1.8 1.5 4.4 Temperature difference (℃) 2.8 2.1 2.9 3.1 2.7 2.2 From the results in Table 2, it can be seen that the crown temperature in the treatment area was higher than that in the control area when the experimental positions of the treatment area and the control area in 2023-24 were swapped with those in 2022-23. During the low-temperature cold wave, the minimum crown temperature of citrus trees in the low-lying areas where cold air gathered in the treatment area increased by 2.1~3.1℃. On January 24, the lowest crown temperature in the treatment area was 0.2℃, which did not reach the freezing temperature of citrus fruits. The fruits were normal and no fruits were found to be frozen; on January 24, the lowest crown temperature in the control area was -2.7℃, which was lower than the freezing temperature of fruits (-2℃). The fruits had slight freezing damage, and the fruit surface of the fruits outside the crown had water-soaked spots of freezing damage.

[0068] When applying spring fertilizer in March 2024, all materials from the fermented heat pile will be used to fertilize the orchard, improve the soil, and further reduce production costs.

[0069] The above is only an embodiment of the present invention. The common sense such as the known specific structure and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field know all the common technical knowledge in the technical field of the invention before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for ordinary technicians in the relevant field to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent. The protection scope required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for reducing citrus frost damage by fermenting pruned branches to generate heat, characterized in that: The following steps are involved: Step 1, mixing citrus branches and leaves, cow dung, rapeseed cake, nitrogen fertilizer, phosphorus fertilizer and compost fermentation agent evenly to prepare a fermentation mixture; Step 2: The fermented mixture is made into a fermentation heat generating pile in the orchard.

2. The method for reducing citrus frost damage by fermenting pruned branches to generate heat according to claim 1, characterized in that: The citrus branches and leaves are selected from citrus branches and leaves pruned in autumn and winter.

3. The method for reducing citrus frost damage by fermenting pruned branches to generate heat according to claim 2, characterized in that: The citrus branches and leaves are crushed to a size of 1-3 cm.

4. The method for reducing citrus frost damage by fermenting and heating pruned branches according to any one of claims 1 to 3, characterized in that: The mass percentages of the citrus branches and leaves, cow dung, rapeseed cake, nitrogen fertilizer, phosphorus fertilizer and compost fermentation agent are 75wt%~83wt%, 9wt%~15wt%, 3wt%~5wt%, 0.5wt%~0.9wt%, 3wt%~4wt% and 0.05wt%~0.1wt%.

5. The method for reducing citrus frost damage by fermenting pruned branches to generate heat according to claim 4, characterized in that: The cow dung is semi-dry cow dung with a water content of 40%-50%.

6. The method for reducing citrus frost damage by fermenting pruned branches to generate heat according to claim 5, characterized in that: The moisture content of the rapeseed cake is not higher than 20%; the effective phosphorus content of the phosphate fertilizer is not lower than 12%; and the nitrogen content of the nitrogen fertilizer is not lower than 45%.

7. The method for reducing citrus frost damage by fermenting pruned branches to generate heat according to claim 6, characterized in that: The composting fermentation agent adopts EM bacteria composting fermentation agent, and the effective live bacteria count is not less than 200 million / gram.

8. The method for reducing citrus frost damage by fermenting pruned branches to generate heat according to claim 7, characterized in that: Step 1.1, mix citrus branches and leaves, cow dung, rapeseed cake, phosphate fertilizer and compost fermentation agent in proportion; Step 1.2: dilute the nitrogen fertilizer with water to a 1% to 2% aqueous solution, spray it evenly on the mixture in step 1.1, and stir evenly to prepare a fermentation mixture.

9. The method for reducing citrus frost damage by fermenting and heating pruned branches according to any one of claims 5 to 8, characterized in that: The following steps are involved: Step 2.1, 25 to 50 days before the onset of citrus frost damage weather, making the fermentation mixture into a fermentation heat generating pile and placing it under the citrus trees in the low-lying part of the orchard; Step 2.2: Cover the fermentation heat pile with a film to keep moisture and heat in the early stage. When the temperature inside the pile rises to above 50°C, remove the film. Turn the pile for ventilation 2 to 4 days before low temperature and frost damage occurs in the orchard.

10. The method for reducing citrus frost damage by fermenting pruned branches to generate heat according to claim 9, characterized in that: There are 5-8 fermentation heat generating piles evenly distributed on every acre of citrus orchard. The bottom diameter of each fermentation heat generating pile is 1.2-1.8 meters and the height is 1-1.5 meters.