CN106982661B

CN106982661B - Flower and fruit thinning method for oranges

Info

Publication number: CN106982661B
Application number: CN201710243055.9A
Authority: CN
Inventors: 徐芳杰; 张学英; 李峰; 陈荣
Original assignee: Shanghai Academy of Agricultural Sciences
Current assignee: Shanghai Academy of Agricultural Sciences
Priority date: 2017-04-14
Filing date: 2017-04-14
Publication date: 2020-10-09
Anticipated expiration: 2037-04-14
Also published as: CN106982661A

Abstract

A flower and fruit thinning method for citrus comprises spraying flower thinning agent 1-2 days before full-bloom stage of citrus; and/or spraying a flower thinning agent within one week of the full-bloom period of the citrus; wherein the flower thinning agent is a calcium formate flower thinning agent, or a lime sulfur flower thinning agent, or an edible oil flower thinning agent, or a plant growth regulator flower thinning agent. The flower thinning and fruit thinning method does not damage tree bodies, saves time and labor, obviously improves fruit quality after high yield, increases the average single plant yield by more than 30 percent compared with the yield increased in the next year after spraying the flower thinning agent for 2 times, ensures that the fruit is uniform in size, the fruit surface is smooth and beautiful without black spots, the average soluble solid content (TSS) reaches 12 percent, and the whole profit of an orchard is stable.

Description

Flower and fruit thinning method for oranges

Technical Field

The invention belongs to the field of citrus cultivation, and particularly relates to a flower thinning and fruit thinning method for citrus.

Background

However, due to the fact that cultivation density is too high during initial planting, problems of crown closure, fruiting part outward movement, inner cavity void and the like generally occur in old orange gardens of thirty-four years old, and accordingly diseases such as excessive spindling due to poor ventilation and light transmission of the cause and effect garden and high diseases such as resinosis due to easy fruit surface scratching are caused.

On the other hand, due to shortage of agricultural labor population, extensive daily management of an orange garden, the fact that fruit growers hardly have the consciousness of appropriate flower thinning and fruit thinning to ensure quality and use of chemical fertilizers and organic fertilizers are not standardized, so that the phenomenon of 'big and small years' of oranges is serious, high yield of the oranges is achieved, but the purchase price is low, the temperature in northern regions is not enough in the average year, the fruit quality is poor under extensive management, the economic benefit is not high, the situation is more serious in recent years, even the situation is caused to cause the fruit growers to abandon oranges, breed rice or other crops, and the planting area of the oranges is greatly shrunk.

In order to enhance the tree vigor and improve the phenomenon of 'big and small years', in recent years, the cultivation mode of alternate fruiting every other year has been reported and tested on fruit trees such as apples, namely, fruit branches are removed by pruning or flowers and fruits are manually removed in leisure years, only shoots are taken out for cultivating trees, and the tree vigor is promoted to be rejuvenated; promoting shoot, cultivating fruiting branch group, promoting multiple fruiting and improving fruit quality in high-yield year; the two cultivation methods are alternately carried out, and the fruit bearing is realized every other year.

However, at present, the mechanization degree of the orchard is too low, and the mode of achieving tree leisure by cutting back and pruning is not only too long in time consumption for recovering the yield, but also large in labor consumption and difficult to accept by farmers, so that a yield control mode which is more convenient to operate, more suitable for advocating the current situation of the local orchard and more acceptable is required to be found.

The traditional chemical flower thinning agent is applied to apples and pears more generally, and different types of flower thinning agents have different action mechanisms, for example, chemical preparations such as lime sulfur, ferrous sulfate and the like mainly burn floral organs to reduce fruit setting, but in the actual application process, when the floral organs are burned, young leaves and twigs of new tips are easily burned, or the surfaces of fruits generate brown spots; calcium-containing compounds mainly burn stigmas and destroy pollination and fertilization, but salts such as calcium chloride and calcium nitrate are easy to damage growing points in use; spraying edible oil can form a layer of oil film on the stigma to prevent fertilization and reduce fruit setting, but if the concentration of the used oil is improperly set or the spraying time is not correct, the water bubbles appear on the leaves and the growth is blocked easily; some high molecular chemical preparations are also proved to have high-efficiency flower thinning effect, such as dinitrocresol, sulfate urea and the like, the action mechanism of the high molecular chemical preparations is to inhibit pollen tube germination so as to reduce fruit setting, but the high molecular chemical preparations cannot be widely popularized and used because most of the high molecular chemical preparations have adverse effects (such as heavy metal contained in the dinitrocresol) which are difficult to eliminate on the environmental ecology.

Growth regulators ethephon, ABA and the like are used for flower thinning and fruit thinning, and mainly promote the generation of cell abscission layers in the decomposition or metabolism process; NAA, BA and the like accelerate cell growth and division, and the effect on thinning fruits is more obvious. In addition, some insecticides such as carbaryl have been proved to have a remarkable thinning effect, but cannot be widely applied to production because they have damage to beneficial insects such as bees.

In recent years, a surfactant TMN-6 commonly used in chemical industry is used as a novel flower thinning agent, and the novel flower thinning agent also shows certain effect if being tried to be applied to stone fruit trees such as peaches, jujubes and the like. However, chemical thinning has a certain degree of association with the fruit tree variety characteristics, fruit characteristics, tree comprehensive conditions, weather conditions before and after application (including exact application time, current temperature and humidity, and the like) due to the variety of agent selection and the thinning effect, and a targeted flower thinning agent use recommendation model which can be used by different fruit tree varieties cannot be extracted.

Therefore, in most cases, manual and mechanical flower thinning which is time-consuming and labor-consuming is mainly performed on pear trees, fruits such as peaches and apricots are not suitable for fruit thinning by using methods of shaking trees and the like because fruits in the growing period are very hard and easy to break, and researches and reports on the influence of flower thinning and fruit thinning technology on the fruit quality and the application effect of chemical flower thinning and fruit thinning agents are very rare on oranges.

Disclosure of Invention

The invention aims to provide a flower and fruit thinning method for oranges, which does not damage tree bodies, saves time and labor, improves fruit quality after high yield, increases the average single-plant yield by more than 30 percent compared with that of the fruit produced in the same year after spraying a flower thinning agent twice, ensures that the fruit size is uniform, the fruit surface is smooth and beautiful without black spots, the average soluble solid content (TSS) reaches 12 percent, and the overall profit of an orchard is stable.

In order to achieve the purpose, the invention provides the following technical scheme:

a flower and fruit thinning method for citrus comprises the following steps:

1) spraying a flower thinning agent 1-2 days before the full-bloom period of the citrus; and/or

2) Spraying a flower thinning agent within one week of the citrus entering the full-bloom period;

wherein the flower thinning agent is a calcium formate flower thinning agent, or a lime sulfur flower thinning agent, or an edible oil flower thinning agent, or a plant growth regulator flower thinning agent.

Further, in the calcium formate flower thinning agent: the concentration of calcium formate is 10-25 mg/L, and the content of chitin is 0.5-2.5 wt% of the total amount of the flower thinning agent liquid medicine.

Preferably, the content of the effective components in the lime sulphur agent flower thinning agent is 1.8-3 g/L.

Further, the edible oil flower thinning agent contains 3-5% of edible oil by volume fraction and 0.5-2.5% of chitin or emulsifier by mass fraction.

The edible oil is selected from one or more of peanut oil, soybean oil and sunflower seed oil.

The flower thinning agent of the plant growth regulator comprises the following components: NAA aqueous solution with the concentration of 20-40 mg/L or ABA aqueous solution with the concentration of 250-600 mg/L.

Preferably, the flower thinning agent sprayed 1-2 days before the full-bloom stage is a calcium formate flower thinning agent or an edible oil flower thinning agent; the flower thinning agent sprayed in one week of the full-bloom stage is a plant growth regulator flower thinning agent.

When the flower and fruit thinning agent is prepared, the solvent can be water, and trace element fertilizers, pesticides and the like with different concentrations can be added according to actual operation requirements, such as foliar fertilization, pest control and the like, and the added trace elements or pesticides are used on the principle that the added trace elements or pesticides do not antagonize any active ingredients in the flower thinning agent.

The citrus belongs to self-fruiting, the flower thinning agent is sprayed to play a flower thinning role, the action mechanism of the flower thinning agent is specific to the flower organs, pollination and fertilization processes, the flower thinning agent is applied before the full-bloom stage, the flower thinning agent is sprayed 1-2 days before the full-bloom stage of the citrus, and the effect is good. The full-bloom period of the citrus is a period of full bloom of 25-50% of the total flower amount of the whole tree, and the total full-bloom period of the citrus in the year is usually 5-7 days.

The invention sprays the flower thinning agent in one week of the full-bloom stage, mainly cooperates with the application of the flower thinning agent before the full-bloom stage to play a role in strengthening the flower thinning effect, the reason is the same as other fruit trees, the full-bloom stage of citrus lasts only 5-7 d, the flower opening time of different parts of the whole tree is different, the flower thinning agent is sprayed in one week of the full-bloom stage, and the invention mainly aims at the flowers with a part of flowers which are late in blooming and/or the flowers which are not thinned after the first medicament treatment, the flowers form young fruits (embryonic forms) after pollination and fertilization, and the use of the flower thinning agent has two meanings: firstly, when the orchard only needs to control yield and does not need tree leisure (namely, the whole tree flower and fruit are erased as much as possible, and the yield is almost zero, so as to recover the tree vigor), spraying a flower thinning agent after the full-bloom period can avoid excessive thinning and excessive yield reduction; on the other hand, when alternate bearing techniques are required to be implemented in an orchard and the flowers and fruits of the whole trees are planned to be removed, a method of spraying the flower thinning agent once before and after the full-bloom period is generally adopted. In this case, spraying the flower thinning agent after the full-bloom stage serves as a supplementary means, which can achieve the effect of thinning flowers (fruits) for the second time, and further increase the amount of fallen flowers and fruits by thinning a part of late blossoming flowers and formed young fruits.

In the calcium formate flower thinning agent used in the invention, calcium formate can destroy viscosity of stigmas, injure ovaries and prevent fruits from developing, the calcium formate concentration is in a range of 10-25 mg/L, the flower thinning effect is good, the basic trend is that the higher the concentration is, the higher the flower thinning rate is, but when the concentration is too high, part of citrus has young and tender young shoots, and new leaves show phytotoxicity, such as: curling of growing points, shrinking of new leaves, browning of growing points, charring and the like, and therefore, the concentration of calcium formate cannot be increased at will in order to protect young shoots while successfully thinning flowers. In addition, calcium formate not only can reduce flower and control yield, but also has the effects of reducing fruit cracking and improving quality due to calcium content.

The chitin plays a role of an auxiliary agent in the flower thinning medicament, the chitin accounting for 0.5-5% of the total mass fraction of the liquid medicine is added into the liquid medicine, so that the chitin has better film forming property, the medicament can be more uniformly attached to the surfaces of flowers and fruits after spraying, the medicament effect is improved, the influence of rainfall on the flower thinning effect after application is reduced, the concentration is controlled during preparation, the viscosity of the finished product liquid medicine cannot be too high, and otherwise, a sprayer is easily blocked.

The edible oil flower thinning agent of the invention forms an oil film on the surface of the stigma, destroys the viscosity and the transferability of the stigma, influences the respiration of plants and causes fruit drop. Too high a concentration of edible oil may result in damage to young shoots, blistering of the surface of young leaves, etc., and a reduction or elimination of the symptoms of rain. The edible oil is nontoxic and harmless, can repair young shoots in time (symptoms can be relieved when the young shoots are slightly damaged) even if the concentration of the edible oil is slightly higher, and generally, the young shoots are not easily damaged when the concentration of the edible oil is less than 5%. When the edible oil flower thinning agent contains the emulsifier, the emulsifier mainly plays a role in increasing the relative stability of emulsion after the edible oil and the water are mixed, when the chitin is contained, the chitin plays a role similar to that in the calcium formate flower thinning agent, the film forming property of the liquid medicine is also increased, the medicine effect is improved, and the preparation is subject to the uniform mixing, proper viscosity and no layering of the liquid medicine.

The lime sulphur is a common orchard bactericide, is mainly used for clearing gardens after fruit harvesting in the past, plays a role in flower thinning by burning floral organs, particularly ovary parts when being used as a flower thinning agent, and can cause phytotoxicity to new leaves and young shoots when the using concentration is too high. If the using time is too late, the lime sulphur does not have obvious fruit thinning effect, but the surface of the fruit is easy to generate brown burnt plaques, the lime sulphur flower thinning agent for the citrus is 1.8-3 g/L of effective component, can be prepared from a lime sulphur solid dosage form with 45 wt% of the total effective component and water, can be purchased into a finished product in a farming shop, and can be prepared into 400 x 200-80 kg of liquid medicine by taking 200 times of liquid as an example, wherein the content of the effective component is 2.25 g/L.

In the flower thinning agent of the plant growth regulator, the action mechanism of ABA is mainly to promote cell abscission to generate flower and fruit abscission and the like; NAA is an auxin IAA analogue and can influence the metabolism of hormones in cells, inhibit fruit setting and promote the growth of new shoots, so that the plant growth regulator chemical is more suitable for thinning fruits and can be applied in the middle and later period after the full-bloom period begins. However, the flower thinning and fruit thinning effect of the NAA and the ABA is poor at low concentration, and even fruit setting is promoted, so that the higher concentration is set during flower thinning and fruit thinning, but the application concentration of the growth regulator as a flower thinning agent cannot be too high, and the young shoots can be curled, and the concentration of the ABA below 600mg/L and the concentration of the NAA below 40mg/L are considered as safer flower (fruit) thinning concentration.

The method is utilized to carry out flower thinning and yield control, not only can protect tree vigor and stabilize the nutrition level of trees, but also can improve fruit quality, and finally, the orchard is high in yield, stable in yield, high in quality and high in price, and benefits are improved. Even in a high-yield year, the tree is strong and strong, excessive flowers do not need to be left blindly to pursue high yield, the damage to the tree body is avoided, and the yield is controlled to be about 2500-3000 kg per mu generally and properly for middle-aged and old orchards.

Compared with the prior art, the invention has the following beneficial effects:

the invention utilizes the chemical flower thinning agent, does not damage the tree body, saves labor, has high efficiency, is far better than mechanical flower thinning, and is more easily accepted by farmers in theory than the medium and heavy truncation retraction updating technology because the tree body is not damaged in the alternate bearing technology.

Compared with the heavy pruning method, the chemical thinning method has faster yield recovery and less influence on comprehensive benefits. The heavy pruning method usually needs to take at least 2-3 years to recover the yield, and the yield control is needed after the pruning is carried out for the first time when the yield is high, otherwise, the excessive fruiting is good in fruit quality and high in yield, but the tree body is easily damaged again, the chemical thinning method can carry out the high yield fruiting the next year after the treatment, and the influence on the tree vigor is smaller.

The invention has specific requirements on the application time and concentration of the flower thinning agent, the comprehensive flower thinning rate exceeds 98 percent, the requirement of tree alternate leisure in alternate-year fruiting technology is basically met, and the flower thinning agent has no obvious influence on the growth vigor of trees, young leaves (growing points) of new shoots, fruit setting in the next year and quality.

Detailed Description

The present invention is further illustrated by the following specific examples.

Example 1 flower and fruit thinning method for controlling yield using citrus

The flower thinning agent is used for 1 time 1-2 days before the full-bloom period, the whole tree flower quantity is controlled in an old orange garden, and the purposes of controlling yield and improving quality are achieved, and the method specifically comprises the following steps:

1. overview of orchard

The tree age of the orchard is about 30 years, the crown width is about 4m multiplied by 3m, the original planting density is 3m multiplied by 3.5m, and the main diseases are resinopathy and anthracnose.

2. Method of administering a drug

The flower thinning agent listed in the table 1 is sprayed for 1 time 1-2 d before the full-bloom stage, the main branches and central flowers are avoided during spraying, the flower thinning agent is used as a control without treatment, natural fruit setting is carried out, and the flower thinning effect of various agents is observed within 30d after the treatment is finished.

3. Survey of comprehensive flower thinning rate

Selecting 3 big branches in different directions in the middle of a tree body to conduct listing investigation, firstly recording the total number of inflorescences before treatment, observing the developmental state of the inflorescences, deducing approximate flowering time, determining the first treatment time 1-2 days before most of the inflorescences on the central main branch enter the full-bloom stage, recording the flower falling amount for multiple times within 30 days after spraying, calculating the flower thinning rate, and the following steps are the same as the following steps, wherein the table 1 lists the effect comparison data of different types of flower thinning agents used before the full-bloom stage, wherein 5% of edible oil, 3% of chitin, 150 times of lime hydrate, 30mg/L of calcium formate and 3% of chitin are respectively used as comparison examples 1-3 of the flower thinning agents, and the comprehensive flower thinning rate is obtained by statistics after the first physiological fruit falling.

TABLE 1

As can be seen from table 1, 3% of edible oil + 1% of chitin (i.e. 1L of the liquid medicine contains 30ml of edible oil, and 1% of chitin is added at the same time), 200 times of lime sulfur mixture solution (400g of lime sulfur mixture crystal with a content of 45% is prepared into 400 × 200 ═ 80kg of liquid medicine, and the active ingredient is 2.25g/L), and 20mg/L of calcium formate + 1% of chitin are 3 kinds of medicaments with better comprehensive flower thinning effect, and the comprehensive flower thinning effect exceeds 97%, while the CK contrast flower drop rate is about 90%.

In the comparative example, the tender tips and young leaves are damaged due to the fact that the concentrations of the lime sulphur and the calcium formate are too high, and the young tips are damaged to different degrees by two treatments of 150 times of the lime sulphur (3 g/L of effective components) and 30mg/L of the calcium formate, including the fact that some drug spots appear on the surfaces of the tender leaves, the young tips are curled and scorched, and the like. When the chitin content is 3%, the liquid medicine is very viscous, so that a spray head is easy to block during spraying, and the film forming property is not good.

Example 2 yield control Using a method for thinning flowers and fruits of Citrus

The purpose is to investigate the effect of the plant growth regulator on flower and fruit thinning, and the rest is the same as example 1 except that the application method and the composition of the flower and fruit thinning agent are different.

The application method comprises the following steps: the plant growth regulator is used for 1 time in one week after full-bloom stage, the liquid medicine is covered by the whole tree, untreated control is adopted, and the condition of flower and fruit dropping is observed in 7 days after the treatment is finished.

Table 2 lists comparative data on the flower and fruit thinning effect of different types of growth regulators after full bloom, wherein the comprehensive flower (fruit) thinning rate was counted two weeks (14d) after spraying the flower thinning agent before physiological fruit dropping.

TABLE 2

As can be seen from Table 2, spraying growth regulators of different types and concentrations within one week after the full-bloom stage has certain flower and fruit thinning effects, but the effect difference among different trees is large, and the growth regulators usually promote flower and fruit dropping by influencing endogenous hormone metabolism, so the effect is slow.

Example 3 flower and fruit thinning method for controlling yield using citrus

The flower thinning agent is respectively used for 1 time about 1-2 days before the full-bloom period and 1 week after the full-bloom period, flowers and fruits of the whole tree are thinned out as much as possible, the purposes of leisure every other year and tree vigor recovery are achieved, the technology of moderate-gravity pruning and yield control and fruit thinning every other year is taken as a comparative example, and the method is specifically as follows:

1. overview of orchard

The tree age of the orchard is about 30 years, the crown width is about 4m multiplied by 3m, the original planting density is 3m multiplied by 3m, and the main diseases are resinophosis.

2. Method of administering a drug

The flower thinning agent listed in the table 3 is sprayed 1 time respectively 1-2 days before the full-bloom period and about 1 week after the full-bloom period, the whole tree is sprayed, untreated control is used as comparison, the tree is allowed to naturally bear fruits, the flower thinning effect of each agent is observed within 30 days after the treatment is finished, the comprehensive flower thinning effect data of the two-time agent treatment is listed in the table 3, 2-time TMN-612 mg/L spraying is used as comparison example, when the two-time flower thinning agent is sprayed, the calcium formate flower thinning agent or the edible oil flower thinning agent is sprayed 1-2 days before the full-bloom period, the plant growth regulator is sprayed within one week after the full-bloom period, and the comprehensive flower thinning rate is obtained by statistics after the first physiological fruit drop.

As can be seen from Table 3, the calcium formate, the edible oil and the lime sulphur have the effects of thinning flowers, the flowers fall obviously after the first treatment, but the lime sulphur can cause damage to young fruits after the full-bloom period, brown spots exist on the surfaces of the young fruits which are not thinned, the effects of growth regulators such as NAA and ABA, such as a flower thinning agent, are important in thinning fruits, the effects are obvious after the second treatment, and the thinning rate of the TMN-6 flower thinning agent is lower, which indicates that the flower (fruit) thinning effect of the agent on the citrus is poor.

Furthermore, NAA and ABA can be used before and after the full-bloom period, and the main action mechanism of the plant growth regulator is to influence the metabolism of endogenous hormones of plants, accelerate cell aging, generate 'abscission layer' and promote the shedding of flowers and fruits; the main action mechanism of the calcium formate and the edible oil is to destroy floral organs and prevent fruits from developing, so the using effect is better before the full-bloom period. The two types of agents can be matched according to actual field requirements (fruit retention amount, orchard tree vigor and the like).

4. Investigating the final result and the quality of the fruit

And (5) investigating the total number of inflorescences and fruits of each main branch after blossom at 20d, and calculating the fruit setting rate after treatment, wherein the investigation needs to be carried out once at 20d, 30d and 60d after treatment because the citrus has the problem of physiological fruit drop, and the last data is taken as the final fruit setting rate. After the fruit is ripe, taking the plant as a unit and picking the fruit from the whole tree, calculating the yield of the plant and the average single fruit weight, and measuring the basic indexes such as soluble solid content (TSS) and the like.

In table 4, data of average single plant yield and fruit quality after treatment by several flower thinning agents are listed, when the flower thinning agent is sprayed twice, the calcium formate flower thinning agent or the edible oil flower thinning agent is sprayed 1-2 days before the full-bloom stage, and the plant growth regulator is sprayed within one week after the full-bloom stage.

The method takes a heavy pruning forced leisure yield control mode as a comparative example, the plant yield, the average single fruit weight and the soluble solid content (TSS) are data of the 3 rd year after pruning, and compared with the yield control mode, the tree body is damaged again because the fruit bearing amount is large and the tree bearing time is too long after the fruit bearing amount is up to 12 months in the current year.

As can be seen from Table 4, after the fruits are properly thinned, the sizes of the fruits are more uniform, the surfaces of the fruits are smoother, oil cells are small and fine, the inner quality and flavor are more concentrated, and the quality improvement degree is not much different from that of a forced leisure method for heavily trimming tree bodies, wherein the comprehensive effect of 2 times of treatment of the calcium formate flower thinning agent and the NAA flower thinning agent is the best, the higher single plant yield is kept, the fruit flavor and quality are also better, compared with the annual data (CK) of average production, the yield increase amplitude is averagely over 30%, the average TSS of the pulp is up to 12% and is far higher than 9.5% of CK, and the purposes of controlling and improving the yield are achieved.

Technology for controlling yield through severe pruning and alternate year fruiting in comparative example

The method is characterized in that a mode of retracting and updating fruiting branch groups of high-age citrus trees in a medium-heavy section is adopted to control a part of citrus trees in a test area not to bear fruits in the current year, all extension branches of a tree body are basically completely cut off, only a first-stage main branch is reserved, meanwhile, organic fertilizer is applied again to cultivate fertility and promote new shoots, the height of a crown is reduced every other year, cluster-shaped fruiting branch groups at the middle lower part of the tree body are cultured heavily until the end of the next year, the part of leisure trees are all high in yield, the average single-plant yield is increased by more than 30% compared with the previous year, the fruit size is uniform, the fruit surface is smooth and attractive, no black spots exist, the average soluble solid content (TSS) reaches 12%, and the average TSS in the previous year. Although the effect is remarkable, the method takes a long time, and the normal yield can be recovered after the first pruning for more than three years.

Claims

1. A flower thinning and fruit thinning method for citrus comprises spraying a flower thinning agent 1-2 days before the full-bloom period of the citrus; or spraying the flower thinning agent once respectively 1-2 days before the full-bloom period of the citrus and within one week after the full-bloom period of the citrus; wherein the content of the first and second substances,

the flower thinning agent sprayed 1-2 days before the full-bloom stage is a calcium formate flower thinning agent, or a lime sulfur flower thinning agent, or an edible oil flower thinning agent;

the flower thinning agent sprayed in one week of the full-bloom stage is a plant growth regulator flower thinning agent, and the plant growth regulator flower thinning agent is an ABA (abscisic acid) aqueous solution with the concentration of 250-600 mg/L.

2. The method according to claim 1, wherein the calcium formate thinning agent comprises: the concentration of calcium formate is 10-25 mg/L, and the content of chitin is 0.5-2.5 wt% of the total amount of the flower thinning agent.

3. The method for thinning citrus fruit according to claim 1, wherein the content of active ingredients in the lime sulphur agent thinning agent is 1.8-3 g/L.

4. The method for thinning the flowers and the fruits of the citrus, according to claim 1, wherein the edible oil flower thinning agent comprises 3-5% by volume of edible oil and 0.5-2.5% by weight of emulsifier.

5. The method for thinning flowers and fruits of citrus according to claim 4, wherein the edible oil is selected from one or more of soybean oil, peanut oil and sunflower oil.

6. The method for thinning flowers and fruits of citrus according to claim 1, wherein the flower thinning agent sprayed 1-2 days before the full-bloom stage is a calcium formate flower thinning agent or an edible oil flower thinning agent.

7. A method of thinning citrus fruit according to any one of claims 1, 2, 3, 4 or 6 wherein the thinning agent further comprises a trace element fertilizer.

8. The method for thinning the flowers and the fruits of the citrus as claimed in claim 1 is used in the citrus yield control technology.