Fruit sunburn prevention agent and fruit sunburn prevention method

Abstract

To provide: a fruit sunburn prevention agent that can be used easily and can effectively prevent a fruit from being sunburned by being firmly attached to a surface of the fruit; and a fruit sunburn prevention method using the fruit sunburn prevention agent.SOLUTION: A fruit sunburn prevention agent includes an aqueous slurry containing fine particles of hydrated lime and water. The fine particles of hydrated lime are fine particles having an average particle diameter (D50)) of 0.1-1.0 μm, in which a proportion of particles of 5.0 μm or more is 4.0 mass% or less. The aqueous slurry contains 2.0 mass% or more of the fine particles of hydrated lime. A fruit sunburn prevention method uses the fruit sunburn prevention agent.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a sunburn preventive agent and a sunburn prevention method for preventing sunburn of citrus fruits and the like.

Background Art

[0002] Due to the high temperature in summer and strong sunlight caused by global warming, fruits are sunburned, and the problem is that the commercial value decreases. In particular, in recent years, the demand for high-quality premium fruits has been high, and sunburn is a serious problem in such premium fruits. In fact, this problem has been prominently addressed in citrus fruits.

[0003] As a means to solve such problems, conventionally, for example, a sunburn preventive agent for citrus fruits containing fine powder silica and its spreading agent as essential components has been proposed (see Patent Document 1). In recent years, micronized calcium carbonate hydrating agent has been actually used as a sunburn preventive agent for citrus fruits, and certain effects have been obtained (see Non-Patent Document 1). This micronized calcium carbonate hydrating agent is sprayed on the fruits of fruit trees by hand using a sprayer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Non-Patent Documents

[0005]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Although the micronized calcium carbonate hydrate has a certain sunburn prevention effect as described above, the calcium carbonate fine particles are powders with a size in the range of several μm to several tens of μm, and have poor dispersibility in liquid. When a spraying solution is prepared with a sprayer, it will settle if left standing for a long time, and it is necessary to stir again, etc., so there is a problem that smooth work cannot be performed. There is also a problem that the aggregated calcium carbonate fine particles clog the hoses and nozzles of the sprayer. Furthermore, the sunburn preventer mainly composed of calcium carbonate has a weak binding force when dried and is likely to peel off from the fruit surface, and is also likely to peel off from the fruit surface even by heavy rain or typhoon.

[0007] An object of the present invention is to provide a sunburn preventer for fruits that can be easily used and firmly adheres to the fruit surface to effectively protect the fruit from sunburn, and a method for preventing sunburn of fruits using the same.

Means for Solving the Problems

[0008] In recent years, unmanned aerial vehicles called drones have come to be used in many fields, and it is expected that drones will also be used for spraying sunburn preventers. However, although the particle size of the sunburn preventer containing the above calcium carbonate fine particles is not small enough, there are problems such as particle sedimentation and clogging at various parts of the sprayer equipped on the drone. In addition, since the drone cannot secure a large amount of power due to power supply by battery and high injection force cannot be expected, it is difficult to spray a solvent containing large particles. There is also a problem that the above clogging problem is promoted, and it is practically difficult to apply to drones.

[0009] Under such circumstances, the inventor focused on a slurry of very fine slaked lime (calcium hydroxide) particles. Since calcium hydroxide is highly alkaline, there is a concern about human spraying, but there is no such concern with spraying by an unmanned aircraft. Also, by using very fine slaked lime particles, it was found that problems such as particle sedimentation, clogging, and injection ability in the sprayer equipped on the unmanned aircraft can be solved. In addition, due to its characteristics, slaked lime has good adhesion to fruits and is excellent in film formation on the fruit surface during drying, so it has durability and can effectively prevent sunburn of fruits. The present invention was thus completed.

[0010] That is, the present invention is as follows. [1] An aqueous slurry containing slaked lime fine particles and water, wherein the slaked lime fine particles are fine particles having an average particle diameter (D50) of 0.1 to 1.0 μm and a proportion of particles of 5.0 μm or more of 4.0% by mass or less, and are contained in the aqueous slurry at a proportion of 2.0% by mass or more and which is characterized as a sunburn preventive agent for fruits.

[0011] [2] The sunburn preventive agent for fruits according to [1] above, further characterized by containing a spreading agent. [3] The sunburn preventive agent for fruits according to [1] or [2] above, characterized in that calcium carbonate particles having an average particle diameter (D50) of 1.0 to 5.0 μm are contained at a proportion of 5.0% by mass or less. [4] The sunburn preventive agent for fruits according to any one of [1] to [3] above, characterized in that it is for preventing sunburn of citrus fruits.

[0012] [5] A method for preventing sunburn of fruits, characterized by spraying the sunburn preventive agent for fruits according to any one of [1] to [4] above onto the fruits of fruit trees using an unmanned aircraft. [6] A cultivation method for fruits with sunburn prevented, characterized by spraying the sunburn preventive agent for fruits according to any one of [1] to [4] above onto the fruits of fruit trees using an unmanned aircraft.

Effects of the Invention

[0013] The fruit sunburn inhibitor and the fruit sunburn prevention method of the present invention can be easily used and can effectively protect fruits from sunburn.

Embodiments for Carrying Out the Invention

[0014] The fruit sunburn inhibitor of the present invention is an aqueous slurry containing slaked lime fine particles and water. The slaked lime fine particles are fine particles with an average particle diameter (D50) of 0.1 to 1.0 μm and a proportion of particles of 5.0 μm or more of 4.0% by mass or less, and are contained in the aqueous slurry at a proportion of 2.0% by mass or more.

[0015] The fruit sunburn inhibitor of the present invention is an aqueous slurry containing slaked lime fine particles, which are very small particles, and water. It has high dispersibility and the particles do not settle even after being left standing for a long time. Therefore, when spraying on the fruits of fruit trees, there is no need for stirring during the operation, and clogging in a sprayer (including a nebulizer) can be prevented. Also, even a sprayer with low spraying ability equipped on an unmanned aircraft can spray (atomize) without problems.

[0016] Furthermore, the fruit sunburn inhibitor of the present invention has good adhesion to fruits and is excellent in film formation on the fruit surface during drying, so it has durability and can effectively prevent fruit sunburn. Also, since it shows relatively strong alkalinity, it can kill larvae and the like on the fruit surface.

[0017] The fruits targeted by the fruit sunburn inhibitor of the present invention are not particularly limited as long as they are fruits prone to sunburn problems, and citrus fruits such as mandarins, oranges, hassaku, grapefruits, and lemons can be preferably exemplified. Citrus fruits are roughly classified into the genera Citrus, Fortunella, and Poncirus. Also, fruits other than citrus fruits include apples, pears, persimmons, peaches, grapes, etc.

[0018] In the fruit sunburn inhibitor of the present invention, the average particle diameter (D50) of the slaked lime fine particles is 0.1 to 1.0 μm, preferably 0.1 to 0.8 μm, and more preferably 0.1 to 0.5 μm. By using fine particles in this range, excellent dispersibility can be ensured, and it can be used without problems even when using a sprayer with low spraying ability equipped on an unmanned aircraft.

[0019] The average particle diameter (D50) means the particle diameter at the point where it becomes 50% in the cumulative volume distribution curve with the total volume of the particle size distribution determined on a volume basis being 100%, that is, the volume-based cumulative 50% diameter.

[0020] Moreover, the fruit sunburn inhibitor of the present invention preferably contains as few particles of 5.0 μm or more as possible, and in the fruit sunburn inhibitor of the present invention, the particles of 5.0 μm or more are 4.0 mass% or less. The content of particles of 5.0 μm or more is preferably 3.0 mass% or less.

[0021] The particle size distribution (particle content ratio) can be determined by a laser diffraction / scattering type particle size distribution measuring device (for example, LA-960 manufactured by Horiba, Ltd.).

[0022] The content ratio of the slaked lime fine particles in the fruit sunburn inhibitor of the present invention is 2.0 mass% or more, preferably 3.0 mass% or more, and preferably 5.0 mass% or more. By containing slaked lime fine particles in this amount range, fruit sunburn can be effectively prevented. The upper limit is not particularly limited, but is, for example, 20.0 mass%. Even if the content exceeds this, no improvement in the sunburn prevention effect is observed, and the cost becomes high.

[0023] The fruit sunburn inhibitor (aqueous slurry) of the present invention can be produced by mixing slaked lime fine particles and water. For example, it can be produced by the production method described in Japanese Patent No. 4606238.

[0024] In addition to the slaked lime fine particles, the fruit sunburn preventive agent of the present invention may contain other components. For example, it is preferable that the fruit sunburn preventive agent of the present invention contains a spreading agent. The surface of the fruit is in an environment where it is difficult to form a film by repelling water, but by containing a spreading agent, it becomes possible to more surely form a film on the fruit surface. The content ratio of the spreading agent is preferably 0.01 to 0.5% by mass, more preferably 0.01 to 0.2% by mass, and even more preferably 0.01 to 0.1% by mass.

[0025] As the spreading agent, polyoxyethylene nonylphenyl ether, polyoxyethylene resin acid ester, polyalkylene glycol alkyl ether, polyoxyethylene octylphenyl ether, sorbitan fatty acid ester, calcium lignin sulfonate, etc. can be used, and polyoxyethylene nonylphenyl ether is preferable.

[0026] Furthermore, the fruit sunburn preventive agent of the present invention may contain calcium carbonate particles having an average particle diameter (D50) of 1.0 to 5.0 μm in a proportion of 5.0% by mass or less. Thereby, cracking of the film formed by the fruit sunburn preventive agent can be suppressed, and sunburn can be prevented over a longer period. That is, when only slaked lime fine particles are present, since the particles are very small, cracks are likely to occur depending on the environment, but by containing calcium carbonate having relatively large particles, the occurrence of cracking can be suppressed. As the content of the calcium carbonate, 0.5 to 5.0% by mass is more preferable, and 1.0 to 3.0% by mass is even more preferable. The method for measuring the average particle diameter of the calcium carbonate particles is the same as the method for measuring the slaked lime fine particles described above.

[0027] The fruit sunburn preventive agent of the present invention can be sprayed with a sprayer having a high spraying ability for human spraying. However, as described above, it is preferably sprayed (atomized) with a sprayer equipped on an unmanned aircraft. By using an unmanned aircraft, the sunburn preventive agent can be more easily applied to the fruit. That is, in the present invention, it is preferable to spray the fruit sunburn preventive agent of the present invention onto the fruit of fruit trees using an unmanned aircraft to prevent sunburn and cultivate the fruit.

Examples

[0028] Examples and comparative examples are shown below, but the technical scope of the present invention is not limited thereto.

[0029] As the slaked lime fine particles, the fine particle slaked lime slurry "CalSetter" (manufactured by Tokuyama Corporation) was used. The average particle diameter (D50) was 0.29 μm or 0.41 μm, and the particles of 5.0 μm or more were 3% by mass or less. As the spreading agent, polyoxyethylene nonylphenyl ether was used. As the calcium carbonate, calcium carbonate A having an average particle diameter (D50) of 3.1 μm was used. Using these raw materials, the fruit sunburn preventive agents shown in Table 1 were manufactured.

[0030]

Table 1

[0031] During the latter half of June to the first ten days of August, corresponding to the fruit swelling period, it was sprayed twice onto the fruits of Satsuma mandarin fruit trees about 2 m in height using an unmanned aircraft. The spraying amount of the sunburn preventive agent was about 0.5 kg / tree. Table 2 shows the sunburn incidence rate of the Satsuma mandarin sprayed with the sunburn preventive agent.

[0032]

Table 2

[0033] As shown in Table 2, the incidence rate was lower than that of the non-sprayed Satsuma mandarin, and a significant difference was observed between the two.

Industrial Applicability

[0034] Since the fruit sunburn inhibitor and the fruit sunburn prevention method of the present invention are effective in preventing sunburn of citrus fruits and the like, they are industrially useful.

Claims

1. An aqueous slurry containing slaked lime fine particles and water, wherein the slaked lime fine particles are fine particles having an average particle diameter (D50) of 0.1 to 1.0 μm and a proportion of particles of 5.0 μm or more of 4.0% by mass or less, and are contained in the aqueous slurry at a proportion of 2.0% by mass or more Characterized by being a fruit sunburn preventive agent.

2. The fruit sunburn preventive agent according to claim 1, further comprising a spreading agent.

3. The fruit sunburn preventive agent according to claim 1, characterized in that calcium carbonate particles having an average particle diameter (D50) of 1.0 to 5.0 μm are contained at a proportion of 5.0% by mass or less.

4. The fruit sunburn preventive agent according to claim 1, characterized in that it is for preventing sunburn of citrus fruits.

5. A method for preventing fruit sunburn, characterized by spraying the fruit sunburn preventive agent according to any one of claims 1 to 4 onto the fruits of fruit trees using an unmanned aircraft.

6. A method for cultivating fruits with sunburn prevention, characterized by spraying the fruit sunburn preventive agent according to any one of claims 1 to 4 onto the fruits of fruit trees using an unmanned aircraft.

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