WO2024024851A1

WO2024024851A1 - Agent for suppressing decrease in yield amount

Info

Publication number: WO2024024851A1
Application number: PCT/JP2023/027425
Authority: WO
Inventors: 弘樹伊藤; 藤樹飯野
Original assignee: デンカ株式会社
Priority date: 2022-07-27
Filing date: 2023-07-26
Publication date: 2024-02-01

Abstract

One aspect of the present invention relates to an agent for suppressing decrease in a yield amount, the agent comprising a humic substance as an active ingredient. One aspect of the present invention relates to a method for culturing fruit vegetable crops or leaf vegetable crops under a condition under which a chemical fertilizer application amount is lower than a conventional fertilizer application amount.

Description

Yield reduction inhibitor

The present invention relates to a yield reduction inhibitor.

In agricultural fields around the world, cultivated land has some kind of poor soil environment such as pH, dryness, or moisture damage, and the reduction in crop yields due to poor nutrition is one of the problems that must be solved as the world's population increases. It is. Additionally, in March 2021, the Ministry of Agriculture, Forestry and Fisheries announced the Green Food System Strategy, a fairly long-term vision looking 30 years into the future regarding the future of Japanese agriculture. The goal is to reduce the amount of chemical fertilizers used by 30%.

For example, Patent Document 1 describes a method for cultivating fruit and vegetable crops under conditions in which the amount of fertilizer applied is reduced compared to the conventional amount of fertilizer, and the method is characterized in that L-proline is used in combination to suppress a decrease in yield. A novel method for cultivating fruit and vegetable crops is disclosed.

Japanese Patent Application Publication No. 2006-191848

An object of the present invention is to provide a novel yield reduction inhibitor capable of suppressing a decrease in yield due to a decrease in the amount of chemical fertilizer applied to fruit or leafy vegetables crops.

The present invention relates to the following inventions.
[1]
A yield reduction inhibitor containing humic substances as an active ingredient.
[2]
The agent for suppressing a decrease in yield according to [1], which is an agent for suppressing a decrease in yield due to a decrease in the amount of chemical fertilizer applied to fruit vegetables or leafy vegetables.
[3]
The yield reduction inhibitor according to [1] or [2], wherein the humic substance contains at least one selected from the group consisting of humic acid and fulvic acid.
[4]
The yield reduction inhibitor according to any one of [1] to [3], wherein the melanic index of the humic substance is 2.0 or more.
[5]
The yield reduction inhibitor according to any one of [1] to [4], wherein the humic substance has a weight average molecular weight of 200 to 6,000.
[6]
The yield reduction inhibitor according to any one of [1] to [5], wherein the active ingredient is a humic substance-containing liquid containing a humic substance, and the pH of the humic substance-containing liquid is 2.0 to 9.0.
[7]
A method for cultivating fruit vegetable crops or leafy vegetable crops under conditions where the amount of chemical fertilizer applied is lower than the conventional amount of fertilizer, the method comprising an application step of applying a humic substance in combination with the chemical fertilizer.

According to the present invention, it is possible to provide a novel yield reduction inhibitor capable of suppressing a decrease in yield due to a decrease in the amount of chemical fertilizer applied to fruit or leafy vegetables crops.

It is a figure which shows the effect which humic acid has on a leaf area under reduced fertilizer cultivation, (A) is a photograph which shows the measuring method of a leaf area, and (B) is a graph which shows the measurement result of a leaf area. (A) is a graph showing the measurement results of the number of flowers when humic acid is applied under reduced fertilizer cultivation, and (B) is a graph showing the measurement results of the number of fruits when humic acid is applied under reduced fertilizer cultivation. It is a graph. (A) is a graph showing the measurement results of dry mass when the humic acid extract A of the example is applied under reduced fertilizer cultivation, and (B) is a graph showing the measurement results of the humic acid extract B of the example under reduced fertilizer cultivation. It is a graph which shows the measurement result of dry mass when applying.

Hereinafter, modes for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

[Yield yield reduction inhibitor]
The yield reduction inhibitor according to the present embodiment contains a humic substance as an active ingredient.

<Fruit and vegetable crops>
Fruit and vegetable crops are crops that mainly utilize fruits and/or seeds. Examples of fruit and vegetable crops include fruits and vegetables of the nightshade family, beans (seeds and seeds), beans (immature), cucurbits (immature), cucurbits (mature), and the like. Examples of fruits and vegetables of the eggplant family include edible Chinese peppers, tomatoes, cherry tomatoes, eggplants, and peppers and chili peppers such as sweet and long chili peppers, Kagura Nanban, Kidachi chili peppers, shishito peppers, chili peppers, habanero, green peppers, and picante. . Examples of legumes (seeds) include azuki beans, kidney beans, cowpeas, fava beans, soybeans, red beans, Fuji beans, red beans, peas, and radish. Examples of legumes (immature) include green beans, green beans, immature cowpeas, immature black beans, immature fava beans, immature beans, immature Fuji beans, snow peas, and real peas. Examples of cucurbits (immature) include cucumbers, edible gourds, edible loofahs, zucchini, chili peppers, bittern gourds, gourds, gourds, cucurbits, and red-headed gourds. Examples of cucumbers (mature) include pumpkins, watermelons, cucumbers, and melons.

<Leafy vegetables>
Leafy vegetables are crops that utilize their leaves. Examples of leafy vegetable crops include head-heading leafy vegetables, non-heading leafy vegetables, umbelliferous leafy vegetables, lettuces, leafy vegetables other than lettuce, leafy vegetables of the Lamiaceae family, leafy vegetables of the Amaranthaceae family, and other leafy vegetable crops. . Examples of the head-heading leafy vegetables include cabbage, Chinese cabbage, Brussels sprouts, and hybrids between crops included in the head-heading oily leafy vegetables. Examples of non-heading leafy vegetables include turnip, mustard, kale, komatsuna, taa cai, bok choy, pear, pak choy, hata wasabi, mizuna, arugula, thistle, ajimina, aburana, and unno (stems and leaves). ), Otakana, Oyama Sodachi, Cavolo Nero, Kahokuna, Kale cola, Sagami green, Sanukina, Sichuan pressed greens, Senbo greens, Body Chinese greens, Takana, Eat greens, Chingen arugula, Tegoruna, Nabana, etc. Examples include zawana, non-heading Brussels sprouts, beni-na, mochi-na, Yamagata midorina, Raffanobrassica, wasabi, and hybrids between crops included in the non-heading oily leafy vegetables. Examples of leafy vegetables of the Umbelliferae family include caraway (leaves), Japanese cabbage, coriander (leaves), dill (leaves), parsley, fennel (leaves), chervil, mitsuba, celery, Ashitaba, Japanese parsley, toki (leaves), Examples include Maboufuu (leaf) and Botanboufuu. Examples of lettuces include endive, trevis, non-heading lettuce, lettuce, and puntarella. Examples of leafy vegetables other than lettuce include leaf vegetables, edible dandelion, curry plant, tarragon, mugwort, watermelon, kooni tabirako, sawa thistle, leaf burdock, haha. Examples include kogusa, hosoba wadan, maple grass, yacon (stems and leaves), yobusumaso, and yomena. Examples of leafy vegetables of the perilla family include perilla (leaves), oregano, perilla, sage, thyme, basil, mint, marjoram, lemon balm, and rosemary. Examples of leafy vegetables of the Amaranthaceae family include amaranth (stems and leaves), amaranth, spinach, and hijiki. Other leafy vegetable crops include, for example, ice plant, vine, chili pepper (leaf), marsh, moroheiya, kansho (stem and leaf), cabbage, oranda wa mokou, borage, lemongrass, ukogi, shrimp sugusa (stem and leaf). , Okanoori, Kawaraketsumei, cucumber (leaves), edible sorrel, Tsurumurasaki, Dokudami, Hakobe, Habusou (stems and leaves), Yanagita, Yukinoshita, and Lemon verbena.

<Chemical fertilizer>
Chemical fertilizers are chemically manufactured fertilizers, and are different from organic fertilizers that are made from organic matter of animals and plants. Chemical fertilizers can be classified into nitrogenous fertilizers, phosphoric acid fertilizers, potassium fertilizers, compound fertilizers, calcareous fertilizers, and other fertilizers. Examples of nitrogenous fertilizers include urea, ammonium sulfate, ammonium chloride, and lime nitrogen. Examples of phosphoric acid fertilizers include superphosphate lime and molten phosphorous fertilizer. Examples of potassium fertilizers include potassium chloride and potassium sulfate. Examples of compound fertilizers include advanced chemical fertilizers, ordinary chemical fertilizers, and blended fertilizers. Calcareous fertilizers include calcium carbonate fertilizers and slaked lime. Examples of other chemical fertilizers include silicic acid fertilizers and magnesia fertilizers.

If the amount of chemical fertilizer applied is reduced from the conventional amount, the yield will decrease. According to the yield reduction inhibitor according to the present embodiment, it is possible to suppress a reduction in yield due to a decrease in the amount of chemical fertilizer applied to fruit or leafy vegetables crops. That is, according to the yield reduction inhibitor according to the present embodiment, it is possible to reduce the amount of chemical fertilizer applied compared to the conventional amount while suppressing a decrease in yield. The yield reduction suppressing agent according to the present embodiment can be a yield reduction suppressing agent that is associated with a reduction in the amount of chemical fertilizer applied to fruit and vegetable crops or leafy vegetable crops.

<Humic substances>
Humic substances are naturally occurring polymeric organic substances found in soil and terrestrial water. Humic substances include humic acids, which are soluble organic substances, and humins, which are insoluble organic substances.

Humic acids can be further classified into fulvic acid, which is soluble in alkaline and acidic solutions, and humic acid, which is soluble in alkaline solutions and insoluble in acidic solutions. The humic substance may contain at least one selected from the group consisting of humic acid and fulvic acid.

Examples of humic acid include natural humic acid produced naturally in peat and weathered coal, artificial humic acid produced artificially by nitric acid oxidation of lignite, and natural humic acid or artificial humic acid containing sodium, potassium, Examples include humic acid salts neutralized with alkali substances such as ammonia, calcium, and magnesium. Examples of humic acids include fulvic acid, humic acid, nitrofumic acid, ammonium humate, calcium humate, magnesium humate, ammonium nitrofumate, calcium nitrofumate, magnesium nitrofumate, potassium humate, potassium nitrofumate, and the like.

Humic acids can be classified into A type, B type, Rp type and P type. The humic acid may be an Rp-type or a P-type humic acid (Rp/P-type humic acid). Humic acids can be simply classified using the melanic index (MI) described below. Humic acids with an MI of 2.0 or more are classified as Rp/P type.

The melanic index (MI) of humic substances may be 1.5 or more, 2.0 or more, 2.2 or more, 2.5 or more, 3.0 or more, or 3.5 or more, and 6.5 or less , 6.0 or less, 5.5 or less, 5.0 or less, 4.5 or less, 4.0 or less, 3.5 or less, or 3.0 or less.

MI is an index used to classify humic substances (and humic acids), and is the ratio of absorbance at wavelengths of 450 nm and 520 nm (A ₄₅₀ /A ₅₂₀ ) of the absorption spectrum of a sodium hydroxide extract. (Kyoichi Kumada, Chemistry of Soil Organic Matter, 2nd Edition, Gakkai Publishing Center (1981), Japanese Journal of Soil and Fertilization, No. 71, No. 1, p. 82-85 (2000)).

More specifically, MI is calculated by the following method. The sample is ground to a 250 μm sieve quality using a mortar and a 250 μm sieve. Approximately 10 g of the sample is placed in a weighing bottle with a known mass and accurately weighed. This weighing bottle is left in a dryer maintained at a temperature of 105° C. for about 12 hours, then returned to room temperature in a desiccator, and then accurately weighed again. The moisture content of the sample is determined by assuming that the mass loss is moisture. Next, in a 50 ml centrifuge tube, put 0.10 g of the above 250 μm sieved product in dry weight equivalent and 45 ml of 0.5 mol/L sodium hydroxide aqueous solution, and shake at a speed of 250 rpm for about 1 hour at room temperature of 20°C. After cooling, centrifugation was carried out at 3,000 x g for about 10 minutes, and the supernatant was transferred to Advantech No. Filter through 5C filter paper. The absorbance of the filtrate at 450 nm and 520 nm is measured using distilled water as a blank. In this case, if the absorbance at 450 nm is 1.0 or more, add 0.1 mol/L sodium hydroxide aqueous solution to adjust the absorbance to 0.8 or more and less than 1.0, and then measure the absorbance at 520 nm. do. The ratio of (absorbance at 450 nm/absorbance at 520 nm) is calculated and set as MI.

The weight average molecular weight of the humic substance may be from 200 to 6,000, since it can further suppress a decrease in yield due to a decrease in the amount of chemical fertilizer applied. The lower limit of the weight average molecular weight of the humic substance may be, for example, 200 or more, 300 or more, 400 or more, 500 or more, 600 or more, 700 or more, 800 or more, 900 or more, or 1000 or more. The upper limit of the weight average molecular weight of humic substances is, for example, 5,500 or less, 5,000 or less, 4,500 or less, 4,000 or less, 3,500 or less, 3,000 or less, 2,500 or less, 2,000 or less It may be less than or equal to 1,500, less than or equal to 1,200, or less than or equal to 1,000. The humic substance is fulvic acid with a weight average molecular weight of 200 to 800, and/or a weight average molecular weight of 2,500 to 6,000, since it can further suppress a decrease in yield due to a decrease in the amount of chemical fertilizer applied. May contain humic acid.

The weight average molecular weight of the humic substance is measured by the HPSEC method (GPC method) using the Alliance HPLC System manufactured by Waters. The column is Showa Denko SB-803HQ, the standard sample is sodium polystyrene sulfonate, and the detection wavelength is 260 nm. The mobile phase is a 10 mmol/L sodium phosphate buffer containing 25% by mass acetonitrile, the flow rate is 0.8 ml/min, and the column temperature is 40° C. (column oven setting).

The active ingredient may be a humic substance-containing liquid containing humic substances. The pH of the humic substance-containing liquid may be 2.0 to 9.0, since it can further suppress a decrease in yield due to a decrease in the amount of chemical fertilizer applied. The pH of the humic substance-containing liquid is 2.0 or more, 2.5 or more, 3.0 or more, 3.5 or more, 4.0 or more, 4.5 or more, 5.0 or more, 5.5 or more, 6. It may be 0 or more, or 6.5 or more. The upper limit of the pH of the humic substance-containing liquid may be 9.0 or less, 8.0 or less, 7.5 or less, 7.0 or less, or 6.5 or less. The pH of the humic substance-containing liquid is measured by the method described in the Examples below.

The humic substance-containing liquid may be, for example, a humic acid extract. The humic acid extract may be an extract obtained by extracting nitric acid oxides from young coal with an extraction solvent containing water and optionally an alkali.

Young coal is coal that has a lower carbon content than bituminous coal, etc., and is defined as having a carbon content of 83% by mass or less. Examples of young coal include peat, lignite, lignite, subbituminous coal, and the like. Young charcoal may be used alone or in combination of two or more.

Nitrate oxide of young coal is obtained by oxidizing and decomposing young coal with nitric acid. Concentrated nitric acid is preferable as the nitric acid. In terms of safety and reactivity, it is preferable to use nitric acid with a concentration of 40 to 60% by mass. The blending amount of nitric acid (HNO ₃ ) during oxidative decomposition may be 10 parts by mass or more, or 20 parts by mass or more, and 300 parts by mass or less, 250 parts by mass or less, 200 parts by mass or less, based on 20 parts by mass of young coal. The amount may be less than or equal to 150 parts by weight, less than 100 parts by weight, less than 50 parts by weight, less than 36 parts by weight, or less than 20 parts by weight. The blending amount of nitric acid (HNO ₃ ) may be 10 to 20 parts by mass, or 20 to 36 parts by mass, based on 20 parts by mass of young coal. Here, the blending amount of nitric acid is a value converted to 100% nitric acid (100% HNO ₃ ).

The temperature during oxidative decomposition may be, for example, 70 to 95°C. As a starter for the oxidation reaction, heating it to 70-95°C in a hot water bath or the like will help the oxidation reaction proceed quickly. The reaction time may be, for example, 20 minutes or more, 0.5 hours or more, or 1 hour or more, and 6 hours or less, 4 hours or less, or 1 hour or less.

A humic substance-containing liquid can be obtained as a liquid by, for example, stirring nitric acid oxide of young coal (hereinafter referred to as a humic substance crude product) and an extraction solvent containing water and an alkali, and then performing a solid-liquid separation process. can get.

Examples of the alkali include hydroxide and ammonia. Examples of the hydroxide include alkali metal hydroxides and ammonium hydroxide. The hydroxide is preferably an alkali metal hydroxide. Examples of the alkali metal hydroxide include potassium hydroxide, sodium hydroxide, and the like. The hydroxide is preferably one or more of potassium hydroxide, sodium oxide, and ammonium hydroxide (ammonia water). The pH of the extraction solvent may be 0.5-7.0, 0.5-4.0 or 1.0-3.0.

The temperature (extraction temperature) when extracting the crude humic substance with the extraction solvent may be, for example, 40 to 90°C from the viewpoint of further suppressing freezing and quality deterioration of the extract. The time for extracting the crude humic substance with the extraction solvent (extraction time) may be, for example, 0.5 hours or more, 24 hours or less, or 1 hour or less.

The amount of extraction solvent relative to the amount of raw material young charcoal used to prepare the humic substance crude product is defined as the solid-liquid ratio. For example, when 100 g (100 mL) of extraction solvent (water) is added to a crude product prepared from 20 g of young charcoal, the solid-liquid ratio (extraction solvent/young charcoal) is 5. The solid-liquid ratio may be 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, or 10 or more, and 15 or less, 13 or less, 11 or less, 9 or less, 7 or less, or 6 or less. It may be. The solid-liquid ratio can be adjusted by adding water. The solid-liquid ratio may be adjusted to a desired solid-liquid ratio after pH adjustment. The solid-liquid separation method may be centrifugation, filter press, or the like.

The total organic carbon concentration (TOC) of the humic substance-containing liquid is 15,000 mg/L or more, 15,300 mg/L or more, 15,500 mg/L or more, 16,000 mg/L or more, 16,500 mg/L or more, 17. 000mg/L or more, 17,500mg/L or more, 18,000mg/L or more, 18,500mg/L or more, 19,000mg/L or more, 19,500mg/L or more, 20,000mg/L or more, or 20, It may be 500 mg/L or more. The TOC of the humic substance-containing liquid is 75,000 mg/L or less, 70,000 mg/L or less, 65,000 mg/L or less, 60,000 mg/L or less, 55,000 mg/L or less, 50,000 mg/L or less, 45,000 mg/L or less, 40,000 mg/L or less, 35,000 mg/L or less, 30,000 mg/L or less, 25,000 mg/L or less, 24,000 mg/L or less, 23,000 mg/L or less, or It may be 22,000 mg/L or less.

The method for measuring TOC of a humic substance-containing liquid is defined as follows. TOC is a value obtained by centrifuging a humic substance-containing liquid at 3,000×g and measuring the supernatant liquid using a combustion catalytic oxidation method using a total organic carbon meter (TOC-L manufactured by Shimadzu Corporation). When non-humic substances such as urea, which is a fertilizer component, are included, the above-mentioned fractions (humic acid fraction and fulvic acid fraction) are separated according to the method of the International Society of Humic Substances (Fujitake, Humic Substances Research Vol. 3, P1-9). The TOC of the humic substance-containing liquid is determined by the following method.

The yield reduction inhibitor according to the present embodiment may be, for example, liquid or solid such as powder. The powdered agent can be obtained as a redissolved powder by, for example, drying up the liquid yield reduction inhibitor by freeze-drying or the like.

<Other ingredients>
The yield reduction inhibitor according to the present embodiment may contain components other than humic substances. Examples of other components include other fertilizer components, spreading agents, agricultural chemicals, plant growth regulators, seaweed extracts, amino acids, plant extracts, microbial extracts, and the like.

[Cultivation method]
The method for cultivating fruit and vegetable crops or leafy vegetable crops according to the present embodiment is a method for cultivating fruit and vegetable crops or leafy vegetable crops under conditions where the amount of chemical fertilizer applied is lower than the conventional amount of fertilizer. The method includes an application step of applying a humic substance in combination with a chemical fertilizer.

Examples of methods for applying humic substances to fruit and leafy crops include soil irrigation, soil mixing, and application to the foliage or plant base.

The customary application amount of chemical fertilizers can be easily known by those skilled in the art (farmers, hydroponic growers, etc.). For example, in Japan, reference may be made to the "Fertilizer Application Standards by Crop" established by each prefecture. Farmers in each prefecture usually cultivate crops in accordance with this standard, setting the amount of fertilizer appropriate for the region of the prefecture.

The conventional application amount of chemical fertilizers is typically determined based on the three components of nitrogen (nitrate nitrogen), phosphoric acid, and potassium. If the amount of chemical fertilizer applied is lower than the fertilizer application standard set in the fertilizer application standards for each crop in at least one of nitrogen (nitrate nitrogen), phosphoric acid, and potassium, the amount of chemical fertilizer applied is the conventional fertilizer application amount. It is determined that the condition is lower than that of

The amount of chemical fertilizer applied may be 10% or more lower than the conventional fertilization amount, and may be 20% or more or 30% or more lower than the conventional fertilization amount.

The amount and application period of humic substances are not particularly limited; in the case of soil application, the total organic carbon concentration is 7000 to 20000 mg/L once per fruit tree, or the total organic carbon concentration is 0.1 to 1000 mg/L per month. It can be applied 1 to 30 times per day or daily at a total organic carbon concentration of 0.1 to 100 mg/L, and in the case of foliar application, it can be applied once to a month at a total organic carbon concentration of 0.1 to 1000 mg/L. It can be 12 times.

As one embodiment of the present invention, a method for suppressing a decrease in yield of fruit and vegetable crops or leafy vegetables is provided. The method may be a method for suppressing a decrease in yield due to a decrease in the amount of chemical fertilizer applied to fruit and vegetable crops or leafy vegetables. The specific embodiments described as the embodiments of the yield reduction inhibitor and cultivation method can be applied to the method of suppressing the reduction in yield of fruit vegetables or leafy vegetables.

As one embodiment of the present invention, there is provided the use of humic acid to suppress yield loss of fruit and vegetable crops or leafy vegetable crops. The use may be the use of humic acid to suppress a decrease in yield due to a decrease in the amount of chemical fertilizer applied to fruit and vegetable crops or leafy vegetables. For the use of humic acid to suppress yield reduction of fruit and leafy vegetables crops, the specific embodiments described as embodiments of the yield reduction inhibitor and cultivation method can be applied.

As one embodiment of the present invention, a humic acid is provided for use in suppressing yield loss of fruit and vegetable crops or leafy vegetable crops. The humic acid may be used to suppress a decrease in yield due to a decrease in the amount of chemical fertilizer applied to fruit or leafy vegetables crops. The specific embodiments described as the embodiments of the yield reduction inhibitor and cultivation method can be applied to humic acid for use in suppressing yield reduction of fruit and leafy vegetables crops.

As one embodiment of the present invention, there is provided the use (application) of humic acid for the production of a yield reduction suppressant for fruit and vegetable crops or leafy vegetables. The use may be the use of humic acid for the production of an agent for suppressing yield loss due to a reduction in the amount of chemical fertilizer applied to fruit or leafy vegetables crops. The specific embodiments described as the embodiments of the yield reduction inhibitor and cultivation method can be applied to the use of humic acid for producing the yield reduction inhibitor for fruit and leafy vegetables crops.

Hereinafter, the present invention will be explained more specifically based on Examples. However, the present invention is not limited to the following examples.

[Preparation of humic acid extract A]
In a draft, 500 g of lignite with a carbon content of 77% by mass was placed in a 1,000 ml beaker, and 625 g of nitric acid with a concentration of 48% by mass (60 parts by mass of 100% nitric acid per 100 parts by mass of young coal) was added. . The oxidation reaction was carried out in a water bath at 80°C for 3 hours. The crude product containing humic acid obtained in this operation was subjected to the following extraction operation.
Approximately 900 mL of 0.5 mol/L potassium hydroxide aqueous solution was added to 100 g of this crude product, and while monitoring with a pH meter, 1.0 mol/L potassium hydroxide aqueous solution was appropriately added to adjust the pH to 6.5. Water was added so that the solid-liquid ratio was 1:10, and extraction was performed at 80°C for 1 hour. This extract was centrifuged at 3,000×g, the resulting supernatant was diluted appropriately, and the weight average molecular weight, total organic carbon concentration (TOC), and melanic index (MI) were measured.

The MI of humic acid in humic acid extract A was 2.2. The total organic carbon concentration (TOC) of humic acid extract A was 34,000 mg/L. The weight average molecular weight of humic acid in humic acid extract A was 4,300. The pH of humic acid extract A was 6.0 to 8.0.

[Preparation of humic acid extract B]
In a draft, 500 g of lignite with a carbon content of 77% by mass was placed in a 1,000ml beaker, and 1562.5g of nitric acid with a concentration of 48% by mass (150 parts by mass of 100% nitric acid per 100 parts by mass of young coal) was added. Added. The oxidation reaction was carried out in a water bath at 80°C for 3 hours. The crude product containing humic acid obtained in this operation was subjected to the following extraction operation.
Approximately 450 mL of 0.5 mol/L potassium hydroxide aqueous solution was added to 100 g of this crude product, and while monitoring with a pH meter, 1.0 mol/L potassium hydroxide aqueous solution was appropriately added to adjust the pH to 2.0. Water was added so that the solid-liquid ratio was 1:5, and extraction was performed at 80°C for 1 hour. This extract was centrifuged at 3,000×g, the resulting supernatant was diluted appropriately, and the weight average molecular weight, total organic carbon concentration (TOC), and melanic index (MI) were measured.

The MI of humic acid in humic acid extract B was 4.8. The total organic carbon concentration (TOC) of humic acid extract B was 22,000 mg/L. The weight average molecular weight of humic acid in humic acid extract B was 530. The pH of humic acid extract B was 2.0 to 3.0.

[Weight average molecular weight]
The weight average molecular weight of humic acid was measured by HPSEC method (GPC method) using Alliance HPLC System manufactured by Waters. The column used was Showa Denko SB-803HQ, the standard sample was sodium polystyrene sulfonate, and the detection wavelength was 260 nm. The mobile phase was a 10 mmol/L sodium phosphate buffer containing 25% by mass of acetonitrile, the flow rate was 0.8 ml/min, and the column temperature was 40° C. (column oven setting).

[Total organic carbon concentration (TOC)]
The TOC of the humic acid extract was measured using a total organic carbon meter (TOC-L manufactured by Shimadzu Corporation) using a combustion catalytic oxidation method.

[Melanic Index (MI)]
The sample was ground to a 250 μm sieve grade using a mortar and a 250 μm sieve. Approximately 10 g of the solution was placed in a weighing bottle with a known mass and accurately weighed. This weighing bottle was left in a dryer maintained at a temperature of 105° C. for about 12 hours, and then returned to room temperature in a desiccator and then accurately weighed again. The water content of the sample was determined by assuming that the mass loss was water. Next, in a 50 ml centrifuge tube, put 0.10 g of the above 250 μm sieved product in dry weight equivalent and 45 ml of 0.5 mol/L sodium hydroxide aqueous solution, and shake at a speed of 250 rpm for about 1 hour at room temperature of 20°C. After cooling, centrifugation was carried out at 3,000 x g for about 10 minutes, and the supernatant was transferred to Advantech No. Filtered through 5C filter paper. The absorbance of the filtrate at 450 nm and 520 nm was measured using distilled water as a blank. In this case, if the absorbance at 450 nm is 1.0 or more, add 0.1 mol/L sodium hydroxide aqueous solution to adjust the absorbance to 0.8 or more and less than 1.0, and then measure the absorbance at 520 nm. did. The ratio of (absorbance at 450 nm/absorbance at 520 nm) was calculated and defined as MI.

[Test plants and cultivation method before application]
Experimental tomato (Solanum lycopersicum cv. Micro-Tom) seeds were sown two at a time in rock wool (Grodan) cut into 4.8 (D) * 4.8 (W) * 2.5 (H) mm. After about 10 days, the ones that germinated well were kept and used for cultivation tests. Approximately 200 rock wool impregnated with tap water were used, and after sowing, tap water was given as appropriate to prevent drying. The cultivation environment in the incubator (EYELA, FLI-2010H-LED) is 20°C, 80% RH, dark conditions during the sowing to germination period, and 20°C, 55% RH, weak light conditions from the germination period to the 14th day of sowing. After the 14th day of sowing, cultivation was carried out at 25° C./16 hr/light setting of 3 L and 20° C./8 hr/dark conditions.

[Humic acid and nutrient solution application conditions]
Plants on the 14th day of sowing were divided into 12 individual polypropylene bats (AS ONE 1-4618-01) to prevent variations in growth between the application areas. Cultivation was carried out using the OAT-A formulation mixed with A. The test area was set at 70, 50, 20, or 5 when the OAT-A prescription concentration was 100, and the humic acid materials were humic acid extract A and humic acid extract B at a TOC concentration of 60 ppm for each OAT. Mixed and applied. In addition, OAT was cultivated for about 80 days after sowing, with each bat being renewed once a week. OAT-A is a general liquid fertilizer used for growing fruits and vegetables.

The condition where the OAT-A prescription concentration is 100 is the condition where chemical fertilizer is applied at the conventional fertilizer amount. The conditions where the OAT-A prescription concentration is 70, 50, 20, and 5 are conditions where the chemical fertilizer is 30%, 50%, 80%, and 95% lower than the conventional fertilizer application amount, respectively.

[Measurement items/methods]
All cultivated plants were measured for each measurement item, and the average value data of a median of 8 plants out of the top 12 plants in each application area was used.

(1) Leaf area/Canopy Area Index (CAI)
FIGS. 1(A) and (B) show the measurement results of leaf area when humic acid extract A was used as the humic acid material for testing. As shown in FIG. 1(A), the plant under cultivation was photographed from the horizontal direction (directly above) and used for image analysis. A scale with a known area of 20 mm x 20 mm was placed during photographing (arrow in FIG. 1(A)), and a standard scale of 400 mm ² (4 cm ² ) was used during image analysis. Image analysis software LIA32 (URL: https://www.agr.nagoya-u.ac.jp/~shinkan/LIA32/) was used. CAI was calculated 35 days after seeding. FIG. 1(B) shows the measurement results of leaf area. In FIG. 1(B), a humic acid material is used as the material (+), and the material (+) contains nutrients derived from the humic acid material. In Figure 1 (B), material (-) does not use humic acid materials, but material (-) has a considerable amount of nutrients added at the time of material addition. Humic acid chelates nutrients (minerals, etc.), making it difficult for nutrients to become insolubilized in the soil, making it easier for plant roots to absorb nutrients.

(2) Survey on the number of flowers and fruits The cumulative number of flowers and fruits bloomed for each individual was measured every week from the flowering period. Regarding the number of fruits, only those that were enlarged by 10 mm or more were used for data. The final survey was conducted approximately 80 days after sowing. FIG. 2(A) shows the measurement results of the number of flowers, and FIG. 2(B) shows the measurement results of the number of fruits. "A_60" in FIGS. 2(A) and 2(B) means that humic acid extract A was applied at a TOC concentration of 60 ppm.

(3) Dry mass All fruits were harvested from the plants about 80 days after sowing, and the leaves and stems were separated and the dry mass of each was measured. Drying was carried out at 70° C. for 16 hours or more using a constant temperature dryer. FIG. 3(A) and FIG. 3(B) show the measurement results of dry mass when humic acid extract A and humic acid extract B were used as humic acid materials, respectively.

As shown in Figure 1 (B), Figures 2 (A) and (B), and Figure 3 (A) and (B), the application of humic acid materials reduces the yield due to the decrease in the amount of chemical fertilizer applied. suppressed.

Claims

A yield reduction inhibitor that contains humic substances as an active ingredient.
The agent for suppressing a decrease in yield according to claim 1, which is an agent for suppressing a decrease in yield due to a decrease in the amount of chemical fertilizer applied to fruit and vegetable crops or leafy vegetables.
The yield reduction inhibitor according to claim 1 or 2, wherein the humic substance contains at least one selected from the group consisting of humic acid and fulvic acid.
The yield reduction inhibitor according to claim 1 or 2, wherein the humic substance has a melanic index of 2.0 or more.
The yield reduction inhibitor according to claim 1 or 2, wherein the humic substance has a weight average molecular weight of 200 to 6,000.
The active ingredient is a humic substance-containing liquid containing the humic substance,
The yield reduction inhibitor according to claim 1 or 2, wherein the humic substance-containing liquid has a pH of 2.0 to 9.0.
A method of cultivating fruit and leafy vegetables crops under conditions where the amount of chemical fertilizer applied is lower than the amount of conventional fertilizer, the method comprising:
A method comprising applying a humic substance in combination with the chemical fertilizer.