JP7611706B2 - Fertilizer or plant growth regulator containing lactic acid bacteria fermentation product - Google Patents

Description

The present invention relates to an inhibitor for inhibiting bolting in root vegetables and leafy vegetables, utilizing a composition containing a lactic acid bacteria fermentation product, and a method thereof.

Leafy and root vegetables are known to develop flower stalks due to changes in temperature conditions, changes in day length, or a longer cultivation period; this phenomenon is called bolting. In leafy and root vegetables, bolting causes the growth of the leaves and roots used as edible parts to stop or take on a form that is different from the desired form, and also reduces the taste, resulting in a significant decrease or loss of commercial value.

There are various known causes of flower bolting, but it is known that it occurs due to environmental stresses such as low light, low temperature, high temperature, lack of fertilizer, lack of water, or excess water, rather than optimal environmental factors.

Known methods for suppressing bolting include the application of 5-aminolevulinic acid, its derivatives, or its salts (Patent Document 1), adjusting the hours of sunlight using LED lighting or the like (Patent Document 2), using callus induction (Patent Document 3), and using abscisic acid, which is known as a plant hormone (Patent Document 4).

In addition, various methods for regulating plant growth are being investigated. For example, because phenyllactic acid has a root-promoting effect, methods using lactic acid bacteria are being investigated (Patent Document 5).

In the food industry, lactic acid bacteria are used in a variety of ways, including by utilizing the intestinal regulating effects of lactic acid bacteria and by using lactic acid bacteria fermentation compositions as seasonings (Patent Documents 6 and 7).

Patent Publication 2011-121878 Patent Publication No. 2007-252211 JP 6-343360 A JP 4-217603 A Patent Publication 2014-080398 WO2018/110633 Patent Publication No. 2020-103045

The objective of the present invention is to provide a method for imparting resistance to plants, such as leafy vegetables and root vegetables, to biological, physical, or chemical stresses that affect plant growth, in order to improve the yield of the plants.

In light of this current situation, the inventors conducted intensive research and discovered that applying a lactic acid bacteria fermentation composition containing specific ingredients to root vegetables under normal culture conditions significantly reduced the bolting rate of onions. This led to the completion of the present invention, a composition and method for imparting resistance to plants against biological, physical, or chemical stresses that affect growth.

The present invention is as follows.
(1) A plant growth regulator containing a lactic acid bacteria fermentation liquid.
(2) The plant growth regulator of (1), which contains 5 to 70% by mass of mannitol, 1 to 10% by mass of acetic acid, and 1 to 10% by mass of monosodium glutamate. (3) A method for producing the plant growth regulator of (1) or (2), which comprises a step of fermenting a lactic acid bacterium expressing mannitol-2-dehydrogenase in a medium containing a yeast extract containing 5% or more by mass of glutamic acid, and fructose.
(4) A method for inhibiting bolting in leafy vegetables or root vegetables, which comprises applying the plant growth regulator according to (1) or (2).

According to the present invention, the bolting rate of leafy vegetables or root vegetables can be reduced, and therefore the harvest time of leafy vegetables or root vegetables can be adjusted, which contributes to improving the rate of high-quality products. Although the mechanism by which the bolting rate is reduced according to the present invention has not been elucidated, it is speculated that this is due to the application of the lactic acid bacteria fermentation product promoting the assimilation, conversion, and use of nutrients by the plants.

Results of high quality rate when applied to onions Results of bolting rate by application to onion

The lactic acid bacteria fermentation liquid contained in the plant growth regulator of the present invention is obtained by cultivating lactic acid bacteria having mannitol-2-dehydrogenase in a medium containing fructose and yeast extract, and concentrating the culture supernatant. If powderization is required, drying is possible by using an appropriate excipient. The plant growth regulator of the present invention contains 5 to 70% by mass of mannitol, 1 to 10% by mass of acetic acid, and 1 to 10% by mass of sodium glutamate. It may also contain 1.5 to 20% by mass of lactic acid.

The mannitol of the present invention is obtained from the fructose used in the medium by lactic acid bacteria expressing mannitol-2-dehydrogenase in the latter stage. Therefore, the lactic acid bacteria fermentation is performed so that the mannitol content of the present invention is the above-mentioned content. The mannitol content can also be adjusted with an excipient such as dextrin.

There are no particular limitations on the lactic acid bacteria used in the production of the present invention, so long as they express mannitol-2-dehydrogenase and can be used in food production. For example, lactic acid bacteria that express mannitol-2-dehydrogenase, such as those of the Lactobacillus and Leuconostoc genera, can be used.

Yeast extract is added to the medium used for the lactic acid bacteria fermentation of the present invention. The yeast extract used contains 5% or more glutamic acid. Yeast extract containing 15% or more, more preferably 20% or more glutamic acid is used. The content of the yeast extract added to the medium may be the same as that of yeast extract normally used in lactic acid bacteria fermentation, and can be adjusted as desired. Such yeast extract is produced from Torula yeast, brewer's yeast, baker's yeast, etc. as raw materials. Commercially available yeast extracts may also be used. Commercially available yeast extracts include "Ajitop" from Mitsubishi Corporation Life Sciences, "Hyper Meest" from Asahi Group Foods, and "Himax GL" from Fuji Foods.
In the present invention, the glutamic acid content refers to the free glutamic acid in the dry powdered yeast extract, and was measured by an amino acid analyzer L8800 (manufactured by Hitachi) in a conventional manner.
By using such yeast extract in the medium, a plant growth regulator containing sodium glutamate can be obtained in the lactic acid fermentation liquor of the present invention. The sodium glutamate content in the lactic acid fermentation liquor of the present invention varies depending on the amount of yeast extract added to the medium, but if the amount added is as in the examples of the present application, the content can be 2 mass% or more.

In addition to the yeast extract from the previous step, fructose is used as the medium composition for fermenting the lactic acid bacteria from the previous step. Fructose and glucose can also be used in combination. Liquid sugars containing these can also be used.

In producing the seasoning of the present invention by fermentation, magnesium chloride, bittern, and other components necessary for lactic acid bacteria fermentation, such as a nitrogen source, a carbon source, vitamins, etc., which are added to a medium during normal lactic acid bacteria fermentation, may be added. The amount of each component added may be appropriately selected from the amounts and types that a person skilled in the art can select for lactic acid bacteria culture.

The method for producing the plant growth regulator of the present invention will be described below with more specific examples.
The above-mentioned medium composition is mixed by a method generally used for lactic acid bacteria fermentation. For example, 100-150 g/L of fructose and 10-50 g/L of yeast extract are mixed and heat sterilized. When minerals necessary for lactic acid bacteria fermentation are added, 0.05-5 ml/L of bittern or the like may be further mixed. After cooling, lactic acid bacteria are cultured. 10-60 g/L of glucose can also be used as a medium component.

The culture conditions in the present invention can be the temperature and pH generally employed in lactic acid bacteria fermentation. Although this varies depending on the species of bacteria used, the culture temperature is generally 20°C to 40°C, and preferably 25°C to 30°C. Furthermore, semi-anaerobic conditions are preferred. During culture, the pH of the culture solution decreases due to the production of organic acids, so the pH during culture may be adjusted with sodium hydroxide, potassium hydroxide, or the like to maintain a pH favorable for the growth of lactic acid bacteria. For example, sodium hydroxide is added appropriately to adjust the medium pH to, for example, 5.0 to 6.0.

The plant growth regulator of the present invention can be obtained by recovering the culture supernatant, which is a lactic acid bacteria fermentation liquid. Specifically, after the end of the culture, the pH of the medium is appropriately adjusted using sodium hydroxide, potassium hydroxide, etc., if necessary. After the heat treatment, the bacterial cells are removed by centrifugation or filtration, and the culture supernatant is recovered, thereby obtaining the product of the present invention. The recovered culture supernatant may be used as is, but it can also be concentrated and dried. There are no particular limitations on the drying method that can be used, and known drying methods such as spray drying, drum drying, and freeze drying can be used.

The lactic acid bacteria fermentation liquid of the present invention produced by the above-mentioned method contains 5 to 70% by mass of mannitol, 1 to 10% by mass of acetic acid, and 1 to 10% by mass of sodium glutamate. The lactic acid content may be 1.5 to 20% by mass. Those skilled in the art of lactic acid bacteria fermentation can appropriately adjust the content of each component within the above ranges.

Furthermore, the plant growth regulator of the present invention may be blended with other plant growth regulators, sugars, nitrogen-containing compounds, acids, alcohols, vitamins, trace elements, metal salts, chelating agents, preservatives, antifungal agents, etc., as necessary. These blends can be blended without restrictions within the scope of the effect of the present application, and those that can be appropriately selected by a person skilled in the art can be blended. Some examples of other plant growth regulators include indole acetic acid, indole butyric acid, 1-naphthylacetamide agents, 4-CPA agents, gibberellin, cloxifonac, bezylaminopurine, forchlorfenuron, paclobutrazol, uniconazole, inapenfide, chlormequat, calcium carbonate agents, etc. Examples of sugars include glucose, sucrose, galactose, xylose, arabinose, etc., and in addition to mannitol produced by lactic acid bacteria fermentation, mannitol may be further added within the content range of the present invention. Examples of nitrogen-containing compounds include amino acids and ammonia. Examples of acids include lactic acid and acetic acid produced by lactic acid bacteria fermentation, which may be added within the range of the content of the present invention, as well as other organic acids, sulfuric acid, phosphoric acid, polyphosphoric acid, etc. Examples of alcohols include methanol and ethanol, and examples of vitamins include vitamin C, B vitamins, nicotinamide, nicotinic acid, and folic acid. Examples of metal salts include calcium salts, potassium salts, and magnesium salts, and examples of trace elements include boron, manganese, zinc, copper, iron, molybdenum, and chlorine.

The plant growth regulator of the present invention can be used as a fertilizer. The method of application to plants is not particularly limited as long as it is a method that contacts plant bodies such as roots, stems, and leaves, and any application method known in the agricultural and horticultural fields can be adopted. The method of application to plants can be appropriately determined depending on the type of target plant, etc. For example, application by stem and leaf spray, immersion treatment, soil irrigation, seed treatment, hydroponic solution treatment, fumigation treatment, room temperature fume treatment, etc. can be mentioned as preferred examples. The method of the present invention can be used without being limited by the cultivation form such as soil cultivation or hydroponic cultivation. The application amount can be appropriately determined by a person skilled in the art depending on the weather conditions, formulation form, application time, application method, application location, target crop, etc. There is no limit to the number of applications, and it can be applied once or multiple times. When applying multiple times, the methods described in the present specification can be combined. For onions, a method of spraying the leaves on the leaves during the first stem and leaf recovery period after wintering and the second time during the bulb thickening period can be exemplified.

There are no particular limitations on the cultivation conditions for the plants to which the composition is applied, and the cultivation conditions may be appropriately selected by a person skilled in the art depending on the type of plant to which the composition is applied, the region, the season, etc.

The plants to which the present invention is applied are not particularly limited as long as they are leafy or root vegetables, but examples include the Liliaceae family, such as onion, garlic, shallot, Chinese chive, leek, chives, and shallots, the Chenopodiaceae family, such as spinach and sugar beet, the Brassicaceae family, such as rape, komatsuna, Chinese cabbage, cabbage, radish, and turnip, the Asteraceae family, such as lettuce, garland chrysanthemum, and burdock, the Umbelliferae family, such as carrot and celery, the Zingiberaceae family, such as ginger and myoga, and others, such as potato, Chinese yam, Chinese yam, taro, lotus root, sweet potato, and bamboo shoot. Furthermore, there is no particular limit to the varieties of these plants that can be used.

The present invention will now be described in more detail with reference to the following examples, but these are merely illustrative and the present invention is not limited to these examples.

(Example of production of lactic acid bacteria fermentation composition)
A medium was prepared by mixing and sterilizing 60g/L glucose, 150g/L fructose, and 50g/L Ajitop (Kohjin Life Sciences). Lactic acid bacteria (Leuconostoc pseudomesenteroides (ATC12291)) were pre-cultured in MRS liquid medium at 37°C for 1 day. 1L of the medium and 10ml of the pre-cultured lactic acid bacteria were placed in a 2L jar fermenter and cultured at 30°C. Aeration was not performed, and the stirring speed was 70 rpm under semi-anaerobic conditions. During the culture, the culture solution was controlled to pH 5.3 with sodium hydroxide, and cultured for 96 hours. After the culture was completed, the pH was adjusted to 6.0 with sodium hydroxide, heated at 90°C for 10 minutes, and then centrifuged at 8,000 rpm for 10 minutes to separate the bacteria and recover the culture supernatant. The collected supernatant was concentrated with an evaporator to obtain a seasoning with a Brix of 70%, which was used as the sample of Example 1. The mannitol content in this sample was 50% by mass. HPLC was used to analyze mannitol, and the measurement conditions were: detector: RI, mobile phase: ultrapure water, column: SUGAR SP0810, column temperature: 80°C, and flow rate: 0.7 ml/min. Dextrin was added to the obtained sample to adjust the mannitol content to 25% by mass, and the sodium glutamate content after the addition of dextrin was 2.7% by mass. In addition, the acetic acid content after the addition of dextrin was 4.0% by mass, and the lactic acid content was 7.0% by mass.

(Application test to onions)
Onions (Neo Earth) were planted in a field and cultivated according to conventional methods. Slow-release fertilizer (sigmoid type) or slow-release fertilizer (linear type) (both from MC Ferticom) was used. The onions were planted three months after sowing, and harvested seven months later for investigation.
The product of the present invention was applied to rice seedling boxes (size: length 580 x width 280 mm x thickness 28 mm) at 2.0 g per seedling box, twice by foliar spraying, the first time at 19 weeks (when stems and leaves recover after wintering) and the second time at 23 weeks (when bulbs begin to thicken) after planting. For the products other than the present invention, the usual amount of the plant growth agent was applied. Planting was carried out on two sides (designated north and south).
The results are shown in Figure 1 (excellent product rate) and Figure 2 (stalk bolting rate). 1: control area, 2: liquid fertilizer containing hydrogen peroxide, 3: fertilizer derived from plant extract, 4: seaweed extract fertilizer, and 5: product of the present invention.

In the test plots where the product of the present invention was applied, the bolting rate significantly decreased and the rate of excellent products increased.

Claims (3)

A plant growth regulator containing a lactic acid bacteria fermentation liquid containing 5-70% by mass of mannitol, 1-10% by mass of acetic acid, and 1-10% by mass of monosodium glutamate The method for producing the plant growth regulator of claim 1 includes a step of fermenting lactic acid bacteria expressing mannitol-2-dehydrogenase in a medium containing yeast extract containing 5% by mass or more of glutamic acid and fructose. A method for inhibiting bolting in leafy or root vegetable plants, comprising applying the plant growth regulator of claim 1.