JP7687709B2 - Environmental stress alleviation agent for plants, plant growth promoter, and method of using the same - Google Patents

Description

This disclosure relates to an environmental stress alleviator for plants, a plant growth promoter, and a method for using the same.

Climate change, including global warming, is increasing abiotic stress on plants, raising concerns about its impact on yield and quality. In Japan, temperatures rise significantly in the summer, causing heat stress to plants. High temperature stress can cause a decrease in germination rate, inhibition of early growth, elongation, and pests and diseases, even if the bed soil retains sufficient moisture. In addition, in greenhouse cultivation, it is difficult to lower the temperature at night, making it difficult to produce high-quality vegetables. Methods for dealing with high temperature stress include raising seedlings in cool nights, raising seedlings in cool highlands, and cultivating in a shaded area, but no satisfactory methods have been established.

In recent years, the use of biostimulant materials has been attracting attention as a measure against environmental stress in plants, such as high temperature stress. Biostimulant materials currently available on the domestic and international market are made from humus, seaweed, amino acids, minerals, microbial materials, etc. For example, it has been reported that L-arginine promotes plant growth under high temperature conditions (see Non-Patent Document 1).

Matysiak, K. et al. (2020) Agronomy 10:769. doi: 10.3390/agronomy10060769

However, the effects of the above biostimulant materials were not sufficient. Therefore, there was a need to develop more useful and powerful environmental stress alleviators and plant growth promoters.

The objective of this disclosure is to provide a new plant environmental stress alleviator and plant growth promoter that has an excellent effect of alleviating environmental stresses such as high temperatures.

As a result of various investigations to solve the above problems, the present inventors have found that applying an extract of eggplant residue, a type of unused biomass, together with calcium ions to a plant can endow the plant with resistance to environmental stresses such as high temperatures, and that the effect is greater than that of conventional biostimulant materials. The present inventors have also found that when an extract of unused biomass other than eggplant residue is used, the same or greater effect can be obtained as with eggplant residue, and that these new materials can be manufactured more simply and are easier to use than conventional biostimulant materials. Based on these findings, the present disclosure has been completed.

That is, the present disclosure provides an agent for alleviating environmental stress in plants, which contains a plant extract and calcium ions. The present disclosure also provides a plant growth promoter, which contains a plant extract and calcium ions.

The present disclosure further provides a method for alleviating environmental stress in a plant by applying the above-mentioned plant environmental stress alleviator to the plant. The present disclosure also provides a method for promoting plant growth by applying the above-mentioned plant growth promoter to the plant.

In this disclosure, by applying plant extracts such as eggplant together with calcium ions to plants, it is possible to endow the plants with resistance to environmental stresses such as high temperatures, and the effect is greater than that of conventional biostimulant materials. This effect is presumably due to the activation of the plants' inherent high temperature stress resistance function by neurotransmitters such as acetylcholine or acetylcholinesterase inhibitors and calcium ions contained in the plant extract, but the detailed mechanism has yet to be elucidated.

In this way, the present disclosure can provide a new environmental stress alleviator and plant growth promoter that has excellent effects of reducing environmental stresses such as high temperatures.

FIG. 1 is a photographic image showing a high temperature resistance test using eggplant sprout extract and eggplant pulp extract (without added calcium) (Test Example 2). FIG. 1 is a photographic image showing a high temperature resistance test using eggplant sprout extract and eggplant pulp extract (calcium 0.5 mM) (Test Example 2). FIG. 1 is a photographic image showing a high temperature resistance test using eggplant sprout extract and eggplant pulp extract (calcium 1.0 mM) (Test Example 2). 1 is a graph showing the results of a high temperature resistance test (2 weeks) using eggplant sprout extract and eggplant pulp extract (Test Example 2). In the figure, the vertical axis indicates yield (fresh weight (mg/plant)), the horizontal axis indicates treatment group, the bars indicate standard deviation, and different letters indicate significant differences (LSD method) at a significance level of 5%. 1 is a graph showing calcium concentrations in lettuce seedlings after completion of the test in Test Example 2. In the figure, (A) shows the results for no calcium addition, (B) for 0.5 mM calcium, and (C) for 1.0 mM calcium. In each graph, the vertical axis shows Ca concentration (%) and the horizontal axis shows yield (fresh weight (mg/plant)). 1 is a graph showing the results of a high temperature resistance test (2 weeks) using an environmental stress alleviator containing an extract from a plant other than eggplant (Test Example 3). In the figure, the vertical axis shows the relative yield (%) and the horizontal axis shows the treatment area. 1 is a graph showing the high temperature stress alleviation effect of various standard substances and calcium ions (Test Example 4). In the figure, the vertical axis shows the relative yield (%) and the horizontal axis shows the treatment group.

The environmental stress relief agent for plants of this embodiment will be described in detail below. The environmental stress relief agent of this embodiment is characterized by containing a plant extract and calcium ions.

In this specification, "environmental stress" refers to abiotic stress that a plant experiences, such as high temperature stress, low temperature stress, salt stress, and oxidative stress. The form of the environmental stress alleviator is not particularly limited, but it is preferably in the form of an aqueous solution.

The plant from which the "plant extract" is extracted is preferably unused biomass, such as organic waste from food processing plants or crop residues generated after harvesting in agriculture, from the viewpoint of reducing production costs and solving food waste problems. In addition, the plant preferably contains a neurotransmitter and/or an acetylcholinesterase inhibitor. The neurotransmitter may be one or more selected from acetylcholine, epinephrine, norepinephrine, serotonin, dopamine, amino acids (particularly glutamic acid, alanine, glycine, proline, leucine, threonine, phenylalanine, GABA, arginine, histidine, cysteine, and asparagine), preferably acetylcholine. The acetylcholinesterase inhibitor may be one or more selected from polyphenols, flavonoids, and organic acids, preferably one or more selected from malic acid, fumaric acid, and tocopherol.

The plants contain the neurotransmitters and/or the acetylcholinesterase inhibitors, and therefore, for example, eggplant, broccoli, banana, coconut, mandarin orange, herbs (coriander, cumin, sage, lemongrass, mugwort, comfrey, sage, shiso, lemon balm, oregano, catnip, common thyme, thyme, dill, dark opal, basil, hyssop, peppermint, spearmint, lamb's ear), dokudami, lavender, marigold, grapes, coffee (coffee plant), tea (camellia), cacao, acacia, cedar, pine, sugar cane, mango, banana, papaya, avocado, apple, cherry, etc. Lambo (cherry), guava, olive, potatoes (sweet potato, purple potato (sweet potato with a lot of purple pigment), potato, yam, taro (taro, shrimp potato, etc.), konjac, etc.), persimmon, mulberry, blueberry, poplar, ginkgo, chrysanthemum, sunflower, bamboo, citrus fruits (lemon, lime, orange, grapefruit, navel orange, yuzu, kumquat, kabosu, summer mandarin, hassaku, iyokan, lime, unshu mandarin, shikuwasa, mandarin, etc.), strawberry, blackberry, cranberry, raspberry, bilberry, huckleberry, plum, peach, plum, pear, European pear, loquat, kiwi fruit, mangosteen , Shishito peppers, prunes, melons, dragon fruit, wolfberries, black currants, cashews, viburnum, pomegranates, acai, aronia, tomatoes, soybeans, black soybeans, red beans, green beans, peanuts, black sesame, buckwheat, tartary buckwheat, sesame, purple cabbage, sumac, sumac tree, garland chrysanthemum, spinach, komatsuna, mitsuba, okra, butterbur, onions, mulukhiyah, garlic, purple onions, asparagus, parsley, eucalyptus, burdock, Gymnema sylvestre, senna, dandelions, horsetail, ferns (bracken, fern, etc.), oak, sawtooth oak, maple, sequoia, metasequoia, cypress, Mallotus japonicus, amacha, Akebia, Japanese angelica, Cleome, Japanese zelkova , Kobushi, Aralia arguta, Shiromoji, Kuromoji, Koshiabura, Kusagi, Magnolia obtusa, Actinidia japonica, Banaba, Rooibos, Rahma, Wolfberry, Kudzu, Megusrinoki, Liliana, Melbao, Aogiri, Suo, Brazilwood, Melinjo, Cherry, Magnolia, Yerba Mate, Candel, Bruguiera, Mangrove, Sea Pomegranate, Nipa Palm, Avicenna marina, Mangrove, Hermitage, Burdock, Turmeric, Lotus root, Shepherd's purse, pine, carrot, green pepper, chili pepper, paprika, bamboo, bamboo shoots, Japanese knotweed, cassava, bamboo grass, cloves, ginkgo, goldenrod, radish, mustard, etc., or processed products thereof. Among the above plants, eggplant, tomato, rosemary, bamboo grass, mint, eucalyptus, thyme, lemon balm, pine, coconut, bamboo, plum, chayote, lettuce, soybean, cassava, asparagus, mango, hibiscus, dandelion, horsetail, jolokia, and cacao are particularly suitable. The above plants may be parts of the plant body, such as stems, leaves, fruits, roots, seeds, husks, buds, flowers, and rhizomes. Two or more of these plants may also be used in combination.

The "plant extract" may be an extract obtained by extracting the plant with an appropriate extraction solvent, an extract liquid, or a dried or purified product thereof. In addition, the squeezed juice of the plant, its concentrate, dried product, purified product, etc. are also included in the "plant extract" since they contain the same components as the extract. The concentration of the plant extract is not particularly limited, but the solid mass ratio when applied to the plant can be, for example, 1.000 ppm to 100.000 ppm in the case of hydroponic cultivation, and preferably 10.000 ppm to 80.000 ppm.

The "extraction solvent" is preferably water, hot water, alcohol (particularly ethanol), aqueous alcohol (particularly aqueous ethanol), or petroleum ether, but is not limited to these.

The "dried material" is preferably one that has been processed by crushing, pulverizing, powdering, etc., and a powder with a small particle size is particularly preferable.

The "calcium ion" may be a water-soluble salt of calcium, and is not particularly limited as long as it exerts the effect of alleviating environmental stress or promoting growth of the plant of the present disclosure. The calcium ion may be, for example, an inorganic salt such as calcium sulfate or calcium chloride, or an organic acid salt such as calcium lactate, with calcium chloride being particularly preferred. The concentration of the calcium ion is not particularly limited, but the concentration when applied to the plant may be, for example, 0.001 mM to 100 mM in the case of hydroponic cultivation, and is preferably 0.01 mM to 10 mM, more preferably 0.1 mM to 1.0 mM, and particularly preferably 0.2 mM to 0.7 mM.

The environmental stress alleviator according to the present embodiment may contain, in addition to the plant extract and calcium ions, iron ions or other nutrients necessary for crop growth, other biostimulant materials, other plant growth promoters, fungicides, insecticides, plant hormones, etc., so long as they do not inhibit the plant environmental stress alleviation or growth promotion effects of the present disclosure.

The "iron ion" may be a water-soluble salt of iron(II) or iron(III), and is not particularly limited as long as it does not inhibit the plant environmental stress alleviation or growth promotion effect of the present disclosure. The iron ion may be, for example, iron chloride(II), iron chloride(III), iron sulfate(II), iron sulfate(III), etc., and iron chloride(II) is particularly preferred. The concentration of the iron ion is not particularly limited, but the concentration when applied to plants, for example, in hydroponic cultivation, may be 0.001 mM to 100 mM, preferably 0.01 mM to 10 mM, more preferably 0.1 mM to 1.0 mM, and particularly preferably 0.2 mM to 0.7 mM.

The "other nutrients necessary for crop growth" that may be contained in the environmental stress alleviator may be, for example, trace elements other than iron (boron, manganese, zinc, copper, molybdenum, etc.) or macronutrients (nitrogen, phosphate, potassium), and the aforementioned trace elements are preferred, but are not limited to these.

Plants to which the environmental stress relief agent of the present embodiment can be applied include, but are not limited to, vegetables such as leafy vegetables, fruit vegetables, root vegetables, and flower vegetables, grains such as rice and wheat, flowers, and fruit trees, and preferably lettuce, garland chrysanthemum, cabbage, spinach, tomato, eggplant, and paprika.

Next, a method for producing the environmental stress alleviator for plants according to the present embodiment will be described. The environmental stress alleviator for plants according to the present embodiment can be produced by mixing the plant extract and the calcium ions in the presence of water.

The plant extract can be obtained by extracting the plant using the extraction solvent. There are no particular limitations on the extraction conditions. After extraction, purification, concentration, drying, and other operations can also be performed.

The plant extract and the calcium ions are mixed in the presence of water. Here, "in the presence of water" refers to conditions under which the plant extract and the calcium ions can react with water as a medium. The amount of water is at least an amount that allows mixing and stirring of the plant extract and the calcium ions, and may be an amount that wets the mixture of the plant extract and the calcium ions. When using a liquid such as a squeezed juice or extract of a plant as the plant extract, or when using the calcium ions in the form of an aqueous solution, the two can be mixed directly without adding a new medium.

The mixing operation can be performed by simple stirring and mixing using a stirrer or the like, but can also be performed using a mixer, a large stirring tank, a vortex, a shaker, or the like. The temperature conditions during mixing are not particularly limited, and can be, for example, about room temperature (e.g., 10 to 35°C). The mixing time is not particularly limited, and can be until the plant extract and calcium ions are sufficiently in contact.

The plant environmental stress alleviator obtained in this manner is believed to have the function of switching on various stress resistance mechanisms inherent to plants, such as high temperature resistance, low temperature resistance, salt stress resistance, and oxidative stress resistance. Therefore, it is expected that the plant environmental stress alleviator according to this embodiment can be applied to plants to artificially control the plant's environmental stress resistance mechanism. For example, when plant cells are exposed to environmental stress such as high temperature, an influx of calcium ions from outside the cells is caused via ion channels. The plant environmental stress alleviator according to this embodiment activates calcium signal transduction within the cells by opening these ion channels, and is believed to endow the plant with environmental stress resistance. There are no particular limitations on the plants to which the environmental stress alleviator according to this embodiment can be applied.

The environmental stress alleviator of the present embodiment can promote plant growth under environmental stress by endowing the plant with environmental stress resistance. Therefore, the environmental stress alleviator of the present embodiment can also be called a plant growth promoter.

Next, a method of using the environmental stress alleviator of this embodiment will be described. The environmental stress alleviator of this embodiment can be used by applying an effective amount to a plant in the same manner as conventional fertilizers, plant growth promoters, and biostimulant materials. The effective amount may be an amount that exerts an environmental stress alleviation or plant growth promotion effect on the plant.

For example, in the case of hydroponic cultivation, a method of adding an appropriate amount of the environmental stress alleviator of this embodiment to the hydroponic solution is simple and preferable. Also, for example, the environmental stress alleviator of this embodiment may be sprayed or applied in an appropriate amount to the leaf surface of the plant. Also, for example, it can be irrigated into the soil in which the plant is growing, applied to seeds, or mixed with other agricultural materials such as liquid fertilizers, plant growth promoters, and biostimulant materials.

The amount and concentration of the environmental stress alleviator of this embodiment added to a hydroponic solution or other agricultural materials may be appropriately adjusted so that the concentrations of the plant extracts and calcium ions contained in the environmental stress alleviator are within the above-mentioned ranges, or so that the environmental stress alleviation or plant growth promotion effect on the plant is achieved. The timing and frequency of use of the environmental stress alleviator can be appropriately set according to the period when the crop is susceptible to environmental stress, and are not particularly limited.

The method of use of the environmental stress alleviator of this embodiment when used as a plant growth promoter is the same as described above.

The following describes this embodiment in more detail using examples.

(Test Example 1) High temperature resistance test using lettuce seedlings (part 1)
Many vegetables grown in Japan have low high-temperature tolerance. Lettuce is also adapted to relatively cool weather conditions, with the optimum temperature for growth being 18-23°C. When head lettuce is grown at high temperatures, abnormal heads such as oversized heads, small heads, bamboo shoot heads, and heads with protruding midribs are likely to occur, and physiological disorders (tip burn) caused by Ca deficiency are problematic. Conventionally, tests to confirm high-temperature tolerance of crops based on these symptoms took several months. Therefore, the inventors of the present application have developed a model experimental system to examine whether lettuce has acquired high-temperature tolerance through a two-week high-temperature cultivation test, taking advantage of the fact that high-temperature and long-day conditions induce the differentiation of flower buds and bolts and cause stem elongation in young lettuce plants.

(1) Preparation of environmental stress alleviators using eggplant residues The eggplant residues used were (a) 50 g of harvested eggplant flesh with the skin removed, (b) 20 g of sprouts removed during cultivation, (c) 20 g of harvested eggplant skin, and (d) 20 g of harvested eggplant roots. Each of these eggplant residues was placed in a 1-L beaker, to which 700 mL of distilled water was added, and the mixture was heated at 120°C for 20 minutes. The supernatant was then filtered through a filter paper, and the filtrate (eggplant residue extract) was mixed with boric acid (3 g), manganese sulfate (2 g), zinc sulfate (0.22 g), copper sulfate (0.05 g), sodium molybdate (0.01 g), ferrous sulfate (15 g), and calcium chloride (55 g), and further distilled water was added to obtain 1 L of each of the eggplant residue mixtures (a–d). In addition, eggplant residue mixed solutions (a' to d') containing no calcium ions were prepared as comparative examples in the same manner as above, except that calcium chloride was not added.

(2) Hydroponic cultivation test of lettuce seedlings 1 mL of each of the following nutrient solutions A to D was mixed with 1 mL of any of the eggplant residue mixtures (a to d, a' to d') prepared above, and distilled water was added to prepare 1 L of hydroponic solution. The amount of nutrient solution used to prepare each hydroponic solution (1 L) is shown in Table 1. The concentrations of calcium and trace elements in each hydroponic solution were 0.05 mM boric acid, 0.01 mM manganese sulfate, 0.001 mM zinc sulfate, 0.0003 mM copper sulfate, 0.0005 mM sodium molybdate, 0.1 mM ferrous sulfate, and 0.5 mM calcium chloride. The solids concentration of the eggplant residue extract in each hydroponic solution was 50,000 mg/L for flesh (a, a'), 20,000 mg/L for buds (b, b'), 20,000 mg/L for skin (c, c'), and 20,000 mg/L for roots (d, d').

Nutrient solution A: 700 mL of distilled water and 202 _{g of} KNO3 were placed in a 1 L beaker and stirred until dissolved, and further distilled water was added to make up to 1 L.
Nutrient solution B: 700 mL of distilled water and 178 g of KH ₂ PO ₄ were placed in a 1 L beaker and stirred until dissolved, and further distilled water was added to make up to 1 L.
Nutrient solution C: 700 mL of distilled water and 44 g of NH ₄ NO ₃ were placed in a 1 L beaker and stirred until dissolved, and further distilled water was added to make up to 1 L.
Nutrient solution D: 700 mL of distilled water and 489 g of MgSO ₄ · 7H ₂ O were placed in a 1 L beaker and stirred until dissolved, and further distilled water was added to make 1 L.

The prepared hydroponic solutions were placed in 1.2 L simple hydroponic cultivation devices, and lettuce seedlings (10 days after sowing) were planted and cultivated for 14 days under cultivation conditions of 12 h light/35°C, 12 h dark/25°C, and 60% humidity. As a control, hydroponic solutions prepared without adding the eggplant residue mixture (a-d, a'-d') were used. After 14 days of cultivation, the lettuce was harvested and the yield was measured.

(3) Results and Discussion The results are shown in Table 2. The values in Table 2 show the relative yield (%, fresh weight ratio) in each treatment plot when the yield in each control plot (nutrient solutions A to D only) is taken as 100%. Table 2 shows that the treatment plots using the hydroponic solution containing the eggplant residue extract and calcium ions (calcium chloride) had a significantly increased yield of 4 to 10.5 times compared to the comparative example treatment plot using a hydroponic solution without added calcium ions. These results show that the growth of lettuce seedlings is greatly promoted under high temperature conditions (25°C to 35°C) by cultivating them with the environmental stress alleviator of this embodiment added to the hydroponic solution, and high temperature stress resistance is imparted to them.

(Test Example 2) High temperature resistance test using lettuce seedlings (part 2)
Next, we investigated the effect of changing calcium concentration on mitigating high temperature stress.

(1) Preparation of environmental stress relief agent using eggplant residue As eggplant residue, 20g of sprouts removed during cultivation management of eggplant and 50g of fruit (with skin) after harvesting were used. Each of these eggplant residues was placed in a 1L beaker, 1000mL of distilled water was added thereto, and heated at 120°C for 20 minutes. The supernatant was then filtered through filter paper, and boric acid (3g), manganese sulfate (2g), zinc sulfate (0.22g), copper sulfate (0.05g), sodium molybdate (0.01g), ferrous sulfate (15g), calcium chloride (55g or 110g) were added to the filtrate (eggplant residue extract), and distilled water was further added to obtain 1L of eggplant sprout mixture and eggplant fruit mixture. In addition, eggplant sprout mixture and eggplant fruit mixture without calcium ion were prepared in the same manner as above except that calcium chloride was not added, and used as comparative examples.

(2) Hydroponic cultivation test of lettuce seedlings 1 mL of each of nutrient solutions A to D of Test Example 1 was mixed with 1 mL of either the eggplant sprout mixture or the eggplant fruit mixture prepared above, and distilled water was added to prepare 1 L of hydroponic solution. The amount of nutrient solution used to prepare each hydroponic solution (1 L) is shown in Table 3. The concentrations of calcium and trace elements in each hydroponic solution were 0.05 mM boric acid, 0.01 mM manganese sulfate, 0.001 mM zinc sulfate, 0.0003 mM copper sulfate, 0.0005 mM sodium molybdate, 0.1 mM ferrous sulfate, and 0.5 mM or 1.0 mM calcium chloride. The solids concentration of the eggplant residue extract in each hydroponic solution was 20.000 mg/L for sprouts and 50.000 mg/L for fruits.

The prepared hydroponic solutions were placed in 1.2 L simple hydroponic cultivation devices, and lettuce seedlings (10 days after sowing) were planted and cultivated for 14 days under cultivation conditions of 12 h light/35°C, 12 h dark/25°C, and 60% humidity. As a control, hydroponic solutions to which a specified amount of calcium chloride aqueous solution had been added were used instead of the eggplant sprout mixture and eggplant fruit mixture. After 14 days of cultivation, the lettuce was harvested and the yield was measured, and the Ca concentration in the plants was measured using an ICP emission spectrometer.

(3) Results and Discussion The results are shown in Table 4 and Figures 1A, 1B, 1C, 1D, and 1E. Figures 1A, 1B, and 1C are photographs showing the high temperature tolerance test, with Figure 1A showing the treatments with no calcium added, Figure 1B showing the treatments with 0.5 mM calcium, and Figure 1C showing the treatments with 1.0 mM calcium. Figure 2 shows the measured lettuce yield, and Figure 3 is a graph showing the relationship between lettuce yield and calcium concentration. The values in Table 4 and Figure 2 show the relative yield (%, fresh weight ratio) in each treatment when the yield in each control group is taken as 100%.

In Figure 1A (no calcium added), leaves in all treatments turned yellow, showing symptoms of calcium deficiency caused by high temperature damage, but in Figure 1B (0.5 mM calcium), high temperature damage was not observed in the treatments with eggplant residue extract compared to the control (untreated) without eggplant residue extract, and growth was clearly promoted. In Figure 1C (1.0 mM calcium), no leaf damage was observed in the control (untreated), but a clear growth promotion effect was observed in the treatments with eggplant residue extract.

Table 4 and Figure 2 show that the treatments using hydroponic solutions containing eggplant residue extract and calcium ions (calcium chloride) showed a large and significant increase in yield, 2 to 6.5 times, at all calcium ion concentrations, compared to the control areas using hydroponic solutions without added eggplant residue extract. In contrast, no significant difference was observed in the treatments without added calcium ions compared to the control areas (nutrient solutions A to D only). These results show that the growth of lettuce seedlings is greatly promoted under high temperature conditions (25°C to 35°C) by cultivating them in a hydroponic solution containing the environmental stress mitigating agent of this embodiment, and that high temperature stress resistance is imparted.

Figures 3 (B) and (C) show that calcium ion concentration increased in the treatment area where the environmental stress alleviator of this embodiment was applied. Furthermore, since the higher the calcium ion concentration in the plant, the higher the yield tends to be, suggesting that the increase in calcium ion concentration is related to the acquisition of high temperature resistance. As mentioned above, it is believed that the increase in calcium ion concentration within the cells switches on various stress resistance mechanisms in the plant. Therefore, it is speculated that the environmental stress alleviator of this embodiment has the effect of alleviating various environmental stresses other than high temperature stress.

Test Example 3 Comparison with Unutilized Biomass Other than Eggplant Residue Unutilized biomass other than eggplant residue was used to prepare the environmental stress alleviating agent of the present embodiment, and the effects were compared.

(1) Preparation of environmental stress alleviation agent Various crop residues shown in Table 5 below were used. The amount of each crop residue shown in Table 5 was placed in a 1L beaker, 700mL of distilled water was added, and the mixture was heated at 120°C for 20 minutes. The supernatant was then filtered through filter paper to obtain a filtrate (crop residue extract). Boric acid (3g), manganese sulfate (2g), zinc sulfate (0.22g), copper sulfate (0.05g), sodium molybdate (0.01g), ferrous sulfate (15g), calcium chloride (55g) were added to the filtrate, and distilled water was further added to obtain 1L of each crop residue mixture.

(2) Hydroponic cultivation test of lettuce seedlings 1 mL of each of the nutrient solutions A to D in Test Example 1 was mixed with 1 mL of any of the crop residue mixtures prepared above, and distilled water was added to prepare 1 L of hydroponic solution. The solid concentration of the crop residue extract in each hydroponic solution was 10,000 mg/L.

The prepared hydroponic solutions were placed in 1.2 L simple hydroponic cultivation vessels, and lettuce seedlings (10 days after sowing) were planted and cultivated for 14 days under cultivation conditions of 12 h light/35°C, 12 h dark/25°C, and 60% humidity. As a control, hydroponic solution to which 1 mL of 0.5 M calcium chloride aqueous solution was added instead of the crop residue mixture was used. As a comparative example, hydroponic solution to which humus (humic acid 0.3 g/L) and amino acids (glutamic acid 0.1 mM), which have been reported to have high temperature stress mitigating effects, were used instead of the crop residue mixture. After 14 days of cultivation, the lettuce was harvested and the yield was measured.

(3) Results and Discussion The results are shown in Table 6 and FIG. 4. The values in Table 6 and FIG. 4 show the relative yield (%, fresh weight ratio) in each treatment area when the yield in the control area is taken as 100%. Table 6 and FIG. 4 show that the treatment area using the hydroponic solution containing the crop residue extract and calcium ions (calcium chloride) had a significantly increased yield of 2 to 11 times compared to the control area using the hydroponic solution without the crop residue extract. In particular, the environmental stress relief agents using eggplant, tomato, rosemary, bamboo grass, mint, eucalyptus, thyme, lemon balm, pine, coconut, bamboo, plum, chayote, lettuce, soybean, cassava, asparagus, mango, hibiscus, dandelion, horsetail, jolokia, and cacao showed a remarkable effect compared to the humus and amino acids of the conventional technology. From these results, it was found that the environmental stress relief agent of the present embodiment can impart high temperature stress resistance to plants even when using plant extracts other than eggplant.

** As the conventional technology, humus (humic acid 0.3 g/L) and amino acids (glutamic acid 0.1 mM) were used.

(Test Example 4) High temperature stress reduction effect by standard substance It is considered that the plant environmental stress mitigating agent of this embodiment can activate intracellular Ca signal transduction and provide environmental stress resistance to the plant. In addition, Test Example 2 suggested that there is a correlation between improved high temperature resistance and increased Ca concentration in the plant. Therefore, in this test example, the purpose was to help elucidate the mechanism of the present disclosure by investigating the environmental stress reduction effect when a standard substance known as a neurotransmitter or acetylcholinesterase inhibitor that causes the influx of Ca ions into cells was used together with calcium ions.

(1) Test method 20 g of each of the standard substances shown in Figure 5 was taken, and boric acid (3 g), manganese sulfate (2 g), zinc sulfate (0.22 g), copper sulfate (0.05 g), sodium molybdate (0.01 g), ferrous sulfate (15 g), and calcium chloride (55 g) were added thereto, and distilled water was further added thereto to obtain 1 L of each standard substance mixture. Next, 1 mL of each of the nutrient solutions A to D of Test Example 1 was combined with 1 mL of any of the standard substance mixtures prepared above, and distilled water was further added to prepare 1 L of hydroponic solution. The prepared hydroponic solutions were each placed in a 1.2 L simple hydroponic cultivation vessel, and lettuce seedlings (10 days after sowing) were planted and cultivated for 14 days under cultivation conditions of 12 h light/35°C, 12 h dark/25°C, and 60% humidity. As a control (untreated), hydroponic solution to which 1 mL of 0.5 M calcium chloride aqueous solution was added instead of the standard substance mixture was used. As a comparative example, hydroponic solutions containing GABA (final concentration 0.516 g/L), humic acid (final concentration 0.3 g/L), and alanine (final concentration 0.5 g/L), which have been reported to alleviate high temperature stress, were used instead of the standard substance. After 14 days of cultivation, the lettuce was harvested and the yield was measured.

(2) Results and Discussion The results are shown in FIG. 5. The values in FIG. 5 represent the relative yield (%, fresh weight ratio) in each treatment area when the yield in the control area (untreated) is taken as 100%. FIG. 5 shows that the treatment areas using malic acid, fumaric acid, acetylcholine, tocopherol, and succinic acid had a significantly increased yield compared to the control area and the treatment areas of the comparative example. Acetylcholine is a neurotransmitter known to be contained in many plants, and malic acid, fumaric acid, and tocopherol are all acetylcholinesterase inhibitors contained in plants. This result suggests that it is highly likely that these acetylcholine and acetylcholinesterase inhibitors act as active ingredients in the environmental stress relief agent of this embodiment.

As shown in the above examples, by applying to a plant an environmental stress alleviator containing the plant extract and calcium ions according to the present disclosure, it is possible to endow the plant with resistance to environmental stress while maintaining a sufficient growth-promoting effect. In addition, the environmental stress alleviator according to the present disclosure can utilize unused biomass such as crop residues generated in agriculture and waste from food processing plants as raw materials. Therefore, the present disclosure can be used in the agricultural and food processing industries.

Claims (8)

Contains plant extracts and calcium ions ,
The agent for alleviating environmental stress for plants, wherein the plant extract is an extract of one or more plants selected from the group consisting of eggplant, tomato, rosemary, bamboo grass, mint, eucalyptus, thyme, lemon balm, pine, coconut, bamboo, plum, chayote, lettuce, soybean, cassava, asparagus, mango, hibiscus, dandelion, horsetail, jolokia, and cacao, and contains acetylcholine or one or more acetylcholinesterase inhibitors selected from polyphenols, flavonoids, and organic acids. The environmental stress alleviation agent for plants according to claim 1, further comprising iron ions and trace elements. The environmental stress alleviator for plants according to claim 1, containing calcium ions at a concentration of 0.001 mM to 100 mM when applied to plants. The environmental stress alleviation agent for plants according to claim 1, which is used by adding it to a hydroponic solution. The environmental stress alleviating agent for plants according to claim 1, which is applied to one or more plants selected from lettuce, garland chrysanthemum, cabbage, spinach, tomato, and eggplant. Contains plant extracts and calcium ions ,
The plant growth promoter is an extract of one or more plants selected from the group consisting of eggplant, tomato, rosemary, bamboo grass, mint, eucalyptus, thyme, lemon balm, pine, coconut, bamboo, plum, chayote, lettuce, soybean, cassava, asparagus, mango, hibiscus, dandelion, horsetail, jolokia, and cacao, and contains acetylcholine or one or more acetylcholinesterase inhibitors selected from polyphenols, flavonoids, and organic acids. A method for alleviating environmental stress in a plant, comprising applying the agent for alleviating environmental stress for a plant according to any one of claims 1 to 5 to the plant. A method for promoting plant growth, which comprises applying the plant growth-promoting agent according to claim 6 to a plant.