Method for raising gramineous plant

Abstract

To provide a method for raising gramineous plant which suppresses insect damage by fall armyworms and is capable of safely and suitably raising the gramineous plant.SOLUTION: Light whose center wavelength is within a range of 380 nm to 550 nm is irradiated to a gramineous plant during the night to suppress movement of fall armyworms.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a method for growing grass plants while controlling armyworm. [Background technology]

[0002] Grass plants such as rice, wheat, and corn are important not only as food crops but also as forage crops. In recent years, the habitat of the fall armyworm (a noctuid moth) has expanded, and damage to grasses such as feed corn, sorghum, sugarcane, oats, Job's tears, waxy millet, and pasture grasses has been confirmed in Japan. This damage is caused by feeding damage by fall armyworm larvae, which tend to feed on the tender leaves of grasses in the early stages of growth. Plants damaged by the larvae can wither and die, causing severe damage to the growth of grasses, and therefore research into how to control fall armyworm is ongoing.

[0003] Known methods for growing grasses while controlling fall armyworm include, for example, a method using an insecticide (pesticide) containing a specific compound that is effective in controlling fall armyworm (see Patent Document 1), and a method using a transgenic grasses and its seeds that express an insecticidal protein having a specific amino acid sequence that is effective in controlling fall armyworm using gene transformation technology (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2020-531551 (pages 7 to 10) [Patent Document 2] Special Publication No. 2022-501035 (pages 9 to 10) Summary of the Invention [Problem to be solved by the invention]

[0005] However, although the insecticides and insecticidal proteins used in Patent Documents 1 and 2 are expected to have a temporary control effect against the armyworm, there is a risk that the control effect will be weakened if the armyworm acquires resistance to these insecticides or insecticidal proteins. Furthermore, since the insecticides and insecticidal proteins may affect the growth of grass plants and the surrounding environment, a method is desired that can suppress feeding damage by the armyworm and enable the safe and suitable growth of grass plants.

[0006] The present invention has been made in light of these problems, and an object of the present invention is to provide a method for growing grasses that can suppress feeding damage caused by the armyworm and enable grasses to be grown safely and suitably. [Means for solving the problem]

[0007] In order to solve the above problems, the method for growing a grass plant of the present invention comprises: The method is characterized by irradiating grass plants with light having a central wavelength in the range of 380nm to 550nm at night, thereby suppressing the behavior of the armyworm. According to this feature, by irradiating grass plants at night with light having a central wavelength in the range of 380 nm to 550 nm, the behavior of the armyworm can be suppressed without affecting the growth of the grass plants, and the hatching rate of the larvae can be reduced, thereby suppressing damage to the grass plants, allowing the grass plants to be grown safely and favorably.

[0008] The light has a central wavelength in the range of 465 to 475 nm. According to this feature, by irradiating light with a central wavelength in the range of 465 to 475 nm at night, it is possible to effectively suppress the behavior of male armyworm moths and their mating behavior, which is greatly influenced by male behavior, without affecting the growth of grasses.

[0009] The light has a central wavelength in the range of 515 to 525 nm. According to this feature, by irradiating grass plants at night with light having a central wavelength in the range of 515 to 525 nm, it is possible to effectively suppress the behavior of female armyworms, and to effectively suppress mating and egg-laying behavior due to female behavior, without affecting the growth of grass plants.

[0010] The light has a central wavelength in the range of 465 to 475 nm and in the range of 515 to 525 nm. According to this feature, by irradiating light with central wavelengths in the range of 465 to 475 nm and 515 to 525 nm at night, it is possible to effectively suppress the behavior of both male and female armyworms, i.e., mating behavior and oviposition behavior, and reduce the hatching rate of larvae without affecting the growth of grasses.

[0011] The grass plant is characterized in that it is maize. According to this feature, corn is less susceptible to the effects of nighttime irradiation with light having a central wavelength in the range of 380 nm to 550 nm, and can be grown favorably.

[0012] The corn is characterized by being in the 2 to 8 leaf stage. According to this feature, the behavior of the armyworm is suppressed during the 2- to 8-leaf stage when feeding damage by the armyworm larvae is likely to lead to serious damage such as withering and death, thereby reducing the hatching rate of the larvae and enabling favorable growth of corn without affecting its growth during the early 2- to 8-leaf stage.

[0013] The nighttime period is characterized by the time period from sunset to late night. According to this feature, by shortening the time of nighttime illumination, it is possible to reduce the cost of nighttime illumination while suppressing the behavior of the armyworm.

[0014] The light is irradiated from above the grass plant. This feature allows light emitted at night to more easily reach the growing points of grass plants, where female armyworms tend to gather to lay eggs, thereby efficiently suppressing the egg-laying behavior of female armyworms. [Brief explanation of the drawings]

[0015] [Figure 1] (a) is a graph showing the irradiance of four color (blue, green, yellow, red) LEDs in indoor experiment 1, and (b) is a graph showing the photon flux density (PFD) of the same LEDs. [Figure 2] (a) is a graph showing the number of reactions of adult male armyworms to nighttime illumination of four-color LEDs (days 1 to 5) in laboratory experiment 1, and (b) is a graph showing the number of reactions of adult female armyworms. [Figure 3] (a) is a graph showing the cumulative number of reactions of adult male armyworms to nighttime illumination of four-color LEDs (days 3 to 5) in laboratory experiment 1, and (b) is a graph showing the cumulative number of reactions of adult female armyworms. [Figure 4] (a) is a graph showing the mating rate in the area exposed to blue LEDs at night (n=9) and in the area without illumination (n=8) in indoor experiment 2, and (b) is a graph showing the number of eggs laid in the area exposed to blue LEDs at night and in the area without illumination. [Figure 5] (a) is a graph showing the change in the number of armyworm larvae (number of noctuid moth larvae / plant) in response to nighttime illumination using blue and green LED irradiation devices in field experiment 1, and (b) is a graph showing the damage to the leaves of feed corn. [Figure 6] Graph (a) shows the results of the growth survey (leaf stage) of feed corn in field experiment 1, and graph (b) shows the results of the growth survey (plant height). [Figure 7](a) is a graph showing the change in the number of armyworm larvae (number of noctuid larvae / plant) in response to nighttime irradiation (short-term irradiation, long-term irradiation) using blue and green LED irradiation devices in field experiment 2, and (b) is a graph showing the damage to the leaves of feed corn. [Figure 8] Graph (a) shows the results of the growth survey (leaf stage) of feed corn in field experiment 2, and graph (b) shows the results of the growth survey (plant height). [Figure 9] (a) is a graph showing the number of armyworm larvae (number of noctuid moth larvae / plant) in response to nighttime illumination with a blue LED irradiation device 17 days after sowing of feed corn seeds in field experiment 3, and (b) is a graph showing the number of armyworm larvae (number of noctuid moth larvae / plant) 25 days after sowing. [Figure 10] 1 is a graph showing damage to the leaves of feed corn in field experiment 3. [Figure 11] Graph (a) shows the results of the growth survey (leaf stage) of feed corn in field experiment 3, and graph (b) shows the results of the growth survey (plant height). DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described. However, the present invention can be embodied in many different forms and is not limited to the following embodiments and examples.

[0017] The method for cultivating a grass plant according to this embodiment (hereinafter sometimes referred to as "the present cultivation method") suppresses the behavior of the armyworm, specifically its mating behavior and egg-laying behavior, and reduces the hatching rate of the larvae, thereby suppressing damage to the grass plant, without affecting the growth of the grass plant, by irradiating the grass plant with light having a central wavelength in the range of 380 nm to 550 nm at night, thereby enabling the safe and suitable cultivation of the grass plant.

[0018] Furthermore, in the present cultivation method, it is preferable to irradiate the grass plant at night with light having a central wavelength in the range of 465 to 475 nm, preferably in the range of 467 to 473 nm, and more preferably in the range of 469 to 471 nm, which can effectively suppress the behavior of male armyworms and mating behavior, which is significantly influenced by male behavior, without affecting the growth of the grass plant.

[0019] Furthermore, in the present cultivation method, it is preferable to irradiate the grass plant at night with light having a central wavelength in the range of 515 to 525 nm, preferably in the range of 517 to 523 nm, and more preferably in the range of 519 to 521 nm, which can effectively suppress the behavior of female armyworms and effectively suppress mating and egg-laying due to female behavior without affecting the growth of the grass plant.

[0020] Furthermore, in this cultivation method, it is more preferable to irradiate the grass plant with light having a central wavelength in the range of 465 to 475 nm and in the range of 515 to 525 nm at night, which can effectively suppress the behavior of both male and female armyworms, i.e., mating behavior and oviposition behavior, and reduce the hatching rate of larvae, without affecting the growth of the grass plant.

[0021] The light having a central wavelength in the range of 465 to 475 nm and the light having a central wavelength in the range of 515 to 525 nm may be obtained by combining a light source that irradiates light having a central wavelength in the range of 465 to 475 nm with a light source that irradiates light having a central wavelength in the range of 515 to 525 nm, or light irradiated from a single light source may have two peaks in the ranges of 465 to 475 nm and 515 to 525 nm. Furthermore, in the wavelength characteristics of the light irradiated at night in this growth method, the half-width is preferably about 30 to 100 nm. Furthermore, it does not matter which of the peak intensities in the range of 465 to 475 nm and the range of 515 to 525 nm is stronger.

[0022] Furthermore, the grass plant to which this cultivation method is applied is preferably corn, which is less susceptible to nighttime irradiation with light having a central wavelength in the range of 380 nm to 550 nm, and more preferably corn in the 2- to 8-leaf stage, which is more susceptible to feeding damage by larvae and can lead to serious damage such as withering.

[0023] Furthermore, the time period during which nighttime irradiation with light having a central wavelength in the range of 515 to 525 nm is preferably from sunset to late at night. By shortening the time of nighttime irradiation, the cost of nighttime irradiation can be reduced while suppressing the behavior of the armyworm. Specifically, by irradiating light having a central wavelength in the range of 515 to 525 nm for a short period of time only from sunset to late at night, the oviposition behavior of female armyworms can be effectively suppressed, resulting in a reduction in the number of armyworm larvae and suppression of damage to grass plant leaves. Note that "late at night" refers to the time period between 11:00 PM and 1:00 AM.

[0024] Furthermore, in this cultivation method, it is preferable to irradiate the grasses with light from above, which makes it easier for the irradiated light to reach the growing points of the grasses where female armyworm moths tend to gather to lay eggs, thereby efficiently suppressing the egg-laying behavior of the females.

[0025] Furthermore, in this cultivation method, the light source for irradiating grass plants at night preferably has a luminous intensity of 15,000 to 25,000 mcd for light sources with a central wavelength in the range of 465 to 475 nm, and a luminous intensity of 40,000 to 50,000 mcd for light sources with a central wavelength in the range of 515 to 525 nm. This ensures that the illuminance of light reaching the vicinity of the growth point of grass plants from a light source installed at a height of 50 to 100 cm above the ground is sufficient, thereby achieving the effect of suppressing the behavior of the armyworm. [Example]

[0026] Here, as a preliminary experiment for carrying out the method for growing a grass plant according to the embodiment of the present invention, an experiment for confirming the wavelength of light effective in suppressing the behavior of armyworm will be specifically described below.

[0027] (Indoor experiment 1) In laboratory experiment 1, one adult male or female of the armyworm was placed in a bottle placed in a breeding box that was shielded from external light, and the insects were illuminated with a blue LED (OptoSupply, OSB56A5111A (center wavelength 470 nm, half width 22 nm, luminous intensity 20,000 mcd)) and a green LED (OptoSupply, OSG58A5111A (center wavelength 525 nm, half width 38 nm, luminous intensity 45,000 mcd)). )), yellow LED (OptoSupply, OS5YKA5111A (center wavelength 590nm, half width 20nm, luminous intensity 50,000mcd)), and red LED (OptoSupply, OSG58A5111A (center wavelength 660nm, half width 22nm, luminous intensity 14,400mcd)) were used at night to investigate the wavelengths that are effective in suppressing the behavior of the armyworm.

[0028] The wavelength characteristics of the four color LEDs used in Indoor Experiment 1 are shown in Figure 1. In Figure 1, the wavelength characteristics of the blue LED are shown by a solid line, the wavelength characteristics of the green LED by a dashed line, the wavelength characteristics of the yellow LED by a one-dot chain line, and the wavelength characteristics of the red LED by a two-dot chain line. A spectroradiometer (KONICA MINOLTA, CL-500A) was used to measure the wavelength characteristics, and measurements were taken under the following conditions: the thickness of the spectroradiometer sensor, i.e., the height from the bottom of the container, was 85 mm; the distance from the bottom of the container to the LED was 225 mm; and the distance from the LED to the spectroradiometer sensor was 140 mm.

[0029] As shown in Figure 1(a), the total irradiance of the blue LED is 11.3 Wm -2 , the total irradiance of the green LED is 5.6 Wm -2 , the total irradiance of the yellow LED is 2.5Wm -2 The total irradiance of the red LED is 3.9 Wm -2As shown in Figure 1(b), the total photon flux density of the blue LED was 44.7 μmol m -2 ·s -1 , the total photon flux density for the green LED is 24.6 μmol m -2 ·s -1 The total photon flux density for the yellow LED is 12.4 μmol m -2 ·s -1 The total photon flux density for the red LED is 21.1 μmol m -2 ·s -1 It was.

[0030] In Laboratory Experiment 1, fluorescent lights were turned on instead of daylight during the daytime hours from 8:00 AM to 8:00 PM, and during the nighttime hours from 8:00 PM to 8:00 AM (hereinafter sometimes referred to as the "dark period"), one of the four colors of LEDs mentioned above was turned on, and an infrared sensor was shone horizontally toward the bottle, automatically recording the number of times the armyworm crossed the area irradiated by the infrared sensor. In the control experiment, which had no illumination, fluorescent lights were turned on in the same way during the daytime hours from 8:00 AM to 8:00 PM, but were turned off during the nighttime hours (dark period) from 8:00 PM to 8:00 AM.

[0031] (result) The number of times (number of responses) that male or female armyworms crossed the area illuminated by the infrared sensor during the dark period from day 1 to day 5 in Laboratory Experiment 1 was recorded and the results are shown in Figure 2. The cumulative number of responses during the dark period from day 3 to day 5 is shown in Figure 3.

[0032] As shown in Figure 2(a), the number of reactions by males of the armyworm moth was lowest under blue light, ranging from 0 to several times, followed by green light, which fluctuated less than approximately 40 times, yellow light, which fluctuated less than approximately 70 times, and red light, which was highest, fluctuating less than approximately 180 times.

[0033] Furthermore, as shown in Figure 3(a), the cumulative number of reactions of males of the armyworm during the dark period from the third to fifth day was lowest under blue light (a few times), highest under green light (approximately 90 times), yellow light (approximately 110 times), and red light (approximately 520 times).

[0034] In other words, it was confirmed that the behavioral inhibitory effect of males of the armyworm moth was highest in the following order: blue light > green light ≒ yellow light > red light.

[0035] Furthermore, as shown in Figure 2(b), the number of reactions by female armyworms was lowest under green light, at approximately 30 times or less, followed by blue light at approximately 50 times or less, red light at approximately 70 times or less, and yellow light at approximately 180 times or less.

[0036] Furthermore, as shown in Figure 3(b), the cumulative number of reactions of female armyworms during the dark period from the third to fifth day was lowest under green light at approximately 40 times, highest under blue light at approximately 70 times, red light at approximately 130 times, and yellow light at approximately 370 times.

[0037] In other words, it was confirmed that the behavioral inhibitory effect of female armyworms was highest in the order green light > blue light > red light > yellow light.

[0038] The results of Laboratory Experiment 1 confirmed that blue and green light are effective in suppressing the behavior of the armyworm, while yellow and red light are not.

[0039] These results confirmed that light with a central wavelength in the range of 380 nm to 550 nm, excluding yellow and red light, is effective in suppressing the behavior of the armyworm.

[0040] (Indoor experiment 2) In Laboratory Experiment 2, pairs of virgin adult male and female Spodoptera moths were placed in a jar placed in a light-blocking rearing box and irradiated overnight using a blue LED (OptoSupply, OSB56A5111A, central wavelength 470 nm, full width at half maximum 22 nm, luminous intensity 20,000 mcd). Three days later, the female spermatheca was dissected and the number of spermatophores counted to calculate mating rates. The number of egg masses laid in the glass jar was also counted to investigate the effectiveness of blue light in inhibiting mating and oviposition in Spodoptera moths. The irradiation conditions, such as irradiation time, for the blue LED irradiation area and the unirradiated control area were the same as those for Laboratory Experiment 1.

[0041] (result) As shown in Figure 4(a), the mating rate in indoor experiment 2 was 11.1% (1 / 9 pairs) in the blue LED irradiation area, which was significantly lower than the 62.5% (5 / 8 pairs) in the non-irradiation area.

[0042] Furthermore, as shown in Figure 4(b), the number of eggs (egg masses) laid in indoor experiment 2 was 0 in the blue LED irradiation area, which was significantly lower than the 1.4 in the non-irradiation area.

[0043] These results confirmed that blue light irradiation inhibits mating and reduces egg production in the armyworm. In other words, light with a central wavelength in the range of 380 nm to 550 nm was found to be effective in inhibiting mating and egg production in the armyworm.

[0044] Next, based on the results of the above-mentioned indoor experiments 1 and 2, an experiment was conducted in a field of feed corn, a grass plant, to confirm the effect of suppressing the behavior of the armyworm moth by irradiating it at night using a blue (center wavelength 470 nm) or green (center wavelength 525 nm) LED irradiation device.

[0045] (Field experiment 1) We released the armyworm (unmated adults) into a greenhouse where feed corn (Kaneko Seed, KD731) was grown, and investigated the behavioral suppression effect of the armyworm by irradiating it at night with blue (center wavelength 470 nm) or green (center wavelength 525 nm) LEDs.

[0046] In field experiment 1, nighttime illumination using a blue or green LED was performed from 6:00 PM to 6:00 AM every day from four days after sowing feed corn seeds in the soil in the greenhouse until the end of the study. Hereinafter, the illumination time was set to completely cover the dark period during the experiment.

[0047] In field experiment 1, virgin adult S. fallopia moths (9 males and 9 females) were released into a greenhouse 13 days after sowing of feed corn seeds. The number of S. fallopia moth larvae was counted 2 days (15 days after sowing), 5 days (18 days after sowing), 12 days (25 days after sowing), 19 days (32 days after sowing), and 29 days (42 days after sowing) after the release of the virgin adult S. fallopia moths.

[0048] The life cycle of the armyworm is as follows: egg stage lasts 2-3 days, 1st to 6th instar larvae last 14 days, pupal stage lasts 8-9 days, and adult lifespan of females is 15-21 days, making one generation about 30 days.

[0049] In addition, the growth of the feed corn (leaf stage and plant height) was investigated 28 days after sowing, and the damage to the leaves of the feed corn was investigated 44 days after sowing.

[0050] Regarding the assessment of the degree of damage, damage level 1 is a state in which there are no damage marks on the leaves, or only slight pinhole-shaped damage marks are seen on the lower leaves; damage level 2 is a state in which pinhole-shaped holes or small circular holes are observed on multiple leaves, or damage marks are seen on the leaves being extracted but are 1.3 cm or less in length; damage level 3 is a state in which eight or more leaves (or more than half) have damage marks 2.5 cm or more in length, and small to medium-sized irregular holes are seen on the leaves being extracted, but no damage marks longer than 2.5 cm are seen; damage level 4 is a state in which most of the upper leaves have numerous damage marks significantly longer than 2.5 cm in length, and numerous irregular holes are observed on the leaves being extracted; and damage level 5 is a state in which the leaves have been damaged to the extent that the plant body has withered and died.

[0051] The LED irradiation device uses multiple LEDs identical to those used in the above-mentioned indoor experiments 1 and 2, and is capable of irradiating light in a 360-degree direction from a light source unit installed 50 to 100 cm above the ground.

[0052] In addition, in Field Experiment 1, the greenhouse installation area was 9.9 m 2 Three greenhouses will be set up, each illuminated with blue light, three with green light, three with no treatment (control greenhouse), and three greenhouses without the release of armyworms.

[0053] (result) Figure 5 shows the density of fall armyworm larvae (number of noctuid larvae / plant) and the extent of damage in Field Experiment 1. As shown in Figure 5(a), fall armyworm larvae density was lowest in the order of untreated (C) > green (G) > blue (B) > non-released (N), with the exception of non-released (N) where blue light was irradiated at night (below, results are explained excluding non-released (N) where necessary). Although fall armyworm larvae temporarily appeared in the non-released (N) case, these are presumed to be fall armyworm larvae that had naturally appeared in the greenhouse.

[0054] Furthermore, as shown in Figure 5(b), the damage to the leaves of feed corn was evaluated on a five-point scale, with the results being untreated (C) > green (G) > blue (B) > no-grazing (N), and the damage was least when blue light was irradiated at night.

[0055] The growth status of feed corn is shown in Figure 6. As shown in Figure 6(a), the leaf stage of 10 plants randomly selected 28 days after sowing was between 5 and 6 leaves, and it was confirmed that there was no significant difference between the treatments.

[0056] Furthermore, as shown in Figure 6(b), plant height was approximately 22 to 28 cm, and no significant difference was observed between the treatments. In other words, it was confirmed that the nighttime illumination in this experiment did not adversely affect the growth of feed corn.

[0057] (Field experiment 2) Next, we investigated the effects of different lighting durations of blue (center wavelength 470 nm) or green (center wavelength 525 nm) LED lighting devices during the dark period. Regarding the experimental method for Field Experiment 2, the same configuration as that of Field Experiment 1 described above will not be explained here.

[0058] In field experiment 2, the period from six days after planting plug seedlings of feed corn (Kaneko Seed, KD731) in the soil in a greenhouse until the end of the survey was conducted under two conditions: "long-term lighting," in which night-time illumination was provided by blue or green LED illumination devices from 7:00 PM to 5:00 AM every day; and "short-term lighting," in which night-time illumination was provided by blue or green LED illumination devices from 7:00 PM to 11:00 PM, in other words, from sunset to midnight.

[0059] Note that the above-mentioned Field Experiment 1 was conducted in April and May, which means that the dark period is long, and therefore the irradiation time was set to a long 12 hours. However, Field Experiment 2 was conducted in June and July, which means that the dark period is shorter than in April and May, and therefore the irradiation time under "long lighting" was set to a short 10 hours.

[0060] In field experiment 2, virgin adult S. fallopia moths (10 males and 10 females) were released into the greenhouse 7 days after planting the feed corn seedlings. The number of S. fallopia moth larvae was counted the day before (6 days after planting), 8 days after (15 days after planting), 20 days after (27 days after planting), and 27 days after (34 days after planting). In field experiment 2, because almost noctuid moths, including S. fallopia moths, were found in the greenhouse 8 days after the release of virgin adult S. fallopia moths, additional virgin adult S. fallopia moths (8 males and 8 females) were released.

[0061] In addition, the growth of the feed corn (leaf stage and plant height) was investigated 27 days after planting, and the damage to the leaves of the feed corn was investigated 34 days after planting.

[0062] (result) The density of armyworm larvae (number of noctuid larvae / plant) and the damage situation are shown in Figure 7. As shown in Figure 7(a), the density of armyworm larvae was lower when blue or green light was irradiated for a long period at night than when blue or green light was irradiated for a short period at night, as shown in Figure 7(a).

[0063] Furthermore, as shown in Figure 7(b), damage to the leaves of feed corn was evaluated on a five-point scale, resulting in the following: untreated (C) > blue short-time (BS) > green short-time (GS) > green long-time (GL) ≒ blue long-time (BL) > no-grazing (N), meaning that damage was reduced when blue or green light was irradiated for long periods at night. Furthermore, the proportion of damage level 4 was lower in blue short-time (BS), and the proportion of damage level 1 was higher in green short-time (GS) than in blue short-time (BS), and the combined proportion of damage levels 3 and 4 was lower, so the ranking was blue short-time (BS) > green short-time (GS).

[0064] Furthermore, when blue or green light was irradiated for a short time at night, the proportion of damage level 1 was higher under short-duration green light (GS) than under short-duration blue light (BS), resulting in less damage. This result is presumably due to a reduction in the number of larvae caused by the suppression of female armyworm oviposition behavior.

[0065] The growth status of feed corn is shown in Figure 8. As shown in Figure 8(a), the leaf stage of 10 plants randomly selected 28 days after planting was 6 to 7 leaves, and it was confirmed that there was no significant difference between the treatments.

[0066] Furthermore, as shown in Figure 8(b), the plant height was approximately 50-60 cm, and no significant difference was observed between the treatments. In other words, it was confirmed that the short-term and long-term nighttime illumination in this experiment did not adversely affect the growth of feed corn.

[0067] (Field experiment 3) Next, we investigated the effects of blue LED irradiation (center wavelength 470 nm) during the dark period on outdoor-grown feed corn (Kaneko Seeds, NS118 Super). Note that the experimental method for Field Experiment 3 was the same as that for Field Experiments 1 and 2, so a description of the experimental setup will be omitted.

[0068] In field experiment 3, we investigated the behavioral suppression effect of the fall armyworm by irradiating the soil with blue LED light from 6:00 p.m. to 6:00 a.m. every day from six days after sowing feed corn seeds until the end of the study.

[0069] In field experiment 3, nighttime illumination using a blue LED irradiation device was carried out from 6 p.m. to 6 a.m. every day from six days after sowing feed corn seeds to the end of the study. The blue light LED irradiation area and the untreated control area were set up in three areas evenly distributed across the field.

[0070] Surveys of the number of armyworm moth larvae were conducted 17 days after sowing and 25 days after sowing, and the number of armyworm moth larvae was surveyed within a radius of 0 to 5 m and within a radius of 5 to 10 m from the LED irradiation device.

[0071] In addition, damage and growth of the feed corn (leaf stage and plant height) were investigated 25 days after sowing.

[0072] (result) The density of fall armyworm larvae (number of noctuid moth larvae per plant) and the extent of damage are shown in Figure 9. As shown in Figure 9(a), in the area exposed to blue light LEDs, the density of fall armyworm larvae 17 days after sowing averaged 1.1 larvae per plant within a radius of 0 to 5 m, and 2.4 larvae within a radius of 5 to 10 m. In the untreated area, the density of fall armyworm larvae 17 days after sowing averaged 2.7 larvae per plant within a radius of 0 to 5 m, and 2.6 larvae within a radius of 5 to 10 m.

[0073] In other words, 17 days after sowing, the density of armyworm larvae was untreated (0-5m) ≒ untreated (5-10m) ≒ blue (5-10m) > blue (0-5m), and when blue light was irradiated at night, the behavioral suppression effect of the armyworm was confirmed within a radius of 0-5m from the LED irradiation device.

[0074] The reason why the density of armyworm larvae within a 5- to 10-m radius of the LED irradiation device was the same as that in the untreated area is presumably because the illuminance of blue light suddenly decreased within a 3- to 4-m radius of the LED irradiation device used in Field Experiment 3, so that the blue light was not irradiated with sufficient illuminance within a 5- to 10-m radius, and therefore the behavioral suppression effect of the armyworm was not achieved.

[0075] Furthermore, as shown in Figure 9(b), in the blue light LED irradiation area, the density of fall armyworm larvae 25 days after sowing was an average of 2.0 individuals / plant within a radius of 0-5 m and an average of 1.9 individuals / plant within a radius of 5-10 m. In the untreated control area, the density of fall armyworm larvae 25 days after sowing was an average of 2.5 individuals / plant within a radius of 0-5 m and an average of 2.0 individuals / plant within a radius of 5-10 m. In other words, the density of fall armyworm larvae 25 days after sowing was equivalent in both the untreated (0-5 m) and untreated (5-10 m) areas, respectively, and the blue (5-10 m) and blue (0-5 m) areas.

[0076] The reason why the density of armyworm larvae in the 0-5 m radius range and the 5-10 m radius range in the blue light LED irradiation area was the same is presumably because the armyworm larvae that emerged in the 5-10 m radius range in the blue light LED irradiation area and in the untreated area dispersed and invaded the 0-5 m radius range in the blue light LED irradiation area.

[0077] Furthermore, as shown in Figure 10, the damage to the leaves of feed corn was evaluated on a 5-point scale, with the results being untreated (0-5 m) ≒ untreated (5-10 m) ≒ blue (5-10 m) > blue (0-5 m), meaning that damage was less within a radius of 0-5 m in the area irradiated with blue light LEDs.

[0078] The growth status of feed corn is also shown in Figure 11. As shown in Figure 11(a), the leaf stage of 10 plants randomly selected 25 days after sowing was 8 leaves in the area of ​​0 to 5 m radius in the blue light LED irradiation area and the untreated area, the area of ​​5 to 10 m radius in the blue light LED irradiation area and the untreated area, and the area of ​​0 to 10 m radius in the blue light LED irradiation area and the untreated area (all areas), confirming that there was no significant difference between the treatments.

[0079] Furthermore, as shown in Figure 11(b), plant height was approximately 55 cm in the 0-5 m radius range in the blue light LED irradiation area and the untreated area, the 5-10 m radius range in the blue light LED irradiation area and the untreated area, and the 0-10 m radius range in the blue light LED irradiation area and the untreated area (all areas), confirming that there was no significant difference between the treatments. In other words, it was confirmed that the nighttime illumination in this experiment did not have a negative impact on the growth of feed corn.

[0080] As described above, the results of field experiments 1 to 3 indicate that by irradiating the entire field with blue and green light of sufficient intensity at night, it is possible to suppress the behavior of the armyworm throughout the field without affecting the growth of feed corn, and this can reduce the hatching rate of the larvae and suppress damage to the feed corn, allowing for the safe and successful growth of feed corn.

[0081] Furthermore, during the 2- to 8-leaf stage, when feeding damage by armyworm larvae is likely to lead to serious damage such as withering, the activity of armyworm is suppressed, the hatching rate of the larvae is reduced, and corn can be grown favorably without affecting its growth during the early 2- to 8-leaf stage.

[0082] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes modifications and additions that do not deviate from the gist of the present invention.

[0083] For example, in the above example, an embodiment in which night-time irradiation is performed on feed corn has been described, but the present invention is not limited to this, and the grasses to which the present invention is applicable may also be paddy rice, upland rice, edible corn, sorghum, sugarcane, oats, adlay, waxy millet, grasses, etc.

[0084] Furthermore, in the above examples, a mode of night-time irradiation was described for feed corn at the 2- to 8-leaf stage, but this is not limited thereto, and night-time irradiation may also be performed on plants at the 8-leaf stage or above, as long as it is possible to irradiate the grass plant with light from above.

[0085] Furthermore, in the above embodiment, the light is irradiated from above the grass family plant, but the present invention is not limited to this, and the light may be irradiated from the side or below the grass family plant.

Claims

1. A method for growing grass plants, comprising irradiating the grass plants with light having a central wavelength in the range of 380 nm to 550 nm at night to suppress the behavior of armyworm moth.

2. 2. The method for growing a grass plant according to claim 1, wherein the central wavelength of the light is in the range of 465 to 475 nm.

3. 2. The method for growing a grass plant according to claim 1, wherein the central wavelength of the light is in the range of 515 to 525 nm.

4. 2. The method for growing a grass plant according to claim 1, wherein the central wavelength of the light is in the range of 465 to 475 nm and in the range of 515 to 525 nm.

5. 2. The method for growing a grass plant according to claim 1, wherein the grass plant is maize.

6. 6. The method for growing a grass plant according to claim 5, wherein the corn is in the 2- to 8-leaf stage.

7. 4. The method for growing a grass plant according to claim 3, wherein the nighttime period is the period from sunset to late at night.

8. 8. The method for growing a grass family plant according to claim 1, wherein the light is irradiated from above the grass family plant.

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