Method and device for artificially lighting a plant in order to promote growth of the plant

Abstract

A method for artificially lighting a plant in order to promote growth of the plant (100), the method comprising a step of emitting radiation towards the plant (100) during a period referred to as the photoperiod, the emission step comprising at least the following two distinct phases: a) a red phase representing at least 10% of the photoperiod, during which only a primary type of radiation is emitted artificially, the primary radiation type being red; b) a multispectral phase, during which secondary types of radiation are emitted artificially, the secondary radiation types comprising at least two radiation types out of blue radiation, green radiation, red radiation and far-red radiation.

Description

[0001] DESCRIPTION

[0002] TITLE: Method and device for artificially illuminating a plant to promote plant development

[0003] FIELD OF INVENTION

[0004] The present invention relates to the field of artificial lighting of a plant, more specifically to a method and device for artificially lighting a plant in order to promote plant development.

[0005] STATE OF THE ART

[0006] Artificial lighting systems can be used to grow plants; these systems are called horticultural lighting. It is known that red light promotes the most photosynthesis. Red photons are indeed the most readily absorbed and assimilated by plants.

[0007] However, when plants are illuminated by monochromatic red light, one observes, among other things, plant weakening, a decrease in agronomic yield, and significant etiolation. This phenomenon is called "red syndrome".

[0008] Horticultural lighting systems are known to include LEDs (light-emitting diodes) designed to emit red light and one or more other colors of light, thus preventing "red syndrome." Specifically, to allow operators to see inside a growth chamber, these systems continuously emit white light in addition to the red. However, these systems consume a significant amount of energy.

[0009] Therefore, there is a need for an artificial lighting process for plants in order to promote plant development that allows for good agronomic yield while limiting energy consumption.

[0010] DESCRIPTION OF THE INVENTION

[0011] One aim of the invention is to provide a method and device for artificially lighting a plant in order to promote plant development which allows for good agronomic yield while limiting energy consumption.

[0012] According to a first aspect, a process of artificial lighting of a plant is proposed in order to promote plant development, the process comprising a step of emission of radiation towards the plant during a period called photoperiod, the emission step comprising at least the following two distinct phases: a) a red phase representing at least 10% of the photoperiod, during which only a primary radiation is artificially emitted, the primary radiation being red;

[0013] b) a multispectral phase, during which secondary radiations are artificially emitted, the secondary radiations comprising at least two radiations from among blue radiation, green radiation, red radiation and far-red radiation.

[0014] Depending on advantageous and non-limiting characteristics, taken alone or in any combination:

[0015] - the emission stage does not include a phase, called monospectral, in which only radiation of a specific color is artificially emitted, other than said red phase;

[0016] - the red phase represents less than 90% of the photoperiod;

[0017] - the red phase represents at least 40% of the photoperiod;

[0018] - secondary radiation includes a first radiation which is red radiation and at least a second radiation which is one of blue, green and far-red radiation, at least 5% of a total luminous intensity of secondary radiation corresponding to at least a second radiation; in other words, in the multispectral phase, less than 95% of a total luminous intensity of secondary radiation corresponds to red radiation;

[0019] - secondary radiation includes at least three types of radiation from among blue radiation, green radiation, red radiation and far-red radiation;

[0020] - secondary radiation includes blue radiation, green radiation, red radiation and far-red radiation;

[0021] - 5 to 30% of the total light intensity of secondary radiation corresponds to blue radiation, 5 to 30% of the total light intensity of secondary radiation corresponds to green radiation, 40 to 95% of the total light intensity of secondary radiation corresponds to red radiation and 1 to 20% of the total light intensity of secondary radiation corresponds to far-red radiation; - 15% of the total light intensity of secondary radiation corresponds to blue radiation, 15% of the total light intensity of secondary radiation corresponds to green radiation, 63% of the total light intensity of secondary radiation corresponds to red radiation and 7% of the total light intensity of secondary radiation corresponds to far-red radiation, the plant being preferably a young pepper plant, a young tomato plant or a tomato plant;- 18% of the total light intensity of secondary radiation corresponds to blue radiation, 18% of the total light intensity of secondary radiation corresponds to green radiation, 57% of the total light intensity of secondary radiation corresponds to red radiation and 7% of the total light intensity of secondary radiation corresponds to far-red radiation, the plant being preferably a young cucumber plant;

[0022] - 15% of the total light intensity of secondary radiation corresponds to blue radiation, 15% of the total light intensity of secondary radiation corresponds to green radiation, 60% of the total light intensity of secondary radiation corresponds to red radiation and 10% of the total light intensity of secondary radiation corresponds to far-red radiation, the plant being preferably a cucumber plant;

[0023] - red radiation is radiation with a wavelength between 600 and 700 nm;

[0024] - blue radiation is radiation with a wavelength between 400 and 500 nm, green radiation is radiation with a wavelength between 500 and 600 nm and far-red radiation is radiation with a wavelength between 700 and 800 nm;

[0025] - a luminous intensity of the primary radiation is greater than or equal to a total luminous intensity of all the secondary radiation(s);

[0026] - the luminous intensity of the primary radiation is at least 10% greater than the total luminous intensity of all the secondary radiation(s);

[0027] - the multi-spectrum phase is implemented after the red phase;

[0028] - the multi-spectrum phase is implemented before the red phase;

[0029] - the emission stage includes a first multispectral phase implemented before the red phase and a second multispectral phase implemented after the red phase; - a light intensity of the primary radiation and / or a light intensity of the secondary radiation and / or a duration of the photoperiod and / or a duration of one or each of the phases is modulated according to parameters relating to the development of the plant and / or parameters relating to the environment of the plant; - the first multispectral phase lasts 5 hours, the red phase lasts 7 hours and the second multispectral phase lasts 2 hours, the plant being preferably a young tomato plant or a young pepper plant;

[0030] - the first multispectral phase lasts 6 hours, the red phase lasts 8 hours and the second multispectral phase lasts 2 hours, the plant being preferably a young cucumber plant, a tomato plant or a cucumber plant.

[0031] According to a second aspect, an artificial lighting device for a plant is proposed in order to promote plant development comprising at least one primary lighting unit, at least two secondary lighting units and data processing means configured to control the lighting units to implement the process as previously presented.

[0032] Advantageously, the data processing means are configured to vary a light intensity of the primary radiation and / or a light intensity of the secondary radiation and / or a duration of the photoperiod and / or a duration of one or each of the phases according to parameters relating to the development of the plant and / or parameters relating to the environment of the plant.

[0033] DESCRIPTION OF THE FIGURES

[0034] Other features and advantages of the present invention will become apparent from the following description of a preferred embodiment. This description will be given with reference to the accompanying figures, including:

[0035] Figure 1 schematically represents an artificial lighting device;

[0036] Figure 2 represents the steps of an artificial lighting process;

[0037] Figures 3a, 3b, 3c, 3d, and 3e show results of the implementation of the process on cucumber plants;

[0038] Figures 4a, 4b, and 4c show results of implementing the process on tomato plants; Figures 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h, 5i, 5j, 5k, and 51 show results of implementing the process on young tomato plants;

[0039] Figures 6a, 6b, 6c, 6d, 6e, and 6f show results of implementing the process on young cucumber plants;

[0040] Figures 7a, 7b, 7c, 7d, 7e, and 7f show results of implementing the process on young pepper plants.

[0041] DETAILED DESCRIPTION OF THE INVENTION

[0042] The present invention, which belongs to the field of lighting and in particular to the field of agricultural and horticultural lighting, relates to a device and a method of artificial lighting intended to promote the development of a plant.

[0043] The term "plant" refers to any type of plant at any stage of its development. Specifically, a plant can be a seedling, a young plant, or a mature plant (a plant is at a more advanced stage of development than a seedling). A plant can be a seedling, a young plant, or a mature vegetable, fruit (for example, cucumber, pepper, tomato), flowering plant (for example, cannabis, chrysanthemum, or strawberry), etc. Therefore, a plant can be, for example, a young plant or a mature cucumber, pepper, tomato, or strawberry plant.

[0044] Indoor plants generally need supplemental light to compensate for a lack, or even a complete absence, of natural light. This is the case, for example, with plants in grow rooms that don't receive natural light. In these situations, it's necessary to artificially light the plant to allow it to develop, using appropriately positioned artificial light sources.

[0045] Natural lighting refers to the light produced by the sun, whether through direct sunlight and / or diffuse sunlight. Generally, natural lighting results from the combination of direct and diffuse sunlight.

[0046] Radiation is understood to mean a collection of photons propagating through space, advantageously towards a plant. In the following text, radiation of different colors, i.e., of different wavelengths, will be distinguished.

[0047] A plant grown in a greenhouse benefits from natural light that is more or less similar to what it would receive if grown outdoors. However, to optimize plant development, it is advisable to supplement this natural light, which depends in particular on the amount of sunlight, with appropriate artificial lighting.

[0048] Artificial lighting is defined as lighting produced or emitted by an artificial lighting device comprising at least one radiation source capable of producing radiation in at least one wavelength band.

[0049] In the case where the plant is in a place where there is no natural light, the plant can only be subjected to artificial lighting.

[0050] When a plant is in a location with natural light (for example, a greenhouse), it is exposed to overall lighting, which is a combination of natural and artificial light. To carry out photosynthesis, the plant therefore has access to radiant energy provided by this overall lighting.

[0051] A plant is illuminated, artificially and / or naturally, during a day for a period called its photoperiod. Outside of the photoperiod, the plant is not illuminated by either artificial or natural light. During the photoperiod, the plant can be illuminated artificially and / or naturally. Thus, if it is nighttime or the plant is in a room without natural light and is being artificially illuminated, it is in its photoperiod. The photoperiod is characterized by a duration, specifically a certain number of hours. In practice, the photoperiod is a single block, i.e., it is not segmented or interrupted by periods without light. In other words, during a day (24 hours), there are two periods: the photoperiod during which the plant is illuminated and the rest of the day, called the rest phase, during which the plant is not illuminated.It is generally not advisable to illuminate a plant 24 hours a day, as it is necessary to let it rest in darkness for at least a few hours each day. This resting period is necessary for the translocation of sugars accumulated during the daylight period. It should be noted, however, that the phrase "the photoperiod is not interrupted by periods without light" refers to periods without light of a significant duration, that is, greater than approximately 30 minutes. In other words, the photoperiod is considered continuous and uninterrupted if it includes, for example, one or more breaks of less than 30 minutes, such as a 10-minute break, during which there is no light.

[0052] In photosynthesis, not all radiation is created equal. The radiation useful for photosynthesis has wavelengths ranging from approximately 400 to 700 nanometers (nm). This is photosynthetically active radiation (PAR). The 400-700 nm range is also referred to as the photosynthetically active wavelength band. Radiation received by a plant in a wavelength range outside the 400-700 nm band, and particularly outside the 400-780 nm band, will be of very little use to it in terms of photosynthesis. This 400-780 nm wavelength band corresponds roughly to the visible spectrum; that is, the radiation emitted in this wavelength band corresponds to the light visible to the human eye.

[0053] We distinguish in particular between blue radiation, green radiation, red radiation and far-red radiation.

[0054] Advantageously, blue radiation is radiation with a wavelength between 400 and 500 nm.

[0055] Advantageously, green radiation is radiation with a wavelength between 500 and 600 nm

[0056] Advantageously, red radiation is radiation with a wavelength between 600 and 700 nm.

[0057] Advantageously, far-red radiation is radiation with a wavelength between 700 and 800 nm.

[0058] The level of photosynthesis achieved by a plant depends on the amount of light it receives. Indeed, the more intensely the plant is illuminated by a light source, the more carbon dioxide it will be able to assimilate.

[0059] The amount of light received by the plant corresponds advantageously to a photon flux density in the photosynthetically active band received by the plant. The received photon flux density is expressed in pmol / m³. 2 . s' 1 The photon flux density received is the number of photons, expressed here in pmol, received per unit area of ​​the plant, expressed in square meters (m²). 2 ), and per unit of time expressed in seconds.

[0060] The amount of light received by the plant depends on the photon flux of the radiation emitted in the photosynthetically active band towards the plant. By definition, a flux is the amount of light (for example, expressed in pmol) emitted by a light source in a given time (for example, expressed in seconds). The photon flux of the radiation is advantageously expressed in pmol. 1 .

[0061] In summary, the notion of quantity of light received by the plant quantifies the light received by the plant (from the plant's point of view) and the notion of photon flux quantifies the light emitted towards the plant (from the point of view of the artificial and / or natural light sources).

[0062] Generally speaking, the term "luminous intensity" of radiation or a set of radiations is used to encompass both the amount of light received by the plant and the photon flux. Thus, when we refer to luminous intensity, this can designate the amount of light received by the plant and / or the photon flux of radiation emitted towards the plant.

[0063] It is possible to characterize a set of emitted radiations by percentages associated with the distinct radiations composing the set. In other words, a set of radiations might, for example, include red radiation, blue radiation, and green radiation. To quantify the contribution of each radiation to the set, a percentage of photon flux can be used for each radiation. For example, the set of emitted radiations is considered to be characterized by a total photon flux. The set of radiations might include 80% red radiation, meaning that 80% of the total photon flux corresponds to red radiation; 5% blue radiation, meaning that 5% of the total photon flux corresponds to blue radiation; and 5% green radiation, meaning that 5% of the total photon flux corresponds to green radiation.This allows us to express a light intensity distribution of a set of radiations.

[0064] Other parameters influence the process of photosynthesis, such as ambient temperature, leaf temperature, ambient carbon dioxide levels, and ambient humidity. Generally, up to a certain limit corresponding to the plant's saturation point, the more light it receives, the faster it will grow due to photosynthesis.

[0065] The saturation point of a plant, or saturation threshold, is generally expressed in pmol.m' 2 .s' 1and designates a maximum of the photon flux density received by the plant in the photosynthetically active band. The saturation threshold corresponds to the amount of light energy received beyond which it will not assimilate any more carbon dioxide. Thus, at the saturation threshold, the amount of carbon dioxide assimilated by the plant reaches a ceiling that obviously depends not only on the type of plant concerned—that is, its species, variety, and stage of cultivation—but also on environmental conditions. Beyond the saturation threshold, the plant puts in place morphological mechanisms to protect itself and avoid light at the expense of its growth, and the rate of photosynthesis decreases. A critical threshold will cause the death of the plant.

[0066] To promote intensive cultivation, that is to say to obtain maximum production of the cultivated plant in a reduced time, artificial lighting makes it possible to optimize the growth of the plant.

[0067] In cases where plants do not receive natural light, artificial lighting allows for their development. Specifically, the artificial lighting method of the invention enables optimized plant growth. In cases where plants also receive natural light, advantageously, artificial lighting can be used to adequately supplement natural light at any time, so that the overall lighting, combining natural and artificial light, produces a photon flux density in the synthetically active photoband that is both maximum and strictly below the plant's saturation threshold. Artificial lighting is particularly useful for compensating for a lack of sunlight in winter or on particularly cloudy days.Artificial lighting can, for example, also be used to increase day length, that is, to provide light to cultivated plants before sunrise and / or after sunset. The artificial lighting method of the invention allows for optimized plant growth, even when the plant also benefits from natural light.

[0068] With reference to Figure 1, a device 1 for artificial lighting of a plant 100 is proposed in order to promote the development of the plant 100.

[0069] Device 1 comprises at least one primary lighting unit 10 and at least two secondary lighting units 20.

[0070] The primary lighting unit 10 is configured to emit primary radiation in a primary wavelength band.

[0071] The primary lighting unit 10 is configured to emit red radiation. Each secondary lighting unit 20 is configured to emit secondary radiation in a secondary wavelength band.

[0072] If the primary radiation is identical to a secondary radiation (i.e. they are of the same wavelength band), the primary lighting unit 10 can also be a secondary lighting unit 20 and vice versa.

[0073] The secondary lighting units 20 comprise at least one first secondary lighting unit 20a configured to emit first secondary radiation in a first secondary wavelength band and a second secondary lighting unit 20b configured to emit second secondary radiation in a second secondary wavelength band. The first secondary wavelength band is different from the second secondary wavelength band. More precisely, the first secondary wavelength band is different from the second secondary wavelength band such that the first secondary radiation is of a different color than the second secondary radiation.Advantageously, the first secondary radiation is one of red, blue, green, and far-red radiation, and the second secondary radiation is a different type from the first secondary radiation and is one of red, blue, green, and far-red radiation. Preferably, the first secondary lighting unit 20a is configured to emit a first red secondary radiation, and the second secondary lighting unit 20b is configured to emit a second blue secondary radiation.

[0074] Device 1 may include more than two secondary lighting units 20.

[0075] Device 1 may include three secondary lighting units 20. Preferably, the first secondary lighting unit 20a is configured to emit a first red secondary radiation, the second secondary lighting unit 20b is configured to emit a second blue secondary radiation, and a third secondary lighting unit 20c (not shown in the figures) is configured to emit a third far-red secondary radiation.

[0076] Device 1 may include four secondary lighting units 20. Preferably, the first secondary lighting unit 20a is configured to emit a first red secondary radiation, the second secondary lighting unit 20b is configured to emit a second blue secondary radiation, a third secondary lighting unit 20c (not shown in the figures) is configured to emit a third far-red secondary radiation and a fourth secondary lighting unit 20d (not shown in the figures) is configured to emit a fourth green secondary radiation.

[0077] Each lighting unit 10, 20 advantageously includes at least one light-emitting diode (LED). Some or all lighting units may include several LEDs. The use of LEDs is economically advantageous in terms of both electrical energy consumption and lifespan. Compared to other lighting solutions available on the market, LEDs offer particularly high energy efficiency.

[0078] According to one embodiment, the primary lighting unit 10 comprises at least one red monochromatic light-emitting diode (LED).

[0079] According to one embodiment, a secondary lighting unit 20 configured to emit red secondary radiation includes a red monochromatic LED.

[0080] According to one embodiment, a secondary lighting unit 20 configured to emit a secondary blue radiation includes a monochromatic blue LED.

[0081] In one embodiment, a secondary lighting unit 20 configured to emit far-red secondary radiation includes a far-red monochromatic LED. In another embodiment, a secondary lighting unit 20 configured to emit green secondary radiation includes a green monochromatic LED. Alternatively, and advantageously, a secondary lighting unit 20 configured to emit green secondary radiation includes a polychromatic LED producing white light and emitting between 25% and 80% of its radiation in the green range. Such an LED offers, in particular, a higher photon efficiency than a monochromatic LED producing green light.

[0082] Each lighting unit 10, 20 is designed to emit radiation towards at least one plant 100 within a specific wavelength band. Therefore, each lighting unit 10, 20 is designed to be positioned opposite at least one plant 100 so that the plant receives the radiation emitted by each unit when the unit is in operation.

[0083] Advantageously, the device 1 includes a power supply unit 13 capable of providing a rated electrical power Pn to the input of the device 1. The power supply unit 13 is preferably arranged to provide the primary lighting unit 10 with an electrical power P1, the first secondary lighting unit 20a with an electrical power P2a, and the second secondary lighting unit 20b with an electrical power P2b. Preferably, the power supply unit 30 is capable of providing different electrical powers to the lighting units 10 and 20.

[0084] Preferably, the device 1 also includes at least one detection unit 14 capable of collecting at least one signal representative of radiation produced by the device 1 and / or by natural lighting. Depending on one possibility, the detection unit 14 is a goniophotometer, a spectroradiometer, and / or a PAR meter.

[0085] Device 1 includes data processing means 15 configured to control the lighting units 10, 20 so as to implement an artificial lighting process as will be described later.

[0086] The data processing means 15 are advantageously configured to enable the activation and deactivation of the lighting units 10, 20. In particular, the data processing means 15 are advantageously configured to activate the lighting units 10, 20 for a certain duration and deactivate them for a certain duration. In an embodiment where one or more of the processing units 10, 20 comprise polychromatic LEDs, the data processing means 15 are configured to activate these lighting units 10, 20 so that they emit radiation of a predetermined wavelength.

[0087] Advantageously, the data processing means 15 are configured to control the power supply unit 13 so that said power supply unit 13 supplies energy respectively to the lighting units 10, 20 according to respective electrical powers and at given times.

[0088] Advantageously, the data processing means 15 are configured to control the power supply unit 13 and / or the lighting units 10, 20 in such a way as to vary the light intensity of the radiation, the duration of the photoperiod and / or the duration of one or each of the phases of the photoperiod (red phase and / or multispectral phase which will be presented later) according to parameters relating to the development of the plant and / or parameters relating to the environment of the plant.

[0089] Preferably, the data processing means 15 are configured to control the power supply unit 13 and / or the lighting units 10, 20 in such a way as to vary the amount of energy received by the plant, i.e., the received photon flux density, according to the parameters. To this end, the data processing means 15 can be configured to receive, from the detection unit 14, a measurement of the amount of light received by the plant, and, based on this measurement and a target amount of light, determine whether to increase or decrease the amount of light received by the plant. Advantageously, the data processing means 15 are configured to control the power supply unit 13 so that it provides greater or lesser electrical power to the lighting units 10, 20. By varying this electrical power, the luminous intensity of the radiation emitted by the lighting units varies.

[0090] For example, parameters relating to plant development may include the price of electricity and / or an estimated selling price of an agricultural product derived from plant 100. In such a way, the data processing means 15 can be configured to adapt the electrical consumption of device 1 in order to guarantee economic benefits of a certain value.

[0091] Parameters relating to the plant's environment may, for example, include humidity levels, light intensity from natural (i.e. solar) radiation, temperature, etc.

[0092] Preferably, the parameters relating to plant development and / or the plant environment include one or more parameters determined from the signal collected by the detection unit 14, representative of radiation produced by the device 1 and / or by natural lighting. More specifically, the data processing means 15 are configured to control the power supply unit 13 and the lighting units 10, 20 so that the amount of energy from one or more radiations received by the plant 100 reaches a certain value, possibly without exceeding another value corresponding to the saturation threshold.

[0093] With reference to Figure 2, a method of artificial lighting of a plant is proposed in order to promote the development of the plant 100.

[0094] Artificial lighting is defined as lighting that exclusively involves the emission of artificial radiation. However, plants may be located in areas where natural light penetrates. Therefore, artificial lighting can be combined with natural light. It can also be used in areas where plants do not receive natural light. This method increases agricultural yields while minimizing electricity consumption in both cases (whether or not natural light is used).

[0095] The process includes a step of emitting radiation towards the plant for 100 days during one photoperiod. "Towards the plant" means that the radiation is emitted in such a way that the plant receives it. In other words, the lighting units are positioned facing the plant so that it benefits from the radiation when the unit(s) emit it.

[0096] The emission stage comprises at least two distinct phases. By distinct, it is understood that the two phases do not overlap temporally.

[0097] Furthermore, the phases of the emission stage are consecutive and are not separated by a period without artificial lighting. By period without artificial lighting, we mean a period of significant duration, that is, lasting more than approximately 30 minutes. Consequently, the phases of the emission stage are considered consecutive even if they are separated by a short period without artificial lighting, i.e., a period of less than 30 minutes without artificial lighting.

[0098] Furthermore, advantageously, there is only one emission phase in a day (i.e., 24 hours) during which the plant receives artificial light. During the rest of the day, which does not correspond to the emission phase, the plant is not subjected to artificial light. In other words, the emission phase represents 100% of the photoperiod. Consequently, the sum of the proportions of the phases included in the emission phase equals 100% of the photoperiod.

[0099] The emission stage includes a red phase (a) representing at least 10% of the photoperiod, during which only primary radiation is artificially emitted, the primary radiation being red radiation. The primary radiation is artificially emitted, that is, by one or more primary lighting units 10. By "only," it is understood that, during the red phase, the only artificial radiation emitted, i.e., the only artificial radiation benefiting the plant, is red. The red phase corresponds to a phase during which the plant 100 receives artificial red radiation. In other words, the red phase corresponds to a phase during which at least one primary lighting unit 10 emits artificial red radiation towards the plant 100. By red, it is preferably understood to mean radiation with a wavelength between 600 and 700 nm.

[0100] Red light is the type of radiation that promotes the most photosynthesis. Red photons are indeed the most readily absorbed and assimilated by plants.

[0101] The red phase lasts at least 10% of the photoperiod. For example, if the photoperiod lasts 10 hours, then the red phase lasts at least 1 hour.

[0102] Advantageously, the red phase lasts at least 30% of the photoperiod, preferably at least 40%, 50%, 60%, or 70%. The red phase can last at least 80% or even 90% of the photoperiod. The longer the red phase, the more photosynthesis occurs. However, the red phase should not last 100% of the photoperiod, as this can lead to "red syndrome." Therefore, it is preferable that the red phase lasts less than 90% of the photoperiod.

[0103] Advantageously, the statement "only primary radiation is artificially emitted, the primary radiation being red radiation" means that 100% of the artificial light intensity during the red phase corresponds to red radiation. In other words, advantageously, no radiation of any color other than red is artificially emitted during the red phase.

[0104] Advantageously, 100% of the luminous intensity of the primary radiation emitted during the red phase corresponds to red radiation. In practice, 100% is understood to mean "approximately 100%." ​​Indeed, in general, for example when using a monochromatic red LED, in addition to the emitted red radiation, a residual far-red radiation is emitted. Thus, when it is stated that 100% of the luminous intensity of the primary radiation emitted during the red phase corresponds to red radiation, this can mean in practice that a very small percentage corresponds to a non-red residual radiation (i.e., this residual radiation is generally far-red). The residual radiation corresponds at most to 3%, or even at most to 1%, of the luminous intensity of the primary radiation.

[0105] Light intensity can be defined as the amount of light received by the plant corresponding to primary radiation or as the photon flux of primary radiation. Indeed, whether one measures the amount of light received by the plant corresponding to primary radiation (preferably in pmol / m²) is sufficient. 2 .s' 1 ) or the photon flux of the primary radiation (preferably in pmol.s' 1In any case, it will be advantageous to have at least 100% of each of these quantities corresponding to red radiation. By the quantity of light received by the plant corresponding to primary radiation, we mean that we are not considering the quantity of light received by the plant corresponding to other radiations such as natural radiation. If 100% of the quantity of light received by the plant corresponding to primary radiation corresponds to red radiation, then 100% of the photon flux of primary radiation corresponds to red radiation, and vice versa.

[0106] The red phase aims to optimize the phenomenon of photosynthesis and promotes plant growth.

[0107] Advantageously, the emission stage does not include any monospectral (or monochromatic, or single-color) phase other than the red phase. Monospectral is defined as a phase during which only radiation of a specific color is artificially emitted. In other words, it is a phase where only one color is emitted. As such, the red phase is a monospectral phase, which is red. Thus, the process advantageously does not include any phase in which only one color is emitted, except for the red phase(s). In other words, the process, more precisely the emission phase, advantageously does not include any phase in which only one color other than red is emitted. In other words, the only monospectral phase(s) of the process are red. Consequently, the plant is never subjected solely to blue, green, or far-red radiation.Thus, the process does not include a blue, green, or far-red phase—that is, a phase in which only blue, green, or far-red radiation, respectively, is emitted. Indeed, as will be explained, it is the inclusion of a red phase and one or more multispectral phases in the process that allows for improved agronomic yields while limiting energy consumption.

[0108] The emission step of the process further includes a multispectral phase (b) during which secondary radiation is emitted. This secondary radiation comprises at least two of the following: blue, green, red, and far-red. The multispectral phase is a multicolored phase during which radiation of several colors is emitted towards the plant. This helps to prevent the occurrence of the "red syndrome" phenomenon.

[0109] Secondary radiation is purely artificial.

[0110] The existence of the multispectral phase indicates that the red phase does not last 100% of the photoperiod. Preferably, the multispectral phase represents at least 10% of the photoperiod. Advantageously, the multispectral phase represents less than 90% of the photoperiod.

[0111] Advantageously, the radiation artificially emitted during the emission stage, i.e., in the red and multispectral phases, is all emitted by one or more light-emitting diodes (LEDs). This notably allows for limiting energy consumption and precisely controlling the emitted wavelengths / colors.

[0112] Advantageously, the radiation in the multispectral phase is emitted by separate light-emitting diodes. In this way, the radiation, and in particular the intensities and wavelengths of each radiation, are precisely controlled.

[0113] Advantageously, during the multispectral phase, secondary radiation includes a first radiation that is red radiation and at least a second radiation that is one of blue, green, and far-red radiation. This helps to avoid the "red syndrome" while promoting photosynthesis.

[0114] Advantageously, at least 5% of the total luminous intensity of secondary radiation corresponds to at least one second radiation. In other words, less than 95% of the total luminous intensity of secondary radiation corresponds to the first radiation, which is red. By "less than 95%", it is understood that 95% can be included in this formulation, particularly in the case where 5% of the total luminous intensity of secondary radiation corresponds to at least one second radiation, and therefore 95% of the total luminous intensity of secondary radiation corresponds to the first radiation, which is red.

[0115] The total light intensity of the secondary radiation(s) corresponds to the light intensity of all the secondary radiation. Light intensity can be defined as the amount of light received by the plant from the secondary radiation or as the photon flux from all the secondary radiation. Indeed, whether one measures the amount of light received by the plant from the secondary radiation (preferably in pmol / m²) is sufficient, the total light intensity can be defined as the amount of light received by the plant from the secondary radiation (preferably in pmol / m²). 2 .s' 1 ) or the photon flux of all secondary radiation (preferably in pmol.s' 1In any case, at least 5% of each of these quantities will correspond to non-red radiation. By the quantity of light received by the plant corresponding to secondary radiation, we mean that we are not considering the quantity of light received by the plant corresponding to other radiations such as natural radiation. If 5% of the quantity of light received by the plant corresponding to secondary radiation corresponds to blue radiation, then 5% of the photon flux of secondary radiation corresponds to blue radiation, and vice versa. Advantageously, at least 10%, or even at least 15%, or even at least 20%, of the total luminous intensity of secondary radiation corresponds to at least one other type of radiation.

[0116] In a preferred embodiment, the secondary radiation comprises a first red radiation and a second blue radiation. This allows for improved agricultural yields while limiting the energy consumption of device 1.

[0117] Advantageously, the secondary radiation comprises at least (or only) three radiations from among blue, green, red, and far-red radiation. In other words, at least three radiations are artificially emitted during the multispectral phase. Advantageously, the secondary radiation comprises red radiation and at least (or only) two other radiations from among blue, green, and far-red radiation. For example, the secondary radiation comprises a first radiation that is red radiation and at least (or only) two second radiations, one of which is blue and one of which is far-red radiation. Alternatively, the secondary radiation comprises a first radiation that is red radiation and at least (or only) two second radiations, one of which is far-red and one of which is green radiation.Alternatively, the secondary radiation comprises a primary red radiation and at least (or only) two secondary radiations, one blue and one green. These embodiments allow for improved agricultural yields while limiting the energy consumption of device 1.

[0118] In a preferred embodiment, the secondary radiation comprises a first radiation, which is red radiation, and two second radiations, one blue and one far-red. This further improves agricultural yields while limiting the energy consumption of device 1.

[0119] In a preferred embodiment, the secondary radiation comprises a first radiation, which is red radiation, and three second radiations: blue radiation, far-red radiation, and green radiation. This further improves agricultural yields while limiting the energy consumption of device 1. This is demonstrated in the examples presented later.

[0120] Advantageously, 5 to 30% of the total light intensity of secondary radiation corresponds to blue radiation, 5 to 30% of the total light intensity of secondary radiation corresponds to green radiation, 40 to 95% of the total light intensity of secondary radiation corresponds to red radiation and 1 to 20% of the total light intensity of secondary radiation corresponds to far-red radiation.

[0121] In one embodiment, the plant is a young pepper plant, a young tomato plant, or a tomato plant. Advantageously, 15% of the total secondary radiation intensity corresponds to blue radiation, 15% to green radiation, 63% to red radiation, and 7% to far-red radiation. This allows for improved agronomic yield from a young pepper plant, a young tomato plant, or a tomato plant while limiting electricity consumption.

[0122] In one embodiment, the plant is a young cucumber plant. Advantageously, 18% of the total secondary radiation intensity corresponds to blue radiation, 18% to green radiation, 57% to red radiation, and 7% to far-red radiation. This allows for a better agronomic yield for a young cucumber plant while limiting electricity consumption.

[0123] In one embodiment, the plant is a cucumber plant. Advantageously, 15% of the total secondary radiation intensity corresponds to blue radiation, 15% to green radiation, 60% to red radiation, and 10% to far-red radiation. This allows for a better agronomic yield for a cucumber plant while limiting electricity consumption.

[0124] In one embodiment, the luminous intensity of the primary radiation is equal to the luminous intensity of all secondary radiation. In other words, the luminous intensity of the radiation during the red phase is equal to the luminous intensity of the radiation during the multispectral phase. In this case, the same agricultural yield is maintained while reducing electricity consumption compared to the prior art. In another embodiment, the luminous intensity of the primary radiation is greater than the luminous intensity of all secondary radiation. In other words, the luminous intensity of the radiation during the red phase is greater than the luminous intensity of the radiation during the multispectral phase. In this case, a better agricultural yield is obtained with little or no increase in electricity consumption compared to the prior art.

[0125] Advantageously, the total luminous intensity of the primary radiation is at least 10% greater, preferably at least 15% greater, and even more preferably at least 20% greater, than the luminous intensity of all the secondary radiation(s). This makes it possible to obtain a very good agricultural yield with little or no increase in electricity consumption compared to the prior art.

[0126] Advantageously, the light intensity of the primary radiation and / or the light intensity of the secondary radiation and / or the duration of the photoperiod and / or the duration of one or each of the phases is modulated according to parameters relating to the development of the plant and / or parameters relating to the environment of the plant.

[0127] For example, the light intensity of the primary radiation and / or the light intensity of the secondary radiation can be modulated according to the light intensity of natural radiation (which is a parameter related to the plant's environment). In other words, the emission stage of the process includes the detection of natural radiation, i.e., solar radiation, and the light intensity of the artificial radiation is adjusted accordingly. For example, during the red phase, the light intensity of the radiation can be increased or decreased depending on the amount of natural red radiation. Alternatively, the duration of the red phase and / or the multispectral phase can be increased or decreased depending on the duration of natural light (i.e., the length of the day).

[0128] The emission stage of the process may comprise only two phases: a single red phase and a single multispectral phase. In one embodiment, the red phase is implemented before the multispectral phase (from the perspective of a 24-hour day beginning at midnight and ending at 11:59 PM). In another embodiment, the red phase is implemented after the multispectral phase. This can, under certain circumstances, allow for better yield while limiting energy consumption. The choice of scheduling the red phase before or after the multispectral phase depends on various circumstances (i.e., parameters), such as the type of plant and / or the characteristics of natural lighting during the day. The emission stage of the process may comprise three phases: a single red phase and two multispectral phases.In this case, the emission stage of the process includes a multispectral phase implemented before the red phase and a multispectral phase implemented after the red phase. This can, under certain circumstances, allow for better efficiency while limiting energy consumption.

[0129] The emission stage, and therefore the photoperiod, may consist of a single red phase. Alternatively, the emission stage, and therefore the photoperiod, may consist of several red phases, with two red phases interspersed with a multispectral phase.

[0130] As explained previously, the photoperiod is a single block and is not considered interrupted if it includes, for example, one or more pauses of less than 30 minutes, such as a 10-minute pause, during which there is no illumination. Similarly, a red phase is considered a single red phase even if it includes one or more pauses of less than 30 minutes, such as a 10-minute pause, during which there is no illumination. In other words, in this case, it is not considered that there are multiple red phases. Likewise, a multispectral phase is considered a single multispectral phase even if it includes one or more pauses of less than 30 minutes, such as a 10-minute pause, during which there is no illumination.

[0131] According to one embodiment, the plant is a young tomato plant or a young pepper plant and the emission stage includes a first multispectral phase lasting 5 hours, a red phase lasting 7 hours and a second multispectral phase lasting 2 hours.

[0132] According to one embodiment, the plant is a young cucumber plant, a tomato plant or a cucumber plant and the emission step includes a first multispectral phase lasting 6 hours, a red phase lasting 8 hours and a second multispectral phase lasting 2 hours.

[0133] In one embodiment, the plant is a young plant or a strawberry plant. EXAMPLES

[0134]

[0135] cucumber

[0136] Materials and methods

[0137] These two experiments were conducted with cucumber plants in two indoor growing rooms at PARC (Photobiologic and Agronomy Research Center). The experiment began on December 1, 2023, and ended on April 18, 2024. Four light treatments were compared. Plant material and growing conditions

[0138] Cucumber seeds of two varieties, Roadie (Ri jk Zwaan) and Dee Votion (Enza Zaden), were sown in Grodan rockwool plugs and then covered with perlite. From the seedling stage until the 5-6 leaf stage, all seedlings received the same light treatment. The seedlings were transplanted onto double gutters on Grodan rockwool slabs, in a high-wire culture, on January 3, 2024. The planting density was 2.8 plants / m². Light treatments were applied the following day.

[0139] Each light treatment was repeated twice in the space. Each grow room had 5 rows of gutters. The compartment was divided into blocks of 20m² each. Each block corresponded to one light treatment. Only the plants in the middle row were used for analysis.

[0140] The climate in the growing rooms was managed by a Hoogendoorn horticultural climate computer. The conditions were as follows:

[0141] - Day / Night Temperature: 24 / 19 °C

[0142] - Relative humidity: 70-85%

[0143] - CO2: 750 ppm

[0144] The air temperature was recorded in each compartment and showed no significant difference.

[0145] Light treatment

[0146] The lighting used is the REDT 680 developed by RED Horticulture. This lighting allows for the control of 4 colors.

[0147] Before the lighting treatments were implemented, the light intensity was measured and adjusted at the plant's top. An Apogee MQ-500 spectroradiometer was used to verify the light intensities.

[0148] The definition of the wavelengths of the colors blue, green, red and far-red is as follows:

[0149] - Blue: 400-500 nm

[0150] - Green: 500-600 nm

[0151] - Red: 600-700 nm

[0152] - Far red: 700-800 nm

[0153] To control the spectral qualities, a PG200N spectroradiometer from the brand UPRteka was used.

[0154] Characteristics of light treatments

[0155] - Photoperiod: 16h - Luminous intensity: 315 pmol.m' 2 .s' 1 ± 25 pmol.m' 2 .s' 1

[0156] - DLI (Daily light integral): 18 mol.m' 2 .s' 1

[0157] - Spectral quality (B means blue, G means green, R means red and FR means far-red; different phases are separated by the sign "-"; the numbers indicate a light intensity distribution):

[0158] Treatment 1: 15B / 15G / 60R / 10FR 16h

[0159] . Treatment

[0160]

[0161] Treatment 3: 15B / 15G / 60R / 10FR 6h

[0162]

[0163] 15B / 15G / 60R / 10FR 2h (20% increase in luminous intensity for the 100R phase so that the luminous intensity is 378 pmol.m' 2 .s' 1 )

[0164] • Treatment 4: 5B / 5G / 90R 16h

[0165] For example, "15B / 15G / 60R / 10FR 16h" denotes a 16-hour multispectral phase during which 15% of the light intensity is blue, 15% of the light intensity is green, 60% of the light intensity is red, and 10% of the light intensity is far-red.

[0166] Plant analysis

[0167] Morphological measurements

[0168] - Sample: 6 plants of the Roadie variety / 6 plants of the Dee Votion variety / 6 plants of the Roadie variety: 18 plants per treatment

[0169] - Duration: 13 weeks of measurements

[0170] Plant monitoring

[0171] Frequency: once a week.

[0172] Growth, Height (cm)

[0173] Measure using a meter stick from the base of the plant to the top of the plant (first measurement). Then, for the following weeks, measure the difference in height between the mark made on the growing wire the previous week and the current week (new top height).

[0174] Number of sheets

[0175] Counting the number of fully unfurled leaves after the cotyledons. From one week to the next, only the leaves located above the mark placed on the last leaf of the previous week are counted.

[0176] Number of cucumbers

[0177] Number of cucumbers below the last open flower. Cucumbers with the last open flower are also counted. Fruit tracking

[0178] Frequency: once a week

[0179] Weight ( )

[0180] The weight of the harvested cucumber(s) is measured on a precision scale for each plant checked.

[0181] Number of fruits harvested

[0182] Counting the number of fruits harvested across the entire plot (even outside of monitored plants).

[0183]

[0184] Statistical analyses were performed on the data obtained for all plants in each replicate and for each of the measured criteria. These analyses were processed using the R software. The data were analyzed with a one-way analysis of variance (ANOVA, p < 0.05) (light treatment). If significant differences were found among the variances studied, the means were then compared pairwise using Tukey's test (Honest Significant Difference, HSD, p < 0.05). When the residuals did not meet the conditions of normality and homoscedasticity, the Kruskal-Wallis test was performed, followed by a Wilcoxon-Mann-Whitney test (p < 0.05).

[0185] Results

[0186] Effects of different light treatments on cucumber production

[0187] Figure 3a illustrates the impact of the light spectrum emitted by LED lighting on the cumulative number of fruits per m 2 Figures 3a and 3b illustrate the impact of the light spectrum emitted by LED lighting on the cumulative number of fruits per m² over 13 weeks of harvest for the Dee Votion variety, and Figure 3b illustrates the impact of the light spectrum emitted by LED lighting on the cumulative number of fruits per m² over 13 weeks of harvest for the Roadie variety. Figures 3a and 3b illustrate, for each treatment, the evolution of the number of fruits per m². 2 depending on the number of weeks.

[0188] For both varieties, the same trends are observed. Treatment 4 results in the lowest number of fruits. Treatments 1 and 2 show similar fruit production. Treatment 3 increases the number of fruits by 8.8% compared to treatments 1 and 2 for Dee Votion, and by 6.2% and 5.7% compared to treatments 1 and 2, respectively, for Roadie.

[0189] Figure 3c illustrates the impact of the light spectrum emitted by LED lighting on the cumulative yield in kg / m² 2 over 13 weeks of harvest for the Dee Votion variety and figure 3d illustrates the impact of the light spectrum emitted by LED lighting on the cumulative yield in kg / m² 2 over 13 weeks of harvest for the Roadie variety. Figures 3c and 3d illustrate, for each treatment, the evolution of fruit yield in kilograms per m² 2 depending on the number of weeks.

[0190] As with the number of fruits, treatment 4 resulted in the lowest yield for both varieties. Treatments 1 and 2 were similar in terms of yield. Treatment 3 increased the yield. For Dee Votion, treatment 3 resulted in yield increases of 15.8%, 6.9%, and 8.2% compared to treatments 4, 1, and 2, respectively. The same trend was observed for Roadie, where treatment 3 resulted in yield increases of 8.6%, 4.9%, and 6% compared to treatments 4, 1, and 2, respectively.

[0191] Figure 3e is a table illustrating the impact of the light spectrum emitted by LED lighting on the number of fruits harvested and the cumulative yield in kg / m² 2 over 13 weeks of harvest (Dee Votion and Roadie varieties). For each Trt treatment, the cumulative number of fruits harvested per m 2 is indicated in the first column and the average cumulative weight of the harvested fruit in kilograms per m 2is indicated in the second column.

[0192] Discussion

[0193] Cucumbers are sold individually and must meet certain size requirements for the target market. Therefore, our discussion will focus primarily on the number of fruits produced. Specifically, the number of fruits considered when calculating the cumulative fruit per square meter 2 These are fruits that meet a certain size standard.

[0194] Reduced electricity consumption without compromising agronomic performance thanks to the red alternative spectrum

[0195] Treatment 1 is the reference treatment for agronomic performance. Indeed, compared to treatment 4, which is the market standard, treatment 1 increases the number of cucumbers produced by 4.7% and 4.4% for Dee Votion and Roadie respectively.

[0196] However, treatment 1 is energy-intensive. Therefore, treatment 2 was developed and, thanks to the use of the red dynamic spectrum, treatment 2 reduces consumption by 6% while maintaining the same agronomic performance.

[0197] An increase in agronomic performance with increased light intensity of red monochromatic light

[0198] Treatment 3 (which corresponds to treatment 2 with a 20% increase in light intensity during the 8 hours of 100% red light) provides an additional 10% artificial light input over the total photoperiod, in terms of light intensity (specifically in terms of PPFD, i.e., photon flux density in the photosynthetically active band received by the plant), compared to the other light treatments. This leads to improved agronomic performance with an increased number of fruits and yield per square meter.2 .

[0199] Conclusion

[0200] It has been demonstrated here that, even in the absence of any natural light, on the production of high wire cucumbers, it is possible to use artificial lighting with a monochromatic red spectrum of 660nm at 50% of the total photoperiod duration, completely avoiding the "red syndrome" phenomenon, provided that it is combined by at least one complementary period (before and / or after) with another polychromatic light comprising at least one other wavelength in a proportion between 10 and 100%.

[0201] Using a 100% red spectrum over part of the photoperiod:

[0202] - It was observed that agronomic efficiency, and therefore yield, was maintained while reducing electricity consumption if the amount of PAR supplied during the phases was equivalent to the control (i.e., during treatment 1).

[0203] - An increase in plant yield has been observed, resulting in better biomass production and an advanced stage of development, if the amount of PAR supplied is increased.

[0204] PAR is photosynthetic active radiation. The wavelengths that make up PAR are between 400 and 700 nm and are used for photosynthesis. Since PAR is not a metric but an absorption model, several units are used to characterize light for plant production. Similar to lumens and lux, the greenhouse industry uses a set of units to best define lighting within its environment.

[0205]

[0206] tomato

[0207] Materials and methods

[0208] This experiment was conducted with tomato plants in two indoor growing rooms at PARC (Photobiologic and Agronomy Research Center). The experiment began on June 19, 2023, and ended in November 2024. Four light treatments were compared.

[0209] Plant material and growing conditions: Tomato seedlings, Tastyno variety (Gauthier Semence), were received on June 19, 2024, with two main heads. The seedlings were transplanted into a double gutter system on a Grodan rockwool slab in a raised bed on June 19, 2024. The plant density was 2.8 plants / m². 2 The lighting treatments were applied on June 19, 2024.

[0210] For both trials, each light treatment was repeated twice in the space. Each growth chamber had 5 rows of gutters. The compartment was divided into blocks of 20 m² each. Each block corresponded to one light treatment. Only the plants in the middle row were used for analysis.

[0211] The climate in the growth chambers was controlled by a Hoogendoorn horticultural climate computer. The conditions were as follows:

[0212] - Day / Night Temperature: 24 / 19 °C

[0213] - Relative humidity: 70-85%

[0214] - CO2: 750 ppm

[0215] The air temperature was recorded in each compartment and showed no significant difference.

[0216] Light treatments

[0217] The lighting used is the REDT 680 developed by RED Horticulture. This lighting allows control of 4 colors.

[0218] Before installing the light treatments, the light intensity was measured and adjusted at the plant's crown. An Apogee MQ-500 spectroradiometer was used to verify the light intensities.

[0219] The wavelengths of the colors blue, green, red, and far-red have been defined as follows:

[0220] - Blue: 400-500 nm

[0221] - Green: 500-600 nm

[0222] - Red: 600-700 nm

[0223] - Far red: 700-800 nm

[0224] To verify the spectral qualities, a PG200N spectroradiometer from the company UPRtek was used.

[0225] Characteristics of light treatments

[0226] - Photoperiod: 16 hours

[0227] - Luminous intensity: 315 pmol.m' 2 .s' 1 ± 25 pmol.m' 2 .s' 1

[0228] - DLI (Daily light integral): 18 mol.m' 2 .s' 1 TJ

[0229] - Spectral quality (B means blue, G means green, R means red and FR means far-red; different phases are separated by the sign "-"; the numbers indicate a light intensity distribution):

[0230] Treatment 1: 15B / 15G / 63R / 7FR 16h

[0231] . Treatment

[0232]

[0233] Treatment 3: 15B / 15G / 63R / 7FR 6h

[0234]

[0235] 15B / 15G / 63R / 7FR 2h (20% increase in luminous intensity for the 100R phase so that the luminous intensity is 378 pmol.m' 2 .s' 1 )

[0236] • Treatment 4: 5B / 5G / 90R 16h

[0237] For example, "15B / 15G / 63R / 7FR 16h" designates a 16-hour multispectral phase during which 15% of the light intensity is blue, 15% of the light intensity is green, 63% of the light intensity is red, and 7% of the light intensity is far-red.

[0238]

[0239] Morphological measurements

[0240] - Sample: 18 plants per treatment

[0241] - Duration: 13 weeks of measurements

[0242] Fruit tracking

[0243] Frequency: once a week

[0244] Weight ( )

[0245] The weight of the harvested tomato(es) is measured on a precision scale for each plant checked.

[0246] Number of fruits harvested

[0247] Counting the number of fruits harvested across the entire plot (even outside of monitored plants).

[0248]

[0249] Statistical analyses were performed on the data obtained for all plants in each replicate and for each of the measured criteria. These analyses were processed using the R software. The data were analyzed with a one-way analysis of variance (ANOVA, p < 0.05) (light treatment). If significant differences were found among the variances studied, the means were then compared pairwise using Tukey's test (Honest Significant Difference, HSD, p < 0.05). When the residuals did not meet the conditions of normality and homoscedasticity, the Kruskal-Wallis test was performed, followed by a Wilcoxon-Mann-Whitney test (p < 0.05).

[0250] Results

[0251] Effects of different light treatments on tomato production

[0252] Figure 4a illustrates the impact of the light spectrum emitted by LED lighting on the cumulative number of fruits harvested per m 2over 13 weeks of harvest. Figure 4a shows, for each treatment, the evolution of the number of fruits per m 2 depending on the number of weeks.

[0253] Treatment 4 resulted in the lowest number of fruits. Treatments 1 and 2 showed similar fruit production, although treatment 2 resulted in a slight increase in the number of fruits. Treatment 3 resulted in an increase in the number of fruits of 10% and 8.2% compared to treatments 1 and 2, respectively.

[0254] Figure 4b illustrates the impact of the light spectrum emitted by LED lighting on the cumulative yield in kg / m² over 13 weeks of harvest. Figure 4b shows, for each treatment, the evolution of fruit yield in kilograms per m² 2 depending on the number of weeks.

[0255] As with the number of fruits, treatment 4 results in the lowest yield. Treatment 2 allows for a slight increase in yield compared to treatment 1. Treatment 3 allows for a yield increase of 12.9% and 9.7% compared to treatments 1 and 2, respectively.

[0256] Figure 4c is a table showing the impact of the light spectrum emitted by LED lighting on the number of fruits harvested and the cumulative yield (kg / m²). 2 ) over 13 weeks of harvest. For each treatment Trt, the cumulative number of fruits harvested per m 2 is indicated in the first column and the average cumulative weight of the harvested fruit in kilograms per m 2 is indicated in the second column.

[0257] Discussion

[0258] Reduced electricity consumption without compromising agronomic performance thanks to the red alternative spectrum

[0259] Treatment 1 is the reference treatment for agronomic performance. Indeed, compared to Treatment 4, which is the market standard, it increases yield by 5.5%. However, Treatment 1 is energy-intensive. Therefore, Treatment 2 was developed, and thanks to the use of the dynamic red spectrum, Treatment 2 reduces consumption by 5% while maintaining the same agronomic performance. An increase in agronomic performance is achieved by increasing the light intensity of the red monochromatic spectrum.

[0260] Treatment 3 (which corresponds to treatment 2 with a 20% increase in light intensity during the 8 hours of 100% red light) provides an additional 10% artificial light input over the total photoperiod, in terms of light intensity (specifically in terms of PPFD, i.e., photon flux density in the photosynthetically active band received by the plant), compared to the other light treatments. This leads to improved agronomic performance with an increased number of fruits and yield per square meter. 2 .

[0261] Conclusion

[0262] It has been demonstrated here that, even in the absence of any natural light, on the production of high wire tomatoes, it is possible to use artificial lighting whose spectrum is monochromatic red 660nm at 50% of the total photoperiod duration, completely avoiding the "red syndrome" phenomenon, provided that it is combined by at least one complementary period (before and / or after) with another polychromatic light comprising at least one other wavelength in a proportion between 10 and 100%.

[0263] Using a 100% red spectrum over part of the photoperiod:

[0264] - It was observed that agronomic efficiency, and therefore yield, was maintained while reducing electricity consumption if the amount of PAR supplied during the phases was equivalent to the control (i.e., during treatment 1).

[0265] - An increase in plant yield has been observed, resulting in better biomass production and an advanced stage of development, if the amount of PAR supplied is increased.

[0266]

[0267] tomato

[0268] Materials and methods

[0269] This experiment was conducted with young tomato plants in an indoor growing room at PARC (Photobiologic and Agronomy Research Center). The experiment began on May 28, 2024, and ended on July 22, 2024. Three light treatments were compared.

[0270] Plant material and growing conditions: Tomato seeds of two varieties, Brioso (Rijk Zwaan) and Xaverius (Axia), were sown in Grodan rockwool plugs and then covered with perlite. After two weeks, they were grafted onto DRO141 rootstock.

[0271] The plants were transplanted into Grodan rockwool cubes on June 24, 2024. There was one plant per cube with two heads. The topping was done on June 24, 2024. The density was reduced from 50 heads per cube. 2 with 18 heads. m' 2 after spacing. The light treatments were applied on June 22, 2024.

[0272] For this experiment, each light treatment was repeated twice in the space. The growth chamber was divided into 6 blocks. Each block corresponded to one light treatment. Only plants considered non-boundary were measured.

[0273] The climate in the growth chambers was controlled by a Hoogendoorn horticultural climate computer. The conditions were as follows:

[0274] - Day / night temperature: 23 / 21°C for the first 3 weeks, then 21.5 / 19.5°C. - Relative humidity: 60-80%

[0275] - CO2: 500 ppm

[0276] - Density: 50-18 heads / m² 2

[0277] Light treatments

[0278] The lighting used is the REDT 680 developed by RED Horticulture. This lighting allows control of 4 colors.

[0279] Before installing the light treatments, the light intensity was measured and adjusted at the plant's crown. An Apogee MQ-500 spectroradiometer was used to verify the light intensities.

[0280] The wavelengths of the colors blue, green, red, and far-red have been defined as follows:

[0281] - Blue: 400-500 nm

[0282] - Green: 500-600 nm

[0283] - Red: 600-700 nm

[0284] - Far red: 700-800 nm

[0285] To verify the spectral qualities, a PG200N spectroradiometer from UPRtek was used.

[0286] Characteristics of light treatments - Photoperiod: 16h

[0287] Luminous intensity: 130 pmol.m' 2 .s' 1

[0288] DLI (Daily light integral): 7.5 mol.m' 2 .s' 1 Spectral quality (B means blue, G means green, R means red and FR means far-red, different phases are separated by the sign "-"; the numbers indicate a light intensity distribution):

[0289] Treatment 1: 15B / 15G / 63R / 7FR 14h

[0290] . Treatment

[0291]

[0292] . Treatment 3: 15B / 15G / 63R / 7FR 5h

[0293]

[0294] 15B / 15G / 63R / 7FR 2h (20% increase in luminous intensity for the 100R phase so that the luminous intensity is 156 pmol.m') 2 .s' 1 )

[0295] For example, "15B / 15G / 63R / 7FR 14h" denotes a 14-hour multispectral phase during which 15% of the light intensity is blue, 15% of the light intensity is green, 63% of the light intensity is red, and 7% of the light intensity is far-red.

[0296]

[0297] Morphological measurements

[0298] - Sample: 8 plants per variety and per treatment

[0299] - Duration: 4 weeks of measurement

[0300] Plant monitoring

[0301] Frequency :

[0302] - First week: 1 time, 7 days after lighting

[0303] - Weeks 2, 3 and 4: 2 times a week, complete monitoring - every day for plant height and number of leaves

[0304] Total height (cm)

[0305] Measure using a ruler from the base of the rock wool cube to the top of the plant.

[0306] Number of sheets

[0307] Count the number of fully unfurled leaves after the cotyledons. By "fully unfurled," we mean flat leaves longer than 1.5 cm.

[0308]

[0309] - Mass of the plant cut at the base, measured on a precision scale.

[0310] - Mass of the plant's leaves (including the petiole), measured on a precision balance. - Mass of the plant's stem, measured on a precision balance. Generally speaking, fresh weight corresponds to the mass of a living being or a sample of living beings, thus including their water content.

[0311]

[0312] Statistical analyses were performed on the data obtained for all plants in each replicate and for each of the measured criteria. These analyses were processed using the R software. The data were analyzed with a one-way analysis of variance (ANOVA, p < 0.05) (light processing). If significant differences were found between the variances studied, the means were then compared pairwise using Tukey's test (Honest Significant Difference, HSD, p < 0.05). When the residuals did not meet the conditions of normality and homoscedasticity, the Kruskal-Wallis test was performed, followed by the Wilcoxon-Mann-Whitney test (p < 0.05).

[0313] Results

[0314] Effects of different light treatments on the growth and fresh weight of young tomato plants

[0315] Figures 5a and 5b show the impact of the light spectrum emitted by LED lighting on the height of the first head of tomato seedlings, respectively for the Xaverius, AX variety and the Brioso, RZ variety, measured at 34, 41, 48, 52, and 55 days post-sowing. The light treatments are indicated by the symbols: (T1), (T2), (T3). Significance is indicated by letters following a Tukey test (p<0.05). Figures 5a and 5b show, for each treatment, the change in height of the first head in cm of the seedlings over time.

[0316] The height of the first head of the plants was significantly impacted by the light treatment. A variety-dependent effect was observed. 52 days after sowing, for the Xaverius variety, plants in treatment 3 were significantly smaller by 12.5% ​​and 19% compared to treatments 1 and 2, respectively. Treatments 2 and 3 showed no significant difference. For the Brioso variety, only treatments 3 and 2 showed a significant difference, with a height reduction of 16.2% for treatment 3.

[0317] Figures 5c and 5d show the impact of the light spectrum emitted by LED lighting on the height of the second head of tomato seedlings, respectively for the Xaverius, AX variety and the Brioso, RZ variety, measured at 34, 41, 48, 52, and 55 days post-sowing. The light treatments are indicated by the symbols: (T1), (T2), (T3). Significance is indicated by letters following a Tukey test (p<0.05). Figures 5c and 5d show, for each treatment, the change in height of the second head in cm of the seedlings over time.

[0318] The height of the second main stem of the plants was significantly affected by the light treatment. For the Xaverius variety, plants in treatment 3 were significantly shorter by 14.9% and 25% compared to treatments 1 and 2, respectively. For the Brioso variety, plants in treatment 3 were 8.8% and 15.2% shorter compared to treatments 1 and 2, respectively. Treatments 2 and 3 showed no significant difference.

[0319] Figures 5e and 5f show the impact of the light spectrum emitted by LED lighting on the leaf growth of the first head of tomato seedlings, respectively for the Xaverius, AX variety and the Brioso, RZ variety, measured 41, 48, and 52 days after sowing. Significance is indicated by letters following a Kruskal-Wallis test (p < 0.05). Figures 5e and 5f show, for each treatment, the change in leaf growth (number of leaves) of the first head of the seedlings over time.

[0320] 52 days after sowing, the first head of the Xaverius variety plants had significantly more leaves (17.1% and 14% more) in treatment 3 compared to treatments 1 and 2. For the Brioso variety, plants in treatment 3 had 14.7% more leaves than plants in treatments 1 and 2, respectively. Treatments 1 and 2 showed no significant difference in leaves between the two varieties.

[0321] Figures 5g and 5h show the impact of the light spectrum emitted by LED lighting on the leaf growth of the second main stem of tomato seedlings, for the varieties Xaverius, AX, and Brioso, RZ, respectively, measured 41, 48, and 52 days after sowing. Significance is indicated by letters following a Kruskal-Wallis test (p<0.05). Figures 5g and 5h show, for each treatment, the change in leaf growth (number of leaves) of the second main stem of the seedlings over time.

[0322] The second head of the Xaverius variety plants had significantly more leaves (10.5% and 12.1%) in treatment 3 compared to treatments 1 and 2. For the Brioso variety, plants in treatment 3 had 7.9% and 10.2% more leaves than plants in treatments 1 and 2, respectively. Treatments 1 and 2 showed no significant difference between the two varieties.

[0323] Figures 5i and 5j show the impact of the light spectrum emitted by LED lighting on the fresh weight of the first head of tomato seedlings, specifically the Xaverius, AX, and Brioso, RZ varieties, measured 41 and 52 days after sowing. Significance is indicated by letters following a Tukey test (p<0.05). Figures 5i and 5j show, for each treatment, the change in fresh weight (in grams) of the first head of the seedlings over time. A varietal effect is observed in the distribution of the fresh weight of the first head. For the Xaverius variety, treatments 2 and 3 show no significant difference. Treatment 1 induces a reduction in fresh biomass production of 23.6% and 33.8% compared to treatments 2 and 3, respectively. For the Brioso variety, treatments 1 and 2 show no significant difference.Treatment 3 induces an increase in fresh biomass production of 19.6% and 21.9% compared to treatments 1 and 2.

[0324] Figures 5k and 51 show the impact of the light spectrum emitted by LED lighting on the fresh weight of the second head of tomato seedlings, for the Xaverius, AX variety and the Brioso, RZ variety, respectively, measured at 41 and 52 days post-sowing. Significance is indicated by letters following a Tukey test (p<0.05). Figures 5k and 51 show, for each treatment, the change in fresh weight in grams of the second head of the seedlings over time.

[0325] The fresh weight of the second head of young tomato plants also highlights a varietal effect. For the Xaverius variety, treatments 2 and 3 showed no significant difference. Treatment 1 induced a reduction in fresh biomass production of 9% and 13% compared to treatments 2 and 3, respectively. For the Brioso variety, treatments 1 and 2 showed no significant difference. Treatment 3 induced an increase in fresh biomass production of 15% and 14% compared to treatments 1 and 2.

[0326] Discussion

[0327] For young tomato plants, growers will most often want to compact the seedlings. This is what treatment 3 allows us to do here.

[0328] Reduced electricity consumption without compromising agronomic performance thanks to the red alternative spectrum

[0329] Treatment 1 is the reference treatment that provides good agronomic performance but is energy-intensive. Thanks to the use of the red dynamic spectrum in treatment 2, electricity consumption is reduced by 7.3% while maintaining the same agronomic performance.

[0330] An increase in agronomic performance with an increase in the light intensity of monochromatic red.

[0331] Treatment 3 (which corresponds to treatment 2 with a 20% increase in light intensity during the 7 hours of 100% red light) provides an additional 10% of artificial light over the total photoperiod, in terms of light intensity (specifically in terms of PPFD, i.e., the photon flux density in the photosynthetically active band received by the plant), compared to the other light treatments. This improves agronomic performance by reducing the growth cycle and also by increasing biomass accumulation, resulting in better plant development.

[0332] Treatment 3 has the same electricity consumption as treatment 1 but significantly increased agronomic performance.

[0333] Conclusion

[0334] It has been demonstrated here that in the absence of any natural light, on young tomato plants, it is possible to use artificial lighting with a monochromatic red spectrum of 660nm at 50% of the total photoperiod, completely avoiding the "red syndrome" phenomenon, provided that it is combined with at least one complementary period (before and / or after) with another polychromatic light including at least one other wavelength in a proportion between 10 and 100%.

[0335] Using a 100% red spectrum over part of the photoperiod:

[0336] - It was observed that agronomic efficiency and therefore development were maintained while reducing electricity consumption if the amount of PAR supplied during the phases was equivalent to the control (i.e. during treatment 1),

[0337] - It has been observed that plant development increases, resulting in better biomass production and an advanced stage of development, if the amount of PAR supplied is increased.

[0338]

[0339] cucumber

[0340] Materials and methods

[0341] This experiment was conducted with young cucumber plants in an indoor growing room at PARC (Photobiologic and Agronomy Research Center). The experiment began on May 2, 2024, and ended on May 29, 2024. Three light treatments were compared.

[0342] Plant material and growing conditions

[0343] Cucumber seeds of two varieties, Skyview (Rijk Zwaan) and Dunavine (Nunhems), were sown in Grodan rockwool plugs and then covered with perlite. After 7 days, the seedlings were transplanted into Grodan rockwool cubes. There were two plants per cube, resulting in a density of 19 plants / m². Light treatments were applied on May 4, 2024. For this trial, each light treatment was repeated twice in the grow room. The grow room was divided into 6 blocks, each corresponding to a specific light treatment. Only plants considered to be non-boundary were measured.

[0344] The climate in the growth chambers was controlled by a Hoogendoorn horticultural climate computer. The conditions were as follows:

[0345] - Day / night temperature: 23 / 22 °C during the first half of the growth cycle, then 22 / 20 °C

[0346] - Relative humidity: 60-80%

[0347] - CO2: 500 ppm

[0348] Light treatments

[0349] The lighting system used was the REDT 680 developed by RED Horticulture. This system allows for the control of four colors. Before installing the light treatments, the light intensity was measured and adjusted at the plant's crown. An Apogee MQ-500 spectroradiometer was used to verify the light intensities.

[0350] The wavelengths of the colors blue, green, red, and far-red have been defined as follows:

[0351] - Blue: 400-500 nm

[0352] - Green: 500-600 nm

[0353] - Red: 600-700 nm

[0354] - Far red: 700-800 nm

[0355] To verify the spectral qualities, a PG200N spectroradiometer from UPRtek was used.

[0356] Characteristics of light treatments

[0357] Photoperiod: 16 hours

[0358] Luminous intensity: 140 pmol.m' 2 .s' 1

[0359] DLI (Daily light integral): 8 mol.m' 2 .s' 1

[0360] Spectral quality (B means blue, G means green, R means red and FR means far-red, different phases are separated by the sign "-"; the numbers indicate a light intensity distribution):

[0361] Treatment 1: 18B / 18G / 57R / 7FR 16h

[0362] . Treatment

[0363]

[0364] Treatment 3: 18B / 18G / 57R / 7FR 6h

[0365]

[0366] 18B / 18G / 57R / 7FR 2h (20% increase in luminous intensity for phase 100R so that the luminous intensity is 168 pmol.m') 2 .s' 1)For example, "18B / 18G / 57R / 7FR 16h" denotes a 16-hour multispectral phase during which 18% of the light intensity is blue, 18% of the light intensity is green, 57% of the light intensity is red and 7% of the light intensity is far-red.

[0367]

[0368] Morphological measurements

[0369] - Sample: 8 plants per variety and per treatment

[0370] - Duration: 4 weeks of measurement

[0371] Plant monitoring

[0372] Frequency :

[0373] - First week: 1 time, 7 days after lighting

[0374] - Weeks 2, 3 and 4: 2 times a week, complete monitoring - every day for plant height and number of leaves

[0375] Total height (cm)

[0376] Measure using a ruler from the base of the rock wool cube to the top of the plant.

[0377] Number of sheets

[0378] Count the number of fully unfurled leaves after the cotyledons. By "fully unfurled," we mean flat leaves longer than 1.5 cm.

[0379] Fresh weight: fresh mass of the plant / leaf / tiqe)

[0380] - Mass of the plant cut at the base, measured on a precision scale.

[0381] - Mass of the plant's leaves (including the petiole), measured on a precision balance. - Mass of the plant's stem, measured on a precision balance.

[0382]

[0383] Statistical analyses were performed on the data obtained for all plants in each replicate and for each of the measured criteria. These analyses were processed using the R software. The data were analyzed with a one-way analysis of variance (ANOVA, p < 0.05) (light processing). If significant differences were found between the variances studied, the means were then compared pairwise using Tukey's test (Honest Significant Difference, HSD, p < 0.05). When the residuals did not meet the conditions of normality and homoscedasticity, the Kruskal-Wallis test was performed, followed by the Wilcoxon-Mann-Whitney test (p < 0.05).

[0384] Results

[0385] Effects of different light treatments on the growth and fresh weight of young cucumber plants

[0386] Figures 6a and 6b show the impact of the light spectrum emitted by LED lighting on the height of cucumber seedlings, respectively of the Dunavine, NU variety and the Skyview, RZ variety, measured at 12, 18, 21, and 27 days post-sowing. The light treatments are indicated by the symbols: (T1), (T2), (T3). Significance is indicated by letters following a Tukey test (p<0.05). Figures 6a and 6b show the change in height (in cm) of the seedlings over time for each treatment.

[0387] Plant height was significantly affected by the light treatment. A variety-dependent effect was observed. 27 days after sowing, for the Dunavine variety, plants in treatment 1 were significantly taller (11.3% and 14.3% taller) compared to treatments 2 and 3, respectively. Treatments 2 and 3 showed no significant difference. For the Skyview variety, plants in treatments 1 and 2 were significantly taller (10.4% taller) than plants in treatment 3.

[0388] Figures 6c and 6d show the impact of the light spectrum emitted by LED lighting on the leaf growth of young cucumber plants, specifically the Dunavine, NU variety and the Skyview, RZ variety, measured 27 days after sowing. Significance is indicated by letters following a Kruskal-Wallis test (p < 0.05). Figures 6c and 6d show, for each treatment, the leaf growth in number of leaves 27 days after sowing.

[0389] As with height, a variety-dependent effect is observed for the number of leaves. Plants of the Dunavine variety have significantly more leaves in treatment 3 compared to treatments 1 and 2, which show no difference. For Skyview, plants in treatment 2 have 8.1% more leaves than plants in treatment 1. Plants in treatment 3 have 9.2% and 16.6% more leaves than plants in treatments 2 and 1, respectively.

[0390] Figures 6e and 6f show the impact of the light spectrum emitted by LED lighting on the fresh weight of cucumber seedlings, specifically the Dunavine, NU variety and the Skyview, RZ variety, measured 27 days after sowing. Significance is indicated by letters following a Tukey test (p<0.05). Figures 6e and 6f show, for each treatment, the fresh weight of the seedlings in grams 27 days after sowing.

[0391] No significant varietal effect was observed for the fresh weight of young cucumber plants. For both varieties, plants in treatment 3 had a higher fresh weight compared to plants in treatments 1 and 2, with no significant difference between them. Plants in treatment 3 were therefore 26.7% and 18.6% heavier compared to plants in treatments 2 and 1 for Dunavine, and 13.3% and 16.8% heavier for Skyview.

[0392] Discussion

[0393] For young cucumber plants, depending on the producers and environmental conditions, some will want to compact the young plants and others will want to lengthen them.

[0394] Reduced electricity consumption without compromising agronomic performance thanks to the red alternative spectrum

[0395] Treatment 1 is the reference treatment, which provides good agronomic performance but is energy-intensive. Thanks to the use of the red dynamic spectrum in treatment 2, electricity consumption is reduced by 7.3% while maintaining the same agronomic performance. In some cases, such as the number of leaves for the Skyview variety, agronomic performance was increased.

[0396] An increase in agronomic performance with increased light intensity of red monochromatic light

[0397] Treatment 3 (which corresponds to treatment 2 with a 20% increase in light intensity during the 8 hours of 100% red light) provides an additional 10% of artificial light over the total photoperiod, in terms of light intensity (specifically in terms of PPFD, i.e., the photon flux density in the photosynthetically active band received by the plant), compared to the other light treatments. This improves agronomic performance by reducing the growth cycle and also by increasing biomass accumulation, resulting in better plant development.

[0398] Treatment 3 has the same electricity consumption as treatment 1 but significantly increased agronomic performance.

[0399] Conclusion

[0400] It has been demonstrated here that in the absence of any natural light, on young cucumber plants, it is possible to use artificial lighting with a monochromatic red spectrum of 660nm at 50% of the total photoperiod, completely avoiding the "red syndrome" phenomenon, provided that it is combined with at least one complementary period (before and / or after) with another polychromatic light comprising at least one other wavelength in a proportion between 10 and 100%.

[0401] Using a 100% red spectrum over part of the photoperiod:

[0402] - It was observed that agronomic efficiency and therefore development were maintained while reducing electricity consumption if the amount of PAR supplied during the phases was equivalent to the control (i.e. during treatment 1).

[0403] - It has been observed that plant development increases, resulting in better biomass production and an advanced stage of development, if the amount of PAR supplied is increased.

[0404]

[0405] Materials and methods

[0406] This experiment was conducted with young pepper plants in an indoor growing room at PARC (Photobiologic and Agronomy Research Center). The experiment began on August 1, 2024, and ended on September 18, 2024. Three light treatments were compared.

[0407] Plant material and growing conditions

[0408] Pepper seeds of two varieties, Alzamora (Rijk Zwaan) and Levente (Enza Zaden), were sown in Grodan rockwool plugs and then covered with perlite. After two weeks, the plants were transplanted into Grodan rockwool cubes. There was one plant per cube, and the planting density was initially set at 100 plants. 2 to 22 plants. m' 2 after spacing. The light treatments were applied on August 6, 2024.

[0409] For this experiment, each light treatment was repeated twice in the space. The growth chamber was divided into 6 blocks. Each block corresponded to one light treatment. Only plants considered non-boundary were measured.

[0410] The climate in the growth chambers was controlled by a Hoogendoorn horticultural climate computer. The conditions were as follows:

[0411] - Day / night temperature: 23 / 21 °C for the first 3 weeks, then 21.5 / 19.5 °C. - Relative humidity: 60-80%.

[0412] - CO2: 500 ppm

[0413] Light treatments

[0414] The lighting system used was the REDT 680 developed by RED Horticulture. This system allows for the control of four colors. Before installing the light treatments, the light intensity was measured and adjusted at the plant's crown. An Apogee MQ-500 spectroradiometer was used to verify the light intensities.

[0415] The wavelengths of the colors blue, green, red, and far-red have been defined as follows:

[0416] - Blue: 400-500 nm

[0417] - Green: 500-600 nm

[0418] - Red: 600-700 nm

[0419] - Far red: 700-800 nm

[0420] To verify the spectral qualities, we used a PG200N spectroradiometer from UPRtek.

[0421] Characteristics of light treatments - Photoperiod: 14h

[0422] Luminous intensity: 140 pmol.m' 2 .s' 1

[0423] DLI (Daily light integral): 7 mol.m' 2 .s' 1

[0424] Spectral quality (B means blue, G means green, R means red and FR means far-red, different phases are separated by the sign "-"; the numbers indicate a light intensity distribution):

[0425] Treatment 1: 15B / 15G / 63R / 7FR 14h

[0426] . Treatment

[0427]

[0428] . Treatment 3: 15B / 15G / 63R / 7FR 5h

[0429]

[0430] 15B / 15G / 63R / 7FR 2h (20% increase in luminous intensity for the 100R phase so that the luminous intensity is 168 pmol.m') 2 .s' 1 )

[0431]

[0432] Morphological measurements

[0433] - Sample: 8 plants per variety and per treatment

[0434] - Duration: 4 weeks of measurements

[0435] Plant monitoring

[0436] Frequency :

[0437] - First week: 1 time, 7 days after lighting

[0438] - Weeks 2, 3 and 4: 2 times per week, complete monitoring - every day for plant height and number of leaves.

[0439] Total height (cm)

[0440] Measure using a ruler from the base of the rockwool cube to the top of the plant. Number of

[0441] Count the number of fully unfurled leaves after the cotyledons. By "fully unfurled," we mean flat leaves longer than 1.5 cm.

[0442] Fresh weight: fresh mass of the plant / leaf / tiqe ( )

[0443] - Mass of the plant cut at the base, measured on a precision scale.

[0444] - Mass of the plant's leaves (including the petiole), measured on a precision balance. - Mass of the plant's stem, measured on a precision balance.

[0445]

[0446] Statistical analyses were performed on the data obtained for all plants in each replicate and for each of the measured criteria. These analyses were processed using the R software. The data were analyzed with a one-way analysis of variance (ANOVA, p < 0.05) (light processing). If significant differences were found between the variances studied, the means were then compared pairwise using Tukey's test (Honest Significant Difference, HSD, p < 0.05). When the residuals did not meet the conditions of normality and homoscedasticity, the Kruskal-Wallis test was performed, followed by the Wilcoxon-Mann-Whitney test (p < 0.05).

[0447] Results

[0448] Effects of different light treatments on the growth and fresh weight of young pepper plants

[0449] Figures 7a and 7b show the impact of the light spectrum emitted by LED lighting on the height of young pepper plants, specifically the Levente and Alazamora varieties, measured at 20, 27, 29, 34, 41, and 48 days post-sowing. Significance is indicated by letters following a Tukey's test (p < 0.05). Figures 7a and 7b show, for each treatment, the change in height (in cm) of the young pepper plants over time.

[0450] Plant height was significantly impacted by light treatment, with the same trend observed for both varieties. At the final date, 48 days after sowing, plants in treatment 3 were significantly shorter by 7.3% and 4.1% compared to treatments 1 and 2, respectively, for the Levente variety. For the Alzamora variety, treatment 3 reduced height by 4.5% compared to treatments 1 and 2.

[0451] Figures 7c and 7d show the impact of the light spectrum emitted by LED lighting on the leaf growth of young pepper plants, specifically the Levente and Alazamora varieties, measured at 20, 27, 29, 34, 41, and 48 days post-sowing. Significance is indicated by letters following a Kruskal-Wallis test (p < 0.05). Figures 7c and 7d show, for each treatment, the change in leaf growth (number of leaves) over time.

[0452] The Levente variety plants had significantly more leaves in treatment 3 compared to treatments 1 and 2 (6.7%). For Alzamora, plants in treatment 3 had 10.2% and 16.5% more leaves than plants in treatments 1 and 2, respectively. Treatments 1 and 2 showed no significant difference between the two varieties.

[0453] Figures 7e and 7f show the impact of the light spectrum emitted by LED lighting on the total fresh weight of young pepper plants, specifically the Levente and Alazamora varieties, and its distribution measured 48 days after sowing. Significance is indicated by letters following a Tukey's test (p<0.05). Figures 7e and 7f each illustrate the total fresh weight, leaf weight, and stem weight for each treatment at 48 days after sowing.

[0454] The plants from treatments 1 and 2 showed no significant difference in total fresh weight for either variety. For Alzamora, treatment 3 resulted in a 9.7% and 13.8% increase in total weight compared to treatments 1 and 2. For Levente, treatment 3 only resulted in a 9.5% increase in total fresh weight compared to treatment 2.

[0455] Discussion

[0456] For young pepper plants, growers will most often want to compact the young plants. This is what treatment 3 allows here.

[0457] Reduced electricity consumption without compromising agronomic performance thanks to the red alternative spectrum

[0458] Treatment 1 is the reference treatment that provides good agronomic performance but is energy-intensive. Thanks to the use of the red dynamic spectrum in treatment 2, electricity consumption is reduced by 7.3% while maintaining the same agronomic performance.

[0459] An increase in agronomic performance with increased light intensity of red monochromatic light

[0460] Treatment 3, with a 20% increase in light intensity during the 7 hours of 100% red light, provides an additional 10% of artificial light over the total photoperiod, in terms of light intensity (specifically in terms of PPFD, i.e., photon flux density in the photosynthetically active band received by the plant), compared to the other light treatments. This improves agronomic performance by reducing the growth cycle and also promotes better biomass accumulation, resulting in improved plant development.

[0461] Treatment 3 has the same electricity consumption as treatment 1 but significantly increased agronomic performance.

[0462] Conclusion

[0463] It has been demonstrated here that in the absence of any natural light, on young pepper plants, it is possible to use artificial lighting with a monochromatic red spectrum of 660nm, 50% of the total photoperiod, completely avoiding the "red syndrome" phenomenon, provided that it is combined with at least one complementary period (before and / or after) with another polychromatic light including at least one other wavelength in a proportion between 10 and 100%.

[0464] Using a 100% red spectrum over part of the photoperiod:

[0465] - It was observed that agronomic efficiency and therefore development were maintained while reducing electricity consumption if the amount of PAR supplied during the phases was equivalent to the control (i.e. during treatment 1).

[0466] - It has been observed that plant development increases, resulting in better biomass production and an advanced stage of development, if the amount of PAR supplied is increased.

Claims

1. 45 DEMANDS 1. A method for artificially illuminating a plant to promote plant development (100), the method comprising a step of emitting radiation towards the plant (100) during a period called the photoperiod, the emission step comprising at least the following two distinct phases: a) a red phase representing at least 10% of the photoperiod, during which only primary radiation is artificially emitted, the primary radiation being red; b) a multispectral phase, during which secondary radiations are artificially emitted, the secondary radiations comprising at least two radiations from among blue radiation, green radiation, red radiation and far-red radiation.

2. A method according to claim 1, wherein the emission step does not include a phase, called monospectral, in which only radiation of a specific color is artificially emitted, other than said red phase.

3. A method according to any one of claims 1 and 2, wherein the red phase represents less than 90% of the photoperiod.

4. A method according to any one of claims 1 to 3, wherein the secondary radiation comprises a first radiation which is red radiation and at least a second radiation which is radiation among blue radiation, green radiation and far-red radiation, at least 5% of a total luminous intensity of the secondary radiation corresponding to the at least a second radiation.

5. A method according to any one of claims 1 to 4, wherein the secondary radiation comprises at least three radiations from blue radiation, green radiation, red radiation and far-red radiation.

6. A method according to claim 5, wherein the secondary radiation comprises blue radiation, green radiation, red radiation and far-red radiation.

7. A method according to claim 6, wherein 5 to 30% of the total luminous intensity of the secondary radiation corresponds to blue radiation, 5 to 30% of the total luminous intensity of the secondary radiation corresponds to green radiation, and 40 to 95% of the total luminous intensity of the secondary radiation corresponds to 46 Red radiation and 1 to 20% of the total light intensity of secondary radiation correspond to far-red radiation.

8. A method according to any one of claims 1 to 7, wherein red radiation is radiation with a wavelength between 600 and 700 nm.

9. A method according to any one of claims 1 to 8, wherein blue radiation is radiation with a wavelength between 400 and 500 nm, green radiation is radiation with a wavelength between 500 and 600 nm and far-red radiation is radiation with a wavelength between 700 and 800 nm.

10. A method according to any one of claims 1 to 9, wherein a luminous intensity of the primary radiation is greater than or equal to a total luminous intensity of all the secondary radiation(s).

11. A method according to claim 10, wherein the luminous intensity of the primary radiation is at least 10% greater than the total luminous intensity of all the secondary radiation(s).

12. A method according to any one of claims 1 to 11, wherein the emission step comprises a first multispectral phase implemented before the red phase and a second multispectral phase implemented after the red phase.

13. A method according to any one of claims 1 to 12, wherein a luminous intensity of the primary radiation and / or a luminous intensity of the secondary radiation and / or a duration of the photoperiod and / or a duration of one or each of the phases is modulated according to parameters relating to the development of the plant and / or parameters relating to the environment of the plant.

14. Device (1) for artificially lighting a plant in order to promote plant development (100) comprising at least one primary lighting unit (10), at least two secondary lighting units (20) and data processing means (15) configured to control the lighting units (10, 20) to implement the method according to any one of claims 1 to 13.

15. Device according to claim 14, wherein the data processing means (15) are configured to vary a luminous intensity of the primary radiation and / or a luminous intensity of the secondary radiation and / or a duration of the photoperiod and / or a duration of one or each of the phases as a function of parameters47 relating to plant development and / or parameters relating to the plant environment.

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