Method and device for artificially illuminating a plant in order to promote plant growth

Abstract

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 radiation is artificially emitted, the secondary radiation comprising at least two radiations from among blue radiation, green radiation, red radiation, and far-red radiation. Figure for the abstract: Figure 1.

Description

Title of the invention: Method and device for artificially illuminating a plant to promote plant growth. FIELD OF THE INVENTION

[0001] 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. STATE OF THE ART

[0002] Artificial lighting devices can be used to grow plants; these devices are called horticultural lighting. It is known that red lighting promotes the most photosynthesis. Red photons are indeed the most readily absorbed and assimilated by plants.

[0003] However, when plants are illuminated by monochromatic red light, we observe, among other things, plant weakening, a decrease in agronomic yield, and significant etiolation. This phenomenon is called the "red syndrome".

[0004] Horticultural lighting devices are known that include LEDs (light-emitting diodes) designed to emit red light and one or more other colors of light, thus preventing "red syndrome." In particular, to allow operators to see in a growth chamber, these devices continuously emit white light in addition to the red light. However, these devices consume a significant amount of energy.

[0005] There is therefore a need for an artificial lighting process for a plant in order to promote plant development which allows for good agronomic yield while limiting energy consumption. Description of the invention

[0006] One object of the invention is to provide a method and device for artificial lighting of a plant in order to promote plant development which allows for good agronomic yield while limiting energy consumption.

[0007] According to a first aspect, a method of artificially illuminating a plant is proposed in order to promote plant development, the method comprising a step of emitting radiation towards the plant during a period called the photoperiod, the emission step comprising at least the following two distinct phases:

[0008] a) a red phase representing at least 10% of the photoperiod, during which only primary radiation is artificially emitted, the primary radiation being red;

[0009] 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.

[0010] According to advantageous and non-limiting features, taken alone or in any combination:

[0011] - the red phase represents less than 90% of the photoperiod;

[0012] - the red phase represents at least 40% of the photoperiod;

[0013] - secondary radiation includes primary radiation which is a red radiation and at least one second radiation which is one of blue radiation, green radiation and far-red radiation, at least 5% of a total luminous intensity of the secondary radiations corresponding to the at least one second radiation;

[0014] - the secondary radiation includes blue radiation, radiation green, red radiation and far-red radiation;

[0015] - 5 to 30% of the total luminous intensity of secondary radiation correspond 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;

[0016] - 15% of the total luminous 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;

[0017] - 18% of the total luminous intensity of secondary radiation corresponds In 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;

[0018] - 15% of the total luminous intensity of secondary radiation corresponds In blue light, 15% of the total light intensity of secondary radiation corresponds to green light, 60% of the light intensity total 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;

[0019] - red radiation is radiation with a wavelength between 600 and 700 nm;

[0020] - 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;

[0021] - a luminous intensity of the primary radiation is greater than or equal to a total luminous intensity of all secondary radiation(s);

[0022] - the luminous intensity of the primary radiation is at least 10% greater than the total luminous intensity of all the secondary radiation(s);

[0023] - the multispectral phase is implemented after the red phase;

[0024] - the multispectral phase is implemented before the red phase;

[0025] - the emission step includes a first multispectral phase implemented before the red phase and a second multispectral phase implemented after the red phase;

[0026] - a luminous intensity of the primary radiation and / or a luminous 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 plant development and / or parameters relating to the plant environment;

[0027] - the first multispectral phase lasts 5 hours, the red phase lasts 7 hours and the The second multispectral phase lasts 2 hours, the plant being preferably a young tomato plant or a young pepper plant;

[0028] - the first multispectral phase lasts 6 hours, the red phase lasts 8 hours and the The second multispectral phase lasts 2 hours, the plant being preferably a young cucumber plant, a tomato plant or a cucumber plant.

[0029] 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.

[0030] 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. DESCRIPTION OF THE FIGURES

[0031] 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:

[0032] - [Fig.1] schematically represents an artificial lighting device;

[0033] - [Fig.2] represents the steps of an artificial lighting process;

[0034] - Figures [Fig. 3a], [Fig. 3b], [Fig. 3c], [Fig. 3d], [Fig. 3e] show the results of the implementation implementation of the process on cucumber plants;

[0035] - Figures [Fig. 4a], [Fig. 4b], [Fig. 4c] show results of the implementation of the process on tomato plants;

[0036] - the [Fig.5a], [Fig.5b], [Fig.5c], [Fig.5d], [Fig.5e], [Fig.5f], [Fig.5g], [Fig.5h], [Fig.5i], [Fig.5j], [Fig.5k], [Fig.51] show results of the implementation of the process on young tomato plants;

[0037] - Figures [Fig. 6a], [Fig. 6b], [Fig. 6c], [Fig. 6d], [Fig. 6e], [Fig. 6f] show results of the implementation of the process on young cucumber plants;

[0038] - Figures [Fig.7a], [Fig.7b], [Fig.7c], [Fig.7d], [Fig.7e], [Fig.7f] show results of the implementation of the process on young pepper plants. DETAILED DESCRIPTION OF THE INVENTION

[0039] 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.

[0040] The term "plant" refers to any type of plant, at any stage of its development. Specifically, a plant may be in the seedling stage, the young plant stage, or the plant stage (a plant is at a more advanced stage of development than a young plant). A plant may be a seedling, a young plant, or a vegetable plant (for example, cucumber, pepper, tomato), a fruit plant, a flowering plant (for example, cannabis or chrysanthemum), etc.

[0041] A plant grown indoors generally needs additional light to compensate for a lack, or even a total absence, of natural light. This is the case, for example, of a plant placed in a grow room that does not benefit from natural lighting. In these situations, it is necessary to artificially illuminate the plant to allow its development, using appropriately positioned artificial light sources.

[0042] Natural lighting is defined as lighting produced by the sun, whether through direct solar radiation and / or diffuse solar radiation. Generally, natural lighting therefore results from the combination of direct and diffuse solar radiation.

[0043] By radiation, we mean a set 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.

[0044] A plant grown in a greenhouse benefits from natural lighting that is more or less similar to that which it would receive if grown outdoors. However, to optimize plant development, it is advisable to supplement this natural lighting, which depends in particular on sunlight, with appropriate artificial lighting.

[0045] Artificial lighting means 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.

[0046] 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.

[0047] When a plant is in a location with natural light (for example, a greenhouse), it is subjected to overall lighting consisting of a combination of natural and artificial light. In order to carry out the photosynthesis necessary for its growth, the plant therefore has access to radiant energy provided by the radiation produced by this overall lighting.

[0048] A plant is illuminated, artificially and / or naturally, during a day for a period called the photoperiod. Outside of the photoperiod, the plant is not illuminated by either artificial or natural light. During the photoperiod, the plant may be illuminated artificially and / or naturally. Thus, if it is nighttime or if the plant is in a room without natural light and is artificially illuminated, it is in the 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 phase 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 to be a single, continuous block and not interrupted 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.

[0049] In photosynthesis, not all radiation is equal. The radiation useful for photosynthesis is radiation with wavelengths ranging from approximately 400 to 700 nanometers (nm). This is photosynthetically active radiation (PAR). The 400 to 700 nm range is also referred to as the photosynthetically active wavelength band.

[0050] Radiation received by a plant in a wavelength range outside the 400-700 nm band, and in particular 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 approximately to the visible spectrum; that is to say, the radiation emitted in this wavelength band corresponds to light visible to the human eye.

[0051] In particular, blue radiation, green radiation, red radiation and far-red radiation are distinguished.

[0052] Advantageously, blue radiation is radiation with a wavelength between 400 and 500 nm.

[0053] Advantageously, green radiation is radiation with a wavelength between 500 and 600 nm

[0054] Advantageously, red radiation is radiation with a wavelength between 600 and 700 nm.

[0055] Advantageously, far-red radiation is radiation with a wavelength between 700 and 800 nm.

[0056] 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 in large quantities.

[0057] The amount of light received by the plant advantageously corresponds to a photon flux density in the photosynthetically active band received by the plant. The received photon flux density is expressed in pmol.m².s⁻¹. The received photon flux density is the number of photons, expressed here in pmol, received per unit area of ​​the plant, expressed in square meters (m²), and per unit time expressed in seconds.

[0058] 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·s.

[0059] 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 flux of photon quantifies the light emitted towards the plant (we are looking at it from the point of view of artificial and / or natural light sources).

[0060] Generally speaking, the term luminous intensity of radiation or a set of radiations will be used to encompass the notions of the quantity of light received by the plant and the photon flux. Thus, when referring to luminous intensity, this can designate the quantity of light received by the plant and / or the photon flux of radiation emitted towards the plant.

[0061] 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 may, for example, include red radiation, blue radiation, and green radiation. To quantify the proportion of each radiation within the set, a percentage of the photon flux for each radiation can be used. For example, the set of emitted radiations may be considered to be characterized by a total photon flux. The set of radiations may 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.

[0062] Other parameters influence the phenomenon of photosynthesis, such as ambient temperature, leaf temperature, ambient carbon dioxide level, 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.

[0063] The saturation point of a plant, or saturation threshold, is generally expressed in pmol.m².s⁻¹ and 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, i.e., 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.

[0064] 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.

[0065] In cases where the plant does not benefit from natural light, artificial lighting allows the plant to develop. In particular, the artificial lighting method of the invention allows for optimized plant growth.

[0066] In cases where the plant also benefits from natural light, advantageously, artificial lighting allows for adequate supplementation of 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 maximal and strictly below the plant's saturation threshold. Artificial lighting is particularly useful for compensating for the lack of sunlight in winter or on particularly cloudy days. Artificial lighting can also, for example, increase the length of days, that is, provide light to the cultivated plant 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. Device

[0067] With reference to [Fig.1], an artificial lighting device 1 for a plant 100 is proposed in order to promote the development of the plant 100.

[0068] Device 1 comprises at least one primary lighting unit 10 and at least two secondary lighting units 20.

[0069] The primary lighting unit 10 is configured to emit primary radiation in a primary wavelength band.

[0070] The primary lighting unit 10 is configured to emit red radiation.

[0071] 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 a 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 specifically, the first secondary wavelength band is different from the second secondary wavelength band, so that the first secondary radiation is 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 radiation 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. Of Preferably, the first secondary lighting unit 20a is configured to emit a first red secondary beam, the second secondary lighting unit 20b is configured to emit a second blue secondary beam, and a third secondary lighting unit 20c (not shown in the figures) is configured to emit a third far-red secondary beam.

[0076] The 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 comprises at least one light-emitting diode (LED). Some or all of the lighting units may comprise 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, an LED offers, in particular, 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 blue secondary radiation includes a blue monochromatic LED.

[0081] According to one embodiment, a secondary lighting unit 20 configured to emit far-red secondary radiation includes a far-red monochromatic LED.

[0082] According to one embodiment, a secondary lighting unit 20 configured to emit green secondary radiation comprises a monochromatic green LED. Alternatively, and advantageously, a secondary lighting unit 20 configured to emit green secondary radiation comprises a polychromatic LED producing a white color and emitting between 25 and 80% of its radiation in the green range. Such an LED notably allows for a higher photonic efficiency than that which would be possible with a monochromatic light-emitting diode producing green light.

[0083] Each lighting unit 10, 20 is adapted to emit radiation towards at least one plant 100 in a given wavelength band. Therefore, each lighting unit 10, 20 is adapted to be arranged opposite at least one plant 100 so that the plant receives the radiation emitted by each unit when the unit is in operation.

[0084] 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.

[0085] 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.

[0086] Device 1 includes data processing means 15 configured to control lighting units 10, 20 so as to implement an artificial lighting process as will be described later.

[0087] The data processing means 15 are advantageously configured to allow 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. According to an embodiment in which one or more 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.

[0088] 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.

[0089] 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 luminous 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.

[0090] 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 more or less 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.

[0091] For example, the 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.

[0092] Parameters relating to the plant's environment may, for example, include a humidity level, a light intensity of natural (i.e. solar) radiation, a temperature, etc.

[0093] 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 units lighting 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. Process

[0094] With reference to [Fig.2], a method of artificially lighting a plant is proposed in order to promote the development of the plant 100.

[0095] By artificial lighting method, it is understood that the lighting method consists exclusively of the emission of artificial radiation. However, the plant may be in a location where natural radiation penetrates. Thus, the artificial lighting method can be combined with natural lighting of the plant. The lighting method can also be implemented in a location where the plant is not naturally lit. The method allows for an increase in agronomic yield while limiting electricity consumption in both cases (whether or not natural lighting is added).

[0096] The process includes a step of emitting radiation towards the plant 100 during one photoperiod. By "towards the plant," it is understood that the radiation is emitted in such a way that the plant receives the radiation. In other words, the lighting units are arranged facing the plant so that the plant benefits from the radiation when the unit(s) emit it.

[0097] The emission step comprises at least two distinct phases. By distinct, it is understood that the two phases do not overlap temporally.

[0098] Furthermore, the phases of the emission stage are consecutive and are not separated by a phase without artificial lighting. By phase without artificial lighting, we mean a phase of substantial duration, that is, lasting more than approximately 30 minutes. Consequently, the phases of the emission stage are considered to be consecutive even if they are separated by a short phase without artificial lighting, i.e., a phase of less than 30 minutes without artificial lighting.

[0099] Furthermore, advantageously, there is only one emission phase during which the plant receives artificial lighting in a 24-hour period. During the remainder of the day, which does not correspond to the emission phase, the plant is not subjected to artificial lighting. 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 is equal to 100% of the photoperiod.

[0100] 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 that the plant benefits from, is red.

[0101] The red phase corresponds to a phase during which the plant 100 receives artificial red light. In other words, the red phase corresponds to a phase during which at least one primary lighting unit 10 emits artificial red light towards the plant 100. Red is preferably understood to mean light with a wavelength between 600 and 700 nm.

[0102] Red radiation is the radiation that allows for the most photosynthesis. Red photons are indeed the best absorbed and assimilated by plants.

[0103] 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.

[0104] Advantageously, the red phase lasts at least 30% of the photoperiod, preferably at least 40%, or at least 50%, or at least 60%, or at least 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 could lead to "red syndrome." Thus, preferably, the red phase lasts less than 90% of the photoperiod.

[0105] Advantageously, by "only primary radiation is artificially emitted, the primary radiation being red radiation," it is understood 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.

[0106] 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, 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 may mean in practice that a very small percentage corresponds to 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.

[0107] Light intensity can correspond to the amount of light received by the plant corresponding to the primary radiation or to the photon flux of the radiation Primary. Indeed, whether we measure the amount of light received by the plant corresponding to primary radiation (preferably in pmol.m².s⁻¹) or the photon flux of primary radiation (preferably in pmol.s⁻¹), we will advantageously have at least 100% of each of these quantities corresponding to red radiation. By the amount of light received by the plant corresponding to primary radiation, we mean that we are not considering the amount of light received by the plant corresponding to other radiations such as natural radiation. If 100% of the amount 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.

[0108] The red phase aims to optimize the phenomenon of photosynthesis and promotes plant growth 100.

[0109] The emission step of the process further includes a multispectral phase (b) during which secondary radiation is emitted. The 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 prevents the occurrence of the "red syndrome" phenomenon.

[0110] Secondary radiation is purely artificial.

[0111] It is understood from the existence of the multispectral phase that the red phase does not last 100% of the photoperiod.

[0112] Preferably, the multispectral phase represents at least 10% of the photoperiod. Advantageously, the multispectral phase represents less than 90% of the photoperiod.

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

[0114] Advantageously, at least 5% of the total luminous intensity of the secondary radiation corresponds to at least one second radiation. In other words, less than 95% of the total luminous intensity of the secondary radiation corresponds to the first radiation, which is red.

[0115] The total luminous intensity of the secondary radiation(s) corresponds to the luminous intensity of all the secondary radiation. The intensity Luminous flux can correspond to the amount of light received by the plant from secondary radiation or to the photon flux of all secondary radiation. Indeed, whether we measure the amount of light received by the plant from secondary radiation (preferably in pmol.m².s⁻¹) or the photon flux of all secondary radiation (preferably in pmol.s⁻¹), at least 5% of each of these quantities will correspond to non-red radiation. By the amount of light received by the plant from secondary radiation, we mean that we are not considering the amount of light received by the plant from other types of radiation, such as natural radiation.If 5% of the amount of light received by the plant corresponding to secondary radiation is blue radiation, then 5% of the photon flux of secondary radiation is blue radiation, and vice versa.

[0116] Advantageously, at least 10%, or even at least 15%, or even at least 20%, of the total luminous intensity of the secondary radiation corresponds to at least one second radiation.

[0117] According to a preferred embodiment, the secondary radiation comprises a first radiation which is red radiation and a second radiation which is blue radiation. This makes it possible to obtain a better agricultural yield while limiting the energy consumption of the device 1.

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

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

[0121] According to 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% of the total secondary radiation intensity corresponds to green radiation, 63% of the total secondary radiation intensity corresponds to red radiation, and 7% of the total secondary radiation intensity corresponds to far-red radiation. This makes it possible to obtain, for a young pepper plant, a young tomato plant, or a tomato plant, a better agronomic yield while limiting electricity consumption.

[0122] According to 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] According to one embodiment, the luminous intensity of the primary radiation is equal to the luminous intensity of all the 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 agronomic yield is maintained while reducing electricity consumption compared to the prior art.

[0125] According to another embodiment, the luminous intensity of the primary radiation is greater than the luminous intensity of all the 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 agronomic yield is obtained with little or no increase in electricity consumption compared to the prior art.

[0126] Advantageously, the total luminous intensity of the primary radiation is at least 10% higher, preferably at least 15% higher, and even more preferably at least 20% higher, than the luminous intensity of all the secondary radiation(s). This makes it possible to obtain a very good agronomic yield with little or no increase in electricity consumption compared to the prior art.

[0127] 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.

[0128] 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 step of the process includes the detection of natural radiation, i.e., solar radiation, and the light intensity of the artificial radiation is adjusted according to this solar radiation. For example, during the red phase, the light intensity of the radiation can be increased or decreased according to the amount of natural red radiation. Alternatively, the duration of the red phase and / or the multispectral phase can be increased or decreased according to the duration of natural lighting (i.e., the length of the day).

[0129] The emission step of the process may comprise only two phases, namely a single red phase and a single multispectral phase. In one embodiment, the red phase is carried out before the multispectral phase (from the perspective of a 24-hour day beginning at midnight and ending at 11:59 p.m.). In another embodiment, the red phase is carried out after the multispectral phase. This can, under certain circumstances, allow for better yield while limiting energy consumption. The choice of carrying out 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.

[0130] The emission step of the process may comprise three phases, namely a single red phase and two multispectral phases. In this case, the emission step of the process includes a multispectral phase implemented before the red phase and a multispectral phase implemented after the red phase. This may, under certain circumstances, allow for better efficiency while limiting energy consumption.

[0131] According to one embodiment, the plant is a young tomato plant or a young pepper plant and the emission step 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. EXAMPLES Example cucumber plant Materials and method

[0133] These two experiments were carried out 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

[0134] Cucumber seeds of two varieties, Roadie (Rijk 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 plants received the same light treatment. The plants were transplanted onto double gutters on Grodan rockwool blocks, in a high wire culture, on January 3, 2024. The planting density was 2.8 plants / m². Light treatments were applied one day later.

[0135] Each light treatment was repeated twice in the space. Each grow room has 5 rows of gutters. The compartment was divided into blocks of 20 m² each. Each block corresponds to one light treatment. Only the plants in the middle row were used for analysis.

[0136] The climate in the growth rooms was controlled by a Hoogendoom horticultural climate computer. The conditions were as follows:

[0137] - Day / Night Temperature: 24 / 19 °C

[0138] - Relative humidity: 70-85%

[0139] - CO2: 750 ppm

[0140] The air temperature was recorded in each compartment and showed no significant difference. Light treatment

[0141] The lighting used is the REDT 680 developed by RED Horticulture. This lighting allows for the control of 4 colors.

[0142] Before the light treatments were implemented, the light intensity was measured and adjusted at the plant head. An Apogee MQ-500 spectroradiometer was used to verify the light intensities.

[0143] The definition of the wavelengths of the colors blue, green, red and far-red is as follows:

[0144] - Blue: 400-500 nm

[0145] - Green: 500-600 nm

[0146] - Red: 600-700 nm

[0147] - Far red: 700-800 nm

[0148] In order to control the spectral qualities, a PG200N spectroradiometer from the brand UPRteka was used. Characteristics of light treatments

[0149] - Photoperiod: 16h

[0150] - Luminous intensity: 315 pmol.m².s⁻¹ ± 25 pmol.m².s⁻¹

[0151] - DLI (Daily light integral): 18 mol.m 2.s 1

[0152] - Spectral quality (B means blue, G means green, R means red and FR means far red, different phases are separated by the symbol « »; the numbers indicate a distribution of light intensity):

[0153] • Treatment 1: 15B / 15G / 60R / 10FR 16h

[0154] • Treatment 2: 15B / 15G / 60R / 10FR 6h 100R 8h 15B / 15G / 60R / 10FR 2h

[0155] • Treatment 3: 15B / 15G / 60R / 10FR 6h 100R 8h 15B / 15G / 60R / 10FR 2h (20% increase in luminous intensity for phase 100R so that the luminous intensity is 378 pmol.m 2.s ')

[0156] • Treatment 4: 5B / 5G / 90R 16h

[0157] For example, "15B / 15G / 60R / 10FR 16h" designates 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. Plant analysis Morphological measurements

[0158] - Sample: 6 plants of the Roadie variety / 6 plants of the Dee Votion variety / 6 Roadie variety plants: 18 plants per method

[0159] - Duration: 13 weeks of measurements Plant monitoring

[0160] Frequency: once a week. Growth, Height (cm)

[0161] Measurement using a meter, from the collar to the head of the plant (first measurement). Then, for the following weeks, the difference in height is measured between the mark made on the growing wire the previous week and the current week (new head height). Number of sheets

[0162] 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. Number of cucumbers

[0163] Number of cucumbers below the last open flower. The cucumber whose last flower is open is also counted. Fruit tracking

[0164] Frequency: once a week Weight (g)

[0165] The weight of the harvested cucumber(s) is measured on a precision balance for each plant checked. Number of fruits harvested

[0166] Counting the number of fruits harvested across the entire plot (even outside of monitored plants). Statistical analysis

[0167] 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 R software. The data were analyzed using 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). Results

[0168] Effects of different light treatments on cucumber production

[0169] Figure 3a 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 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 change in the number of fruits per m² as a function of the number of weeks.

[0170] 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.

[0171] Figure 3c illustrates the impact of the light spectrum emitted by LED lighting on the cumulative yield in kg / m² 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 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 as a function of the number of weeks.

[0172] As with the number of fruits, treatment 4 results in the lowest yield for both varieties. Treatments 1 and 2 are similar in terms of yield. Treatment 3 results in an increase in yield. For Dee Votion, treatment 3 results in a yield increase of 15.8%, 6.9%, and 8.2% compared to treatments 4, 1, and 2, respectively. The same trend is observed for Roadie, where treatment 3 results in a yield increase of 8.6%, 4.9%, and 6% compared to treatments 4, 1, and 2, respectively.

[0173] 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 over 13 weeks of harvest (Dee Votion and Roadie varieties). For each treatment Trt, the cumulative number of fruits harvested per m² is shown in the first column and the cumulative average weight of the harvested fruits in kilograms per m² is shown in the second column. Discussion

[0174] Cucumbers are sold individually and must meet certain size requirements in accordance with the target market. Therefore, for the purposes of this discussion, we will focus primarily on the number of fruits produced. Indeed, the fruits considered for calculating the cumulative fruit yield per square meter are those that meet a specific size requirement.

[0175] A reduction in electricity consumption without altering agronomic performance thanks to the red alternative spectrum

[0176] 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 cucumber pieces produced by 4.7% and 4.4% for Dee Votion and Roadie respectively.

[0177] However, treatment 1 is energy-intensive. For this reason, 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.

[0178] An increase in agronomic performance with increasing light intensity of red monochromatic

[0179] Treatment 3 (which corresponds to treatment 2 with a 20% increase in light intensity during the 8 hours of 100% red light) provides, over the total photoperiod, an additional 10% of artificial light in terms of light intensity (particularly 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 increased agronomic performance with an increase in the number of fruits and yield per m². Conclusion

[0180] It has been demonstrated here that, even in the absence of any natural light, on the production of high wire cucumber, it is possible to use artificial lighting whose spectrum is monochromatic red 660nm at 50% of the total photoperiod duration, totally 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%.

[0181] With the use of a 100% red spectrum over part of the photoperiod:

[0182] - a maintenance of agronomic efficiency and therefore of yield was observed throughout by reducing electrical consumption if the amount of PAR supplied during the phases is equivalent to the control (i.e., during treatment 1),

[0183] - an increase in plant yield was observed, resulting in a better biomass production and an advanced stage of development if the amount of PAR supplied is increased.

[0184] PAR is photosynthetic active radiation. The wavelengths that constitute 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 in its environment. Example tomato plant: Materials and methods

[0185] This experiment was carried out 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. Plant material and growing conditions

[0186] The young tomato plants, Tastyno variety (Gauthier Semence), were received on June 19, 2024, with 2 heads. The plants 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. Light treatments were applied on June 19, 2024.

[0187] 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.

[0188] The climate in the growth chambers was controlled by a Hoogendoom horticultural climate computer. The conditions were as follows:

[0189] - Day / Night Temperature: 24 / 19 °C

[0190] - Relative humidity: 70-85%

[0191] -CO2:750ppm

[0192] The air temperature was recorded in each compartment and showed no significant difference. Light treatments

[0193] The lighting used is the REDT 680 developed by RED Horticulture. This lighting allows control of 4 colors.

[0194] Before installing the light treatments, the light intensity was measured and adjusted at the plant head. An Apogee MQ-500 spectroradiometer was used to verify the light intensities.

[0195] The wavelengths of the colors blue, green, red and far-red have been defined as follows:

[0196] - Blue: 400-500 nm

[0197] - Green: 500-600 nm

[0198] - Red: 600-700 nm

[0199] - Far red: 700-800 nm

[0200] To verify the spectral qualities, a PG200N spectroradiometer from UPRtek was used. Characteristics of light treatments

[0201] - Photoperiod: 16h

[0202] - Luminous intensity: 315 pmol.m².s⁻¹ ± 25 pmol.m².s⁻¹

[0203] - DLI (Daily light integral): 18 mol.m 2.s 1

[0204] - Spectral quality (B means blue, G means green, R means red and FR means far red, different phases are separated by the symbol « »; the numbers indicate a distribution of light intensity):

[0205] • Treatment 1: 15B / 15G / 63R / 7FR 16h

[0206] • Treatment 2: 15B / 15G / 63R / 7FR 6h 100R 8h 15B / 15G / 63R / 7FR 2h

[0207] • Treatment 3: 15B / 15G / 63R / 7FR 6h 100R 8h 15B / 15G / 63R / 7FR 2h (20% increase in luminous intensity for phase 100R so that the luminous intensity is 378 pmol.m 2.s ')

[0208] • Treatment 4: 5B / 5G / 90R 16h

[0209] 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. Plant analysis Morphological measurements

[0210] - Sample: 18 plants per treatment

[0211] - Duration: 13 weeks of measurements Fruit tracking

[0212] Frequency: once a week Weight (g)

[0213] The weight of the harvested tomato(es) is measured on a precision scale for each plant checked. Number of fruits harvested

[0214] Counting the number of fruits harvested across the entire plot (even outside of monitored plants). Statistical analysis

[0215] 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 R software. The data were analyzed using 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). Results

[0216] Effects of different light treatments on tomato production

[0217] Figure 4a illustrates the impact of the light spectrum emitted by LED lighting on the cumulative number of fruits harvested per m² over 13 weeks of harvest. Figure 4a shows, for each treatment, the change in the number of fruits per m² as a function of the number of weeks.

[0218] Treatment 4 results in the lowest number of fruits. Treatments 1 and 2 show similar fruit production, although treatment 2 allows for a slight increase in the number of fruits. Treatment 3 allows for an increase in the number of fruits of 10% and 8.2% compared to treatments 1 and 2, respectively.

[0219] 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 as a function of the number of weeks.

[0220] As with the number of fruits, treatment 4 results in the lowest yield. Treatment 2 provides a slight increase in yield compared to treatment 1. Treatment 3 provides a yield increase of 12.9% and 9.7% compared to treatments 1 and 2, respectively.

[0221] Fig. 4c is a table showing the impact of the light spectrum emitted by lighting LED on the number of fruits harvested and the cumulative yield (kg / m2) over 13 weeks of harvest. For each treatment Trt, the cumulative number of fruits harvested per m2 is indicated in the first column and the cumulative average weight of the harvested fruits in kilograms per m2 is indicated in the second column. Discussion

[0222] A reduction in electricity consumption without altering agronomic performance thanks to the red alternative spectrum

[0223] 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 red dynamic spectrum, treatment 2 reduces consumption by 5% while maintaining the same agronomic performance.

[0224] An increase in agronomic performance with increasing light intensity of red monochromatic

[0225] Treatment 3 (which corresponds to treatment 2 with a 20% increase in light intensity during the 8 hours of 100% red light) provides, over the total photoperiod, an additional 10% of artificial light in terms of light intensity (particularly 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 increased agronomic performance with an increase in the number of fruits and yield per m². Conclusion

[0226] 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%.

[0227] With the use of a 100% red spectrum over part of the photoperiod:

[0228] - it was observed that agronomic efficiency and therefore yield were maintained throughout by reducing electrical consumption if the amount of PAR supplied during the phases is equivalent to the control (i.e., during treatment 1),

[0229] - an increase in plant yield was observed, resulting in a better biomass production and an advanced stage of development if the amount of PAR supplied is increased. Example of a young tomato plant: Materials and methods

[0230] This experiment was carried out with young tomato plants in an indoor growing room at PARC (Photobiologic and Agronomy Research Center). This experiment began on May 28, 2024 and ended on July 22, 2024. Three light treatments were compared. Plant material and growing conditions

[0231] Tomato seeds of two varieties, Brioso (Rijk Zwaan) and Xaverius (Axia), were sown in Grodan rockwool plugs and then covered with perlite. After 2 weeks, they were grafted onto DRO141 rootstock.

[0232] The plants were transplanted into Grodan rockwool cubes on June 24, 2024. There was one plant per cube with two heads. Topping took place on June 24, 2024. The density was reduced from 50 heads / m² to 18 heads / m² after spacing. Light treatments were applied on June 22, 2024.

[0233] For this test, 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.

[0234] The climate in the growth chambers was controlled by a Hoogendoom horticultural climate computer. The conditions were as follows:

[0235] - Day / night temperature: 23 / 21 °C for the first 3 weeks, then 21.5 / 19.5 °C.

[0236] - Relative humidity: 60-80%

[0237] - CO2: 500 ppm

[0238] - Density: 50-18 heads / m2 Light treatments

[0239] The lighting used is the REDT 680 developed by RED Horticulture. This lighting allows control of 4 colors.

[0240] Before installing the light treatments, the light intensity was measured and adjusted at the plant head. An Apogee MQ-500 spectroradiometer was used to verify the light intensities.

[0241] The wavelengths of the colors blue, green, red and far-red have been defined as follows:

[0242] - Blue: 400-500 nm

[0243] - Green: 500-600 nm

[0244] - Red: 600-700 nm

[0245] - Far red: 700-800 nm

[0246] To verify the spectral qualities, a PG200N spectroradiometer from UPRtek was used.

[0247] Characteristics of light treatments - Photoperiod: 16h

[0248] - Luminous intensity: 130 pmol.m².s⁻¹

[0249] - DLI (Daily light integral): 7.5 mol.m 2.s 1

[0250] - Spectral quality (B means blue, G means green, R means red and FR means far red, different phases are separated by the symbol « »; the numbers indicate a distribution of light intensity):

[0251] • Treatment 1: 15B / 15G / 63R / 7FR 14h

[0252] • Treatment 2: 15B / 15G / 63R / 7FR 5h 100R 7h 15B / 15G / 63R / 7FR 2h

[0253] • Treatment 3: 15B / 15G / 63R / 7FR 5h 100R 7h 15B / 15G / 63R / 7FR 2h (20% increase in luminous intensity for phase 100R so that the luminous intensity is 156 pmol.m 2.s ')

[0254] For example, "15B / 15G / 63R / 7FR 14h" designates 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. Plant analysis Morphological measurements

[0255] - Sample: 8 plants per variety and per treatment

[0256] - Duration: 4 weeks of measurement Plant monitoring

[0257] Frequency:

[0258] - First week: 1 time, 7 days after lighting

[0259] - Weeks 2, 3 and 4: 2 times per week, full monitoring - daily for height of the plant and the number of leaves. Total height (cm)

[0260] Measure using a ruler from the base of the rock wool cube to the top of the plant. Number of sheets

[0261] Count the number of fully unfurled leaves after the cotyledons. By "fully unfurled" is meant flat leaves longer than 1.5 cm.

[0262] Fresh weight: fresh mass of the plant / leaf / stem (g)

[0263] - Mass of the plant cut at the collar, measured on a precision balance.

[0264] - Mass of the plant's leaves (including the petiole), measured on a balance of precision.

[0265] - Mass of the plant stem, measured on a precision balance.

[0266] Generally speaking, fresh weight corresponds to the mass of a living being or a sample of living beings, including the water of constitution. Statistical analysis

[0267] 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 R software. The data were analyzed using 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). Results

[0268] Effects of different light treatments on the growth and fresh weight of the young tomato plant

[0269] 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 the height of the first head in cm of the seedlings over time.

[0270] 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.

[0271] 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.

[0272] The height of the second head of the plants was significantly impacted depending on 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.

[0273] 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, expressed as the number of leaves of the first head of the seedlings, over time.

[0274] 52 days after sowing, the first head of the Xaverius variety plants has Treatment 3 showed significantly more leaves (17.1% and 14% more) compared to treatments 1 and 2. For the Brioso variety, plants in treatment 3 had 14.7% and 11.8% more leaves than plants in treatments 1 and 2, respectively. Treatments 1 and 2 showed no significant difference between the two varieties.

[0275] Figures 5g and 5h show the impact of the light spectrum emitted by LED lighting on the leaf growth of the second head of young tomato plants, 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 5g and 5h show, for each treatment, the evolution of leaf growth in number of leaves of the second head of young plants as a function of time.

[0276] The second head of the Xaverius variety plants had significantly more leaves in treatment 3 (10.5% and 12.1%) compared to treatments 1 and 2. For the Brioso variety, plants in treatment 3 had 7.9% more leaves in treatment 1 and 10.2% more leaves in treatment 2 than plants in treatment 1 and 2, respectively. Treatments 1 and 2 showed no significant difference between the two varieties.

[0277] 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, respectively of the Xaverius, AX variety and the Brioso, RZ variety, measured at 41 and 52 days post-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.

[0278] A varietal effect is observed for the distribution of 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.

[0279] 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, respectively for the Xaverius, AX variety and the Brioso, RZ variety, 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.

[0280] 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. Discussion

[0281] For young tomato plants, producers will most often want to compact the young plants. This is what treatment 3 allows here.

[0282] A reduction in electricity consumption without altering agronomic performance thanks to the red alternative spectrum

[0283] 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.

[0284] An increase in agronomic performance with increasing light intensity of red monochromatic.

[0285] Treatment 3 (which corresponds to treatment 2 with a 20% increase in light intensity during the 7 hours of 100% red light) provides, over the total photoperiod, an additional 10% of artificial light in terms of light intensity (particularly 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 development cycle and also by increasing biomass accumulation, resulting in better plant development.

[0286] Treatment 3 has the same electrical consumption as treatment 1 but significantly increased agronomic performance. Conclusion

[0287] It has been demonstrated here that in the absence of any natural light, on young tomato plants, 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%.

[0288] With the use of a 100% red spectrum over part of the photoperiod:

[0289] - a maintenance of agronomic efficiency and therefore of development was observed while reducing electricity consumption if the amount of PAR supplied during the phases is equivalent to the control (i.e., during treatment 1),

[0290] - an increase in plant development was observed, resulting in through better biomass production and an advanced stage of development if the amount of PAR supplied is increased. Example of a young cucumber plant: Materials and methods

[0291] This experiment was carried out with young cucumber plants in an indoor growing room at PARC (Photobiologic and Agronomy Research Center). This The experiment began on May 2, 2024 and ended on May 29, 2024. Three light treatments were compared. Plant material and growing conditions

[0292] 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 plants were transplanted into Grodan rockwool cubes. There were two plants per cube, and the density was 19 plants / m². Light treatments were applied on May 4, 2024.

[0293] For this trial, 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.

[0294] The climate in the growth chambers was controlled by a Hoogendoom horticultural climate computer. The conditions were as follows:

[0295] - Day / night temperature: 23 / 22 °C during the first half of the growth cycle, then 22 / 20 °C

[0296] - Relative humidity: 60-80%

[0297] - CO2: 500 ppm Light treatments

[0298] The lighting used is the REDT 680 developed by RED Horticulture. This lighting 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.

[0299] The wavelengths of the colors blue, green, red and far-red have been defined as follows:

[0300] - Blue: 400-500 nm

[0301] - Green: 500-600 nm

[0302] - Red: 600-700 nm

[0303] - Far red: 700-800 nm

[0304] To verify the spectral qualities, a PG200N spectroradiometer from UPRtek was used. Characteristics of light treatments

[0305] - Photoperiod: 16h

[0306] - Luminous intensity: 140 pmol.m².s⁻¹

[0307] - DLI (Daily light integral): 8 mol.m 2.s 1

[0308] - Spectral quality (B means blue, G means green, R means red and FR means far red, different phases are separated by the symbol « » ; the numbers indicate a distribution of light intensity):

[0309] • Treatment 1: 18B / 18G / 57R / 7FR 16h

[0310] • Treatment 2: 18B / 18G / 57R / 7FR 6h 100R 8h 18B / 18G / 57R / 7FR 2h

[0311] • Treatment 3: 18B / 18G / 57R / 7FR 6h 100R 8h 18B / 18G / 57R / 7FR 2h (20% increase in luminous intensity for phase 100R so that the luminous intensity is 168 pmol.m 2.s ')

[0312] For example, "18B / 18G / 57R / 7FR 16h" designates 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. Plant analysis Morphological measurements

[0313] - Sample: 8 plants per variety and per treatment

[0314] - Duration: 4 weeks of measurement Plant monitoring

[0315] Frequency:

[0316] - First week: 1 time, 7 days after lighting

[0317] - Weeks 2, 3 and 4: 2 times per week, full monitoring - daily for height of the plant and the number of leaves Total height (cm)

[0318] Measure using a ruler from the base of the rock wool cube to the top of the plant. Number of sheets

[0319] Count the number of fully unfurled leaves after the cotyledons. By "fully unfurled" is meant flat leaves longer than 1.5 cm

[0320] Fresh weight: fresh mass of the plant / leaf / stem (g)

[0321] - Mass of the plant cut at the collar, measured on a precision balance.

[0322] - Mass of the plant's leaves (including the petiole), measured on a balance of precision.

[0323] - Mass of the plant stem, measured on a precision balance. Statistical analysis

[0324] Statistical analyses are performed on the data obtained for all plants in each replicate and for each of the measured criteria. They are processed using R software. The data are processed with a one-way analysis of variance (ANOVA, p < 0.05) (light processing). If significant differences between the variances studied are found, the means are then compared pairwise using a Tukey test (Honest Significant Difference, HSD, p < 0.05). When the residuals do not meet the conditions of normality and homoscedasticity, the Kruskal-Wallis test is performed, followed by a Wilcoxon Mann-Whitney test (p < 0.05). Results

[0325] Effects of different light treatments on the growth and fresh weight of the young cucumber plant

[0326] 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.

[0327] Plant height was significantly impacted by light treatment. A variety-dependent effect was observed. 27 days after sowing, for the Dunavine variety, plants in treatment 1 were significantly taller by 11.3% and 14.3% 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 by 10.4% than plants in treatment 3.

[0328] Figures 6c and 6d show the impact of the light spectrum emitted by LED lighting on the leaf growth of young cucumber plants, respectively of 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.

[0329] As with height, a variety-dependent effect is observed for the number of leaves. Plants of the Dunavine variety have significantly 11% 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.

[0330] Figures 6e and 6f show the impact of the light spectrum emitted by LED lighting on the fresh weight of cucumber seedlings, respectively of 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.

[0331] No significant varietal effect was observed for the fresh weight of the young cucumber plants. For both varieties, plants in treatment 3 had a higher fresh weight compared to plants in treatments 1 and 2, which showed 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. Discussion

[0332] For the young cucumber plant, depending on the producers and environmental conditions, some will want to compact the young plants and others will want to lengthen them.

[0333] A reduction in electricity consumption without altering agronomic performance thanks to the red alternating spectrum

[0334] 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.

[0335] An increase in agronomic performance with increasing light intensity of red monochromatic

[0336] Treatment 3 (which corresponds to treatment 2 with a 20% increase in light intensity during the 8 hours of 100% red light) provides, over the total photoperiod, an additional 10% of artificial light in terms of light intensity (particularly 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 increases agronomic performance by reducing the development cycle and also by improving biomass accumulation, resulting in better plant development.

[0337] Treatment 3 has the same electrical consumption as treatment 1 but significantly increased agronomic performance. Conclusion

[0338] 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 660 nm 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 light source. polychromatic comprising at least one other wavelength in a proportion between 10 and 100%.

[0339] With the use of a 100% red spectrum over part of the photoperiod:

[0340] - a maintenance of agronomic efficiency and therefore of development has been observed while reducing electricity consumption if the amount of PAR supplied during the phases is equivalent to the control (i.e., during treatment 1),

[0341] - an increase in plant development was observed, resulting in through better biomass production and an advanced stage of development if the amount of PAR supplied is increased. Example of a young pepper plant: Materials and methods

[0342] This experiment was carried out with young pepper plants in an indoor growing room at PARC (Photobiologic and Agronomy Research Center). This experiment began on August 1, 2024 and ended on September 18, 2024. Three light treatments were compared. Plant material and growing conditions

[0343] Pepper seeds of two varieties, Alzamora (Rijk Zwaan) and Levente (Enza Zaden), were sown in Grodan rockwool plugs and then covered with perlite. After 2 weeks, the plants were transplanted into Grodan rockwool cubes. There was one plant per cube, and the density was initially 100 plants / m², decreasing to 22 plants / m² after spacing. Light treatments were applied on August 6, 2024.

[0344] For this test, 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.

[0345] The climate in the growth chambers was controlled by a Hoogendoom horticultural climate computer. The conditions were as follows:

[0346] - Day / night temperature: 23 / 21 °C for the first 3 weeks, then 21.5 / 19.5 °C.

[0347] - Relative humidity: 60-80%.

[0348] - CO2: 500 ppm Light treatments

[0349] The lighting used is the REDT 680 developed by RED Horticulture. This lighting allows control of 4 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, we used a PG200N spectroradiometer from UPRtek.

[0356] Characteristics of light treatments - Photoperiod: 14h

[0357] - Luminous intensity: 140 pmol.m².s¹

[0358] - DLI (Daily light integral): 7 mol.m 2.s 1

[0359] - Spectral quality (B means blue, G means green, R means red and FR means far red, different phases are separated by the symbol « »; the numbers indicate a distribution of light intensity):

[0360] • Treatment 1: 15B / 15G / 63R / 7FR 14h

[0361] • Treatment 2: 15B / 15G / 63R / 7FR 5h 100R 7h 15B / 15G / 63R / 7FR 2h

[0362] • Treatment 3: 15B / 15G / 63R / 7FR 5h 100R 7h 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 *) Plant analysis Morphological measurements

[0363] - Sample: 8 plants per variety and per treatment

[0364] - Duration: 4 weeks of measurements Plant monitoring

[0365] Frequency:

[0366] - First week: 1 time, 7 days after lighting

[0367] - Weeks 2, 3 and 4: 2 times per week, full monitoring - daily for height of the plant and the number of leaves. Total height (cm)

[0368] Measure using a ruler from the base of the rock wool cube to the top of the plant. Number of sheets

[0369] Count the number of fully unfurled leaves after the cotyledons. By "fully unfurled" is meant flat leaves longer than 1.5 cm.

[0370] Fresh weight: fresh mass of the plant / leaf / stem (g)

[0371] - Mass of the plant cut at the collar, measured on a precision balance.

[0372] - Mass of the plant's leaves (including the petiole), measured on a balance of precision.

[0373] - Mass of the plant stem, measured on a precision balance. Statistical analysis

[0374] 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 R software. The data were analyzed using 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). Results

[0375] Effects of different light treatments on the growth and fresh weight of the young pepper plant

[0376] Figures 7a and 7b show the impact of the light spectrum emitted by LED lighting on the height of young pepper plants, respectively of the Levente and Alazamora varieties, measured at 20, 27, 29, 34, 41, and 48 days after sowing. Significance is indicated by letters following a Tukey 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.

[0377] 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 smaller 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.

[0378] Figures 7c and 7d show the impact of the light spectrum emitted by LED lighting on the leaf growth of young pepper plants, respectively of 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 as a function of time, expressed as the number of leaves.

[0379] Plants of the Levente variety had significantly more leaves in treatment 3 compared to treatments 1 and 2. For Alzamora, plants in treatment 3 had 10.2% and 16.5% more leaves than plants in treatment 1 and 2 respectively. Treatments 1 and 2 show no significant difference for the two varieties.

[0380] Figures 7e and 7f show the impact of the light spectrum emitted by LED lighting on the total fresh weight of young pepper plants, respectively of the Levente and Alazamora varieties, and its distribution measured 48 days after sowing. Significance is indicated by letters following a Tukey 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.

[0381] Plants from treatments 1 and 2 show no significant difference in total fresh weight for the two varieties. For Alzamora, treatment 3 results in an increase in total weight of 9.7% and 13.8% compared to treatments 1 and 2. For Levente, treatment 3 only results in an increase in total fresh weight of 9.5% compared to treatment 2. Discussion

[0382] For young pepper plants, producers will most often want to compact the young plants. This is what treatment 3 allows here.

[0383] A reduction in electricity consumption without altering agronomic performance thanks to the red alternating spectrum

[0384] 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.

[0385] An increase in agronomic performance with increasing light intensity of red monochromatic

[0386] 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 (particularly 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 development cycle and also by increasing biomass accumulation, resulting in better plant development.

[0387] Treatment 3 has the same electrical consumption as treatment 1 but significantly increased agronomic performance. Conclusion

[0388] It has been demonstrated here that, in the absence of any natural light, on young pepper plants, it is possible to use artificial lighting whose spectrum is monochromatic red 660nm, 50% of the total photoperiod duration, totally 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%.

[0389] With the use of a 100% red spectrum over part of the photoperiod:

[0390] - a maintenance of agronomic efficiency and therefore of development has been observed while reducing electricity consumption if the amount of PAR supplied during the phases is equivalent to the control (i.e., during treatment 1),

[0391] - an increase in plant development was observed, resulting in through better biomass production and an advanced stage of development if the amount of PAR supplied is increased.

Claims

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 radiation is artificially emitted, the secondary radiation 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 red phase represents less than 90% of the photoperiod.

3. A method according to any one of claims 1 and 2, 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.

4. A method according to any one of claims 1 to 3, wherein the secondary radiation includes blue radiation, green radiation, red radiation and far-red radiation.

5. A method according to claim 4, 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, 40 to 95% of the total luminous intensity of the secondary radiation corresponds to red radiation and 1 to 20% of the total luminous intensity of the secondary radiation corresponds to far-red radiation.

6. A method according to any one of claims 1 to 5, wherein red radiation is radiation with a wavelength between 600 and 700 nm.

7. A method according to any one of claims 1 to 6, 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.

8. A method according to any one of claims 1 to 7, wherein a luminous intensity of the primary radiation is greater than or equal to a total luminous intensity of all the secondary radiation(s).

9. A method according to claim 8, wherein the luminous intensity of the primary radiation is at least 10% greater than the total luminous intensity of all the secondary radiation(s).

10. A method according to any one of claims 1 to 9, wherein the emission step comprises a first multispectral phase implemented before the red phase and a second multispectral phase implemented after the red phase.

11. A method according to any one of claims 1 to 10, 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.

12. Device (1) for artificially lighting a plant 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 11.

13. Device according to claim 12, 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 the duration of one or each of the phases depending on parameters relating to plant development and / or parameters relating to the plant environment.

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