Lighting system and method

Abstract

The present disclosure relates to a horticultural lighting method to illuminate cannabis seedlings or cuttings during a propagation phase of young plants. The method comprises: lighting the seedlings or cuttings with red light and auxiliary lighting with far red light during an initial rooting period in the propagation phase of at least four days up to eleven days. An intensity level of the lighting with red light is below a threshold, at or above which threshold photosynthesis is dominant. An intensity level of auxiliary lighting with far red light is between one and up to (and beyond) 10 times the intensity level of lighting with red light. The disclosure also relates to a corresponding system to embody the method.

Description

[0001] Lighting system and method

[0002] FIELD OF THE INVENTION

[0003] The present disclosure relates to the field of lighting systems and associated or corresponding methods for the cultivation of specific types of plants, amongst which cannabis.

[0004] BACKGROUND OF THE INVENTION

[0005] For example, plants of the genus Cannabis (“cannabis”) are flowering annual plants, which includes at least the species Cannabis sativa. Cannabis indica and Cannabis ruderalis are either seen as sub-species / varieties of Cannabis sativa, or as separate species (under the genus Cannabis) in their own right.

[0006] Cannabis flowers produce valuable phytochemicals as a by-product, such as terpenes and cannabinoids (such as THC and CBD). It is known to use several of these phytochemicals to relieve the symptoms of a number of medical conditions, such as relieving pain and / or preventing nausea. There is a worldwide interest in the medical use of cannabis, and an increasing trend towards legalizing the medical use of cannabis.

[0007] It is usually considered necessary to grow cannabis under controlled circumstances to be able to guarantee a sufficient quality for medicinal purposes. For this reason, growth mostly takes place in greenhouses or indoor (i.e. without daylight). For improved and repeatable quality, e.g. improved and reproducible phytochemical content, supplemental light (e.g. provided by an LED arrangement) is often used.

[0008] A typical growth cycle of a cannabis plant in a commercial greenhouse or indoor setting consists of several distinguishable growth phases. Plants begin in the propagation phase, in which young plants are propagated from seedlings and / or cuttings. Plants then move to the vegetative phase, in which the female plants are transplanted to a lower plant density and grown to a certain degree of maturity. This is called the vegetative phase. After the vegetative phase, there is a flowering phase that start with a transition to the reproductive phase (i.e. flowering). Cannabis plants are so-called short-day plants. They start flowering when the photoperiod is shortened. To induce flowering, the photoperiod is shortened to typically 12 hours per day. At the end of the flowering phase, the flowers are harvested.

[0009] Medical cannabis cultivation is nowadays mostly performed in indoor environments, especially in totally controlled environment under artificial lighting. Light intensities during the flowering phase of cultivation are as high as 1000 pmol / m2 / s or even 1500 pmol / m2 / s.

[0010] For the production of large numbers of uniform and genetically identical plants at low cost, rooting of stem cuttings is often used in commercial cultivation. However, for some unknown reason, some cannabis species have a hard time producing roots. Many cannabis growers grow many different cannabis species and also are themselves breeders. No one grower / breeder has the same species on the market and thousands of type of cannabis are cultivated. Further, new species are created very regularly. Many cannabis species are very interesting for compounds but are - at the same time - not easy to root. Rooting success beneath 80% isn’t interesting for a commercial growth. Besides, when rooting success is low (beneath 98 %) it can also affect the further development of the plant and slow rooting cuttings have shown a tendency to result in smaller plants with less yields and sometimes less potency (being shorter they would receive less light and be more in the shade).

[0011] External application of synthetic auxin hormones is in some cases forbidden for growing medicinal products, such as cannabis. As a consequence, rooting may take much longer than when using synthetic auxin. Auxins are powerful growth hormones produced naturally by plants, found in shoot and root tips, which promote cell division, stem and root growth. Synthetic auxins are artificially manufactured versions, that are sometimes used in agriculture to promote plant growth. Indole-3 -acetic acid (IAA) is the most abundantly available natural auxin, produced in the shoot apical meristem or young leaves and is then then polarly transported to the base by a cell-to-cell transport or through phloem. This molecules composes most of the artificial auxin powder or gel on the market. Most of the time, a concentration of 0.3 % is sufficient and works with most plants species.

[0012] As an alternative for application of (synthetic) auxin, it is possible (and also in medicinal agriculture: allowed) to use lighting in order to use endogenous auxin to induce adventitious rooting. Light is one of the environmental factors that can be controlled easily to monitor and steer plant development. By using appropriate lighting, it’s possible to promote movement of naturally present auxin into the shoot and transported the auxin into the root zone, where such natural auxins trigger adventitious rooting. This auxin transport is accompanied with an elongation of the stem which also clearly indicates the rooting success. For a grower it is important to know when a cutting is rooted and if all the cuttings are synchronized in their rooting success to guarantee a good uniformity of vegetative / flower development in the following vegetative and flowering growth stages. Cuttings that are rooting with delay can be set aside to grow under a different light regime (e.g. be exposed for a longer time to a lighting recipe designed to keep the plants in vegetative phase, before inducing he flowering phase) in order to catch up with their growth or to be forming a different group that will be dedicated for extraction rather than flower sales.

[0013] Excessive elongation of the stem should be avoided, since stem elongation occurs at the expense of a speed of rooting. Therefore, skilled person in this field have sought for an improved lighting recipe to be employed in the propagation phase, to obtain more uniformity and higher propagation success rates, also in the subsequent vegetative and flowering phases.

[0014] SUMMARY OF THE INVENTION

[0015] Methods and systems according to the present disclosure provides a number of improvements over the prior art.

[0016] The creators of the present disclosure have, after diligent and confidential research, been able to identify an improvement in a horticultural lighting method and system configured to cultivate plants. According to the present disclosure, a low red:far red ratio helps activate endogenous auxin and promote rooting. However, rooting is impeded if the red:far red ratio is too low or if the red intensity is too high. Furthermore, excessive stem elongation occurs if far red lighting is maintained for too long. Consequently, far red lighting should be switched off after an appropriate time period. Surprisingly, the creators have found that replacing far red lighting with blue lighting in a non-limiting preferred embodiment will reduce excessive stem elongation.

[0017] Thus, the present disclosure relates to a horticultural lighting method to illuminate cannabis seedlings or cuttings during a propagation phase of young plants, comprising: lighting the seedlings or cuttings with red light and auxiliary lighting with far red light, during an initial rooting period in the propagation phase of at least four days up to eleven days with:

[0018] - an intensity level of the lighting with red light below a threshold, at or above which threshold photosynthesis is dominant; and - an intensity level of the auxiliary lighting with far red light between one and up to (or even beyond) 10 times the intensity level of the lighting with red light.

[0019] In a possible embodiment, the method exhibits the feature that the initial rooting period is between five and ten days.

[0020] In an alternative or additional embodiment, the method exhibits the features that, in the initial rooting period, the threshold of the lighting is at 50 pmol / m2 / s, the intensity level of lighting with red light is between 30 and 50 pmol / m2 / s and the intensity level of auxiliary lighting with far red light is between 40 and 100 pmol / m2 / s.

[0021] In an alternative or additional embodiment, the method exhibits the features of, in the initial rooting period, monitoring at least one of root development and cutting stem elongation, and terminating auxiliary lighting with far red light, when a desired root development or stem elongation has been reached. Further, the method may exhibit the feature that the monitoring comprises deployment of a camera and estimating root development or stem elongation from captured images. Additionally or alternatively, the method may comprise at least once within the initial rooting period, identifying longest or most elongated stems and transferring the longest or most elongated stems from lighting with the red light and the auxiliary lighting with the far red light. Additionally or alternatively the method may further comprise terminating auxiliary lighting with far red light at a stem elongation of 20%.

[0022] In an alternative or additional embodiment, the method exhibits the features that, after the initial rooting period of lighting the seedlings or cuttings with red light and auxiliary lighting with far red light, in a subsequent period of at least four days up to twelve days of the propagation phase: lighting the seeds or cuttings with red light and complementary lighting with blue light, wherein complementary lighting with blue light replaces auxiliary lighting with far red light of the initial rooting period, and wherein complementary lighting with blue light in the subsequent period is provided in a same intensity level as auxiliary lighting with far red light in the initial rooting period. Then, the method may further comprise the feature that, in the subsequent period, the total intensity level of lighting with at least red light and complementary lighting with blue light is between 100 and at least 150 pmol / m2 / s. Additionally or alternatively, the method may comprise the feature that the complementary lighting with blue light in the subsequent period has an intensity of at least 20% of the combined lighting and complementary lighting. In an alternative or additional embodiment, the method exhibits the features that, in the initial rooting period, the seeds or cuttings are maintained at about 27°C. Then variations relative to this feature could be limited to within + / - 1°C.

[0023] In an alternative or additional embodiment, the method exhibits the features that, in the initial rooting period, the seeds or cuttings are maintained at a humidity between 80 and 90%.

[0024] In an alternative or additional embodiment, the method exhibits the features that, in the initial rooting period, the seeds or cuttings are placed on a wet substrate, selected from a group comprising stone and glass wool.

[0025] In an alternative or additional embodiment, the method exhibits the features of, in the initial rooting period, refraining from irrigation during at least approximately five days from the beginning of the initial rooting period.

[0026] In an alternative or additional embodiment, the method exhibits the features that, in the initial rooting period, a photoperiod per day is either between 16 and 18 hours or 24 hours.

[0027] In an alternative or additional embodiment, the method exhibits the features that the red light has a wavelength in a range between 600 and 699 nm and far red light has a wavelength in a range between 700 and 799 nm.

[0028] Further the present disclosure relates to a horticultural lighting system configured to illuminate cannabis seedlings or cuttings during a propagation phase of young plants, with the system comprising:

[0029] - an irradiation system for irradiating seedlings and / or cuttings; and

[0030] - a data processing system in controlling communication with the irradiation system and comprising at least one processor, wherein the processor is configured to control the irradiation system to: illuminate the seeds or cuttings by lighting with red light and auxiliary lighting with far red light during an initial rooting period in the propagation phase of at least four days up to eleven days with an intensity level of lighting with red light below a threshold, at or above which threshold photosynthesis is dominant, and an intensity level of auxiliary lighting with far red light between one and up to (or even beyond) 10 times the intensity level of red.

[0031] Thus, a system as described above and hereinafter may be controlled using the method of the present disclosure. The method may be executed, for example, by the data processing system described above and hereinafter. Moreover, a computer program for carrying out the methods described herein, as well as a non-transitory computer readable storage-medium storing the computer program are provided. A computer program may, for example, be downloaded by or uploaded to an existing device or be stored upon manufacturing of these systems.

[0032] A non-transitory computer-readable storage medium stores at least one software code portion, the software code portion, when executed or processed by a computer, being configured to perform executable operations comprising: obtaining a target light level, determining a first set of light settings for a set of one or more lights and / or a first set of daylight blocker settings for a set of one or more daylight blockers based on said target light level, controlling said set of lights based on said first set of light settings and / or said set of daylight blockers based on said first set of daylight blocker settings, receiving from a user device information indicating a quality of a data signal received by said user device from one or more lights of said set of lights, said data signal being transmitted by modulating a light signal and said signal quality being determined by said user device, determining a second set of light settings for said set of lights based on said first set of light settings and said determined signal quality and / or a second set of daylight blocker settings for said set of daylight blockers based on said first set of daylight blocker settings and said determined signal quality, and controlling said set of lights based on said second set of light settings and / or said set of daylight blockers based on said second set of daylight blocker settings.

[0033] As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as a device, a method or a computer program product. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a "circuit", "module" or "system." Functions described in this disclosure may be implemented as an algorithm executed by a processor / microprocessor of a computer. Furthermore, aspects of the present invention may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied, e.g., stored, thereon.

[0034] Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of a computer readable storage medium may include, but are not limited to, the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of the present invention, a computer readable storage medium may be any tangible medium that can contain, or store, a program for use by or in connection with an instruction execution system, apparatus, or device.

[0035] A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

[0036] Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fibre, cable, RF, etc., or any suitable combination of the foregoing. Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java(TM), Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer, or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0037] Aspects of the present invention are described below with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor, in particular a microprocessor or a central processing unit (CPU), of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer, other programmable data processing apparatus, or other devices create means for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0038] These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function / act specified in the flowchart and / or block diagram block or blocks.

[0039] The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0040] The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of devices, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and / or flowchart illustrations, and combinations of blocks in the block diagrams and / or flowchart illustrations, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions. BRIEF DESCRIPTION OF THE DRAWING

[0041] In the appended drawing, embodiments of the present disclosure and components thereof are shown, wherein the same or similar elements, components and functional aspects may be designated throughout the drawing with the same or similar reference signs and wherein:

[0042] FIG. 1 schematically illustrates a system for irradiating seedlings or cuttings during a seedling propagation phase;

[0043] FIG. 2 illustrates an exemplary data processing system having at least a processor to control the horticultural lighting system and perform the method in accordance with the present disclosure;

[0044] FIG. 3 exhibits a lighting recipe according to the present disclosure; and FIG’s. 4 and 5 exhibit graphs of the effects attainable by the present disclosure.

[0045] DETAILED DESCRIPTION OF EMBODIMENTS

[0046] In the figures, the same or similar reference numbers indicate identical or similar elements, components or functional units.

[0047] In Fig. 1, an exemplary system 1 for irradiating seedlings or cuttings 11 is shown, for example in a green house. However, the present disclosure may equally well be deployed in a vertical farm setting, which may be closed off and receive no daylight. System 1 comprises an irradiation system 3 with light sources 5, for example LED light sources, which are connected to a hub 7.

[0048] Hub 7 is connected to a data processing system 100 of FIG. 2 comprising at least one processor 102. Processor 102 is able to acquire information on a desired lighting recipe from a source 9. Alternatively, the recipe may be stored in a memory of the data processing system 100. A network, such as the internet, may be present between the source 9 and processor 102, or between the processor 102 and the irradiation system 3. Further, system 1 may comprise a camera 13 to monitor shoot elongation and / or root growth, and data processing system 100 may be provided with the monitoring information to determine a duration of an initial rooting period between 4 and eleven days, or more often between five and ten days, at which shoot elongation may have a value of for example 20%.

[0049] Lamps 5 of the irradiation system 3 are configured to generate at least red light having a wavelength of 600-699 nm and far-red light with a wavelength of 700-799 nm. In a specific embodiment, lamps 5 of the irradiation system 3 may need to be capable of generating blue light with a wavelength of 400 - 499 nm, as will be discussed in more detail herein below. Different lamps 5 may be used for generating distinct regions of the spectrum. However, in articular when using LED light lamps, these may be controllable to generate more than one of the mentioned (or other) regions of the EM radiation.

[0050] It is noted here that considerable portions of the region of EM radiation referred to herein as far-red light are not visible to the human eye. Far-red (FR) light at the extreme end of the visible light spectrum (700 - 799 nm) is only dimly visible to a human eye. Further, far-red light was considered in the past not to contribute to photosynthesis, or hardly so. A reason for this is that photosynthetic efficiency of monochromatic far-red light is poor and is for the most part reflected and / or transmitted, where as little as approximately 30% of monochromatic far-red light is absorbed by plant leaves. As a consequence, even nowadays far-red light is not included in the definition of PAR (‘Photosynthetically Active Radiation’ with wavelengths in the range of 400 - 700 nm). However, photons of far-red light have been proven to exhibit interaction with photons of shorter wavelength light in the visible region of EM radiation or the PAR, resulting in a considerable improvement of the achievable photosynthesis efficiency. The present disclosure is based on this insight.

[0051] Fig. 2 depicts a block diagram illustrating an exemplary data processing system 100, that may be at the heart of the system and / or perform the method as described herein reference.

[0052] As shown in Fig. 2, the data processing system 100 may include at least one processor 102 coupled to memory elements 104 through a system bus 106. As such, the data processing system may store program code within memory elements 104. Further, the processor 102 may execute the program code accessed from the memory elements 104 via a system bus 106. In one aspect, the data processing system may be implemented as a computer that is suitable for storing and / or executing program code. It should be appreciated, however, that the data processing system 100 may be implemented in the form of any system including a processor and a memory that is capable of performing the functions described within this specification.

[0053] The memory elements 104 may include one or more physical memory devices such as, for example, local memory 108 and one or more bulk storage devices 110. The local memory may refer to random access memory or other non-persistent memory device(s) generally used during actual execution of the program code. A bulk storage device may be implemented as a hard drive or other persistent data storage device. The processing system 100 may also include one or more cache memories (not shown) that provide temporary storage of at least some program code in order to reduce the quantity of times program code must be retrieved from the bulk storage device 110 during execution. The processing system 100 may also be able to use memory elements of another processing system, e.g. if the processing system 100 is part of a cloud-computing platform.

[0054] Input / output (I / O) devices depicted as an input device 112 and an output device 114 optionally can be coupled to the data processing system. Examples of input devices may include, but are not limited to, a keyboard, a pointing device such as a mouse, a microphone (e.g. for voice and / or speech recognition), or the like. Examples of output devices may include, but are not limited to, a monitor or a display, speakers, or the like. Input and / or output devices may be coupled to the data processing system either directly or through intervening I / O controllers.

[0055] In an embodiment, the input and the output devices may be implemented as a combined input / output device (illustrated in Fig. 2 with a dashed line surrounding the input device 112 and the output device 114). An example of such a combined device is a touch sensitive display, also sometimes referred to as a “touch screen display” or simply “touch screen”. In such an embodiment, input to the device may be provided by a movement of a physical object, such as e.g. a stylus or a finger of a user, on or near the touch screen display.

[0056] A network adapter 116 may also be coupled to the data processing system to enable it to become coupled to other systems, computer systems, remote network devices, and / or remote storage devices through intervening private or public networks. The network adapter may comprise a data receiver for receiving data that is transmitted by said systems, devices and / or networks to the data processing system 100, and a data transmitter for transmitting data from the data processing system 100 to said systems, devices and / or networks. Modems, cable modems, and Ethernet cards are examples of different types of network adapter that may be used with the data processing system 100.

[0057] As pictured in Fig. 2, the memory elements 104 may store an application 118. In various embodiments, the application 118 may be stored in the local memory 108, the one or more bulk storage devices 110, or separate from the local memory and the bulk storage devices. It should be appreciated that the data processing system 100 may further execute an operating system (not shown in Fig. 2) that can facilitate execution of the application 118. The application 118, being implemented in the form of executable program code, can be executed by the data processing system 100, e.g., by the processor 102. Responsive to executing the application, the data processing system 100 may be configured to perform one or more operations or method steps described herein. FIG. 3 exhibits a light recipe according to the present disclosure, which is executed by irradiation system 3 under control of the data processing system 100.

[0058] Seedlings or cuttings 11 are initially - in an initial rooting period - illuminated with at least red light and far-red light. Illumination using other colors is optional, and possible within the scope of the present disclosure. Far-red light is illuminated in a range of intensities from at least approximately equal to the intensity of red light up to twice that intensity, or potentially even more. More in detail, if red light is illuminated at an intensity of 30 - 50 pmol / m2 / s (not considering optionally also generated blue, green, PAR or white light) the far-red light may be generated in an intensity of 40 - 100 pmol / m2 / s, or more.

[0059] Limitation of the illumination during the initial rooting period in the visible or PAR range of 400 - 700 nm to a maximum of 50 pmol / m2 / s or less corresponds with a value at which photosynthesis is not dominating, i.e. at a limit of negative photosynthetic rate, which is in the range of the compensation point of respiration and photosynthesis.

[0060] The recipe in FIG. 3 and according to the present disclosure was extensive and confidentially tested at university and in two commercial grower production lines. Without a light recipe and without applying (artificial) auxins, the rooting percentage was below 70% in practically all cases. Also, rooting of plant seedling takes on average more time (several days to weeks) than when applying (artificial) auxin. Tests were also done under a combined auxin application and light recipe to check weather rooting uniformity can still be improved.

[0061] A total of 40 rootings per treatment were tested 4 times, and a total of 5 cultivars were tested. The best rooting scores and uniformity in rooting in FIG’s. 4 and 5 were obtained by applying a Red:Far-Red ratio of 1 or 0.5 with a light level of red light between 30 and 50 pmol / m2 / s and a far red level of 40 to 50 or from 80 to 100 pmol / m2 / s or from 40 to 100 pmol / m2 / s depending on the desired ratio. The ratio of choice is cultivar dependent and is depending on how fast a grower wants to accelerate rooting. With a lower Red:Far-Red ratio, shoot elongation will be higher and this could be compensated in a following phase.

[0062] The initial rooting period lasts from four up to eleven days, but more often between five and ten days depending on the cultivar and the amount of elongation to be realized before ending the initial rooting period by terminating lighting with far-red light. A low Red:Far-Red ratio thus helps rooting. It has also been found that if the Red:Far-red ratio is too low it can be counter-productive (comparable with application (if it were allowed) of too much auxin), or if the Red intensity is too high as well. Elongation is achieved more quickly using the light recipe (and without auxin), and the Far-Red light is turned off when a desired degree of elongation has been realized. As mentioned above, this may take five to ten days, which is considerable faster than when using no auxin and no light recipe, and the success rate is moreover considerably increased. A desired elongation of for example 20% may need to be realized, at which time the Far-Red light may be turned off. This may be monitored using camera 13 in FIG. 1 for control over illumination system 3 by data processing system 100. Thus, growers are provide with the means to apply different doses of Far-Red to accommodate the sensitivity and the needs of his particular cultivar for auxin transport. Rooting success is detectable (using camera 13) from the shoot elongation and after few cm of shoot elongation and without the observable appearance of roots outside the substrate, it may be assumed that the rooting process is engaged. Then, after a desired shoot elongation is detected, of for example 20%, Far-Red can be turned off and optionally replaced (see below) by high blue ratio to allow the seedling to remain compact in its further development.

[0063] At least during the initial rooting period, cuttings should be maintained at about 27 deg C, where deviation of + / - 1 deg C or a bit more or less may be tolerated, and at a 80 to 90 % humidity. Good results are obtained with a wet stone- or rockwool block as substrate, but glass wool may be used as well. In the first five days, no irrigation should be applied.

[0064] The side camera 13 can monitor the elongation process of the cuttings and after cuttings have started elongating, the processor 102 may turn off the Far-Red light accordingly and optionally apply the blue light instead.

[0065] At day four or five into the initial rooting period, processor 102 may make a selection of the longest or most elongated shoots and they can be sorted out to be brought under a high blue light zone while other cuttings continue to receive Far-Red light treatment. The present disclosure may be equally applicable to Cannabis seed germination.

[0066] A longer photoperiod per day of Red:Far-Red illumination may enhance the dose of Far-Red. Then, a longer photoperiod of e.g. 18 or 24h instead of e.g. 12, 14 or 16h can be set. However, adding too much Far-Red light will not be efficient as an over-stimulus of far red will have the opposite effect and rooting success will decrease. In the same way, when adding too high concentration of auxin with a chemical, decrease rooting will ensue. This is quite comparable with applying to much (artificial) auxin.

[0067] Optionally, in a period following the initial rooting period of five to ten days, the Far-Red light may be replaced by Blue light in the same intensity as the Far-Red light in the preceding initial rooting period, i.e. in an intensity of 40 - 100 pmol / m2 / s to counteract (excessive) elongation, and promote root growth. In this subsequent period, total illumination intensity of Blue and Red (and optionally also other colors) is preferably limited to 100 - 150 pmol / m2 / s. For this reason, the block in FIG.3 for Red light is left empty and no intensity value or range is mentioned therein, since the intensity of red will follow from the amount of Blue light in relation green, white and blue light or other light generated, and the interrelationship there between, comparison with Blue light illumination preferably constitutes about 20% or more of the total amount / intensity of light generated in the subsequent period after the initial rooting period, which is indicated above as constituting ‘high blue ratio’. Blue light illumination may be maintained during the subsequent period, which may last between four and twelve days, to conclude the propagation phase after at the latest 21 days, after which the vegetation phase may be begun, for which the young plants may need to be transferred to another growth medium. However, blue light may be turned off before the end of the propagation phase and / or a start of the vegetation phase (indicated by a dashed line in the block for blue light after the initial rooting period in the subsequent period), if the above desired effect is achieved.

[0068] In FIG’s. 4 and 5, comparative results are shown for in each case two cultivars ‘ 1’ and ‘2’. The top graphs in FIG’s. 4 and 5 show root scoring, which is a measure to assess the size and amount of developed roots. To arrive at root scoring graphs in FIG’. 4 and 5, it’s possible to use a scoring chart that is pre-calibrated for each species of plant. In the case of the present disclosure, a scoring chart especially for cannabis has been developed. The rooting score graphs in FIG’s. 4 and 5 exhibit effects of the present disclosure relative to such previous rooting charts, that therefore function as a reference or control to verify efficacy of the proposed method and system.

[0069] Letters A-D in upper and lower case categorize that statistical analysis is showing a resp. more or less significant difference.

[0070] The equal sign means that compare to control a same length is realized compared to the previous control (so no elongation) and an arrow in a bar of the graphs indicates an increase compared to control (which could be considered redundant, because the categorization with letters A-D in fact also indicates the same.

[0071] In FIG. 5 reference is made to ‘dynamic’, which is used to indicate that in the total duration of the rooting phase the light spectrum is dynamically changed or varied. If only intensity is changing, this would be referred to as dimming, but the tests indicated with ‘dynamic’ involved varying the spectrum. In the bottom graphs, FIG’s. 4 and 5 show heights of plants. When a desired height is achieved, Far-Red may be turned off. Instead, after the initial rooting period, in a subsequent period, a same or similar dose off Blue may thereafter be administered, instead of the far red dose in the initial rooting period.

[0072] Various embodiments of the invention may be implemented as a program product for use with a computer system, where the program(s) of the program product define functions of the embodiments (including the methods described herein). In one embodiment, the program(s) can be contained on a variety of non-transitory computer-readable storage media, where, as used herein, the expression “non-transitory computer readable storage media” comprises all computer-readable media, with the sole exception being a transitory, propagating signal. In another embodiment, the program(s) can be contained on a variety of transitory computer-readable storage media. Illustrative computer-readable storage media include, but are not limited to: (i) non-writable storage media (e.g., read-only memory devices within a computer such as CD-ROM disks readable by a CD-ROM drive, ROM chips or any type of solid-state non-volatile semiconductor memory) on which information is permanently stored; and (ii) writable storage media (e.g., flash memory, floppy disks within a diskette drive or hard-disk drive or any type of solid-state random-access semiconductor memory) on which alterable information is stored. The computer program may be run on the processor 302 described herein.

[0073] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0074] The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of embodiments of the present invention has been presented for purposes of illustration, but is not intended to be exhaustive or limited to the implementations in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the present invention. The embodiments were chosen and described in order to best explain the principles and some practical applications of the present invention, and to enable others of ordinary skill in the art to understand the present invention for various embodiments with various modifications as are suited to the particular use contemplated.

Claims

CLAIMS1. A horticultural lighting method to illuminate cannabis seedlings or cuttings during a propagation phase of young plants, comprising: lighting the seedlings or cuttings with red light and auxiliary lighting with far red light, during an initial rooting period in the propagation phase of at least four days up to eleven days with:- an intensity level of the lighting with red light below a threshold, at or above which threshold photosynthesis is dominant; and- an intensity level of the auxiliary lighting with far red light between one and ten times the intensity level of the lighting with red light.

2. The method as claimed in clam 1, wherein the initial rooting period is between five and ten days.

3. The method as claimed in claim 1 or 2, wherein, in the initial rooting period, the threshold of the lighting is at 50 pmol / m2 / s, the intensity level of lighting with red light is between 30 and 50 pmol / m2 / s and the intensity level of auxiliary lighting with far red light is between 40 and 100 pmol / m2 / s.

4. The method as claimed in any preceding claim, further comprising, in the initial rooting period, monitoring at least one of root development and cutting stem elongation, and terminating auxiliary lighting with far red light, when a desired root development or stem elongation has been reached.

5. The method as claimed in claim 4, wherein the monitoring comprises deployment of a camera and estimating root development or stem elongation from captured images.

6. The method as claimed in clam 4 or 5, comprising at least once within the initial rooting period, identifying longest or most elongated stems and transferring the longestor most elongated stems from lighting with the red light and the auxiliary lighting with the far red light.

7. The method as claimed in claim 4, 5 or 6, further comprising terminating auxiliary lighting with far red light at a stem elongation of 20%.

8. The method as claimed in any preceding claim, further comprising, after the initial rooting period of lighting the seedlings or cuttings with red light and auxiliary lighting with far red light, in a subsequent period of at least four days up to twelve days of the propagation phase: lighting the seeds or cuttings with red light and complementary lighting with blue light, wherein complementary lighting with blue light replaces auxiliary lighting with far red light of the initial rooting period, and wherein complementary lighting with blue light in the subsequent period is provided in a same intensity level as the auxiliary lighting with far red light in the initial rooting period.

9. The method as claimed in claim 8, wherein, in the subsequent period, the total intensity level of lighting with red light and complementary lighting with blue light is between 100 and at least 150 pmol / m2 / s.

10. The method as claimed in claim 8 or 9, wherein the complementary lighting with blue light in the subsequent period has an intensity of at least 20% of the combined lighting and complementary lighting.

11. The method as claimed in any preceding claim, wherein, in the initial rooting period, the seedlings or cuttings are maintained at about 27°C.

12. The method as claimed in any preceding claim, wherein, in the initial rooting period, the seedlings or cuttings are maintained at a humidity between 80 and 90%.

13. The method as claimed in any preceding claim, wherein, in the initial rooting period, the seedlings or cuttings are placed on a wet substrate, selected from a group comprising stone and glass wool.

14. The method as claimed in any preceding claim, comprising, in the initial rooting period, refraining from irrigation during at least approximately five days from the beginning of the initial rooting period.

15. A horticultural lighting system configured to illuminate cannabis seedlings or cuttings during a propagation phase of young plants, with the system comprising:- an irradiation system for irradiating seedlings and / or cuttings; and- a data processing system in controlling communication with the irradiation system and comprising at least one processor, wherein the processor is configured to control the irradiation system to: illuminate the seeds or cuttings by lighting with red light and auxiliary lighting with far red light during an initial rooting period in the propagation phase of at least four days up to eleven days with an intensity level of lighting with red light below a threshold, at or above which threshold photosynthesis is dominant, and an intensity level of the auxiliary lighting with far red light between one and ten times the intensity level of the lighting with red light.

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