Lighting in Design Q3 2022

separate control of the FR circuit. This enables the grower to use FR as a tool, either on its own or with broad spectrum white light. How does it work The phenomenon is not new and is known as the Emerson ef fect. Rober t Emerson (1957) found out that plants exposed simultaneously to light of shorter and longer wavelengths then 680 nm, have much more efficient photosynthesis than if they are exposed to only shorter or longer wavelengths separately. It happens because photosynthesis i s dr iven by two photosys tems which work in synergy. It can be compared to two pump mechanisms used to transport energy. The f irst pump or photosystem uses red photons to pump up electrons on a higher level. The second pump or photosystem uses far-red photons to pump up electrons even further. High energy photons are used to synthetize basic building biochemicals which can be used to make different substances e.g. sugars. The efficiency of the system is highest when both pumps work together in a balanced way. Using laser diodes to obtain extremely narrow wavebands, Zhen et al. (2018) found that photons from 703 to 731 nm tended to be more efficient at increasing photochemical efficiency than photons below 703 nm or above 731 nm FR. Photons of wavelength above 752 nm are not ef fective in enhancing photochemical efficiency as they are no longer used by the first photosystem due to low photon energy and absorption. Far-red light increases the ability of plants to capture light Plants use light not only as a source of energy (i.e., in the process of photosynthesis), but also for information about the surrounding environment. Because plant leaves absorb blue and red light ef f iciently while FR light is mostly ref lected or filtrated, the light under a plant’s leaves contains propor tionally more far-red and less blue and red light than direct sunlight. An increase in the proportion of FR photons in the growth spectrum is therefore perceived by plants as information that they are shaded and at risk of being overgrown by other plants. In response they will try to get taller, i.e., extend their stem and leaf petioles, to overgrow the competition. Some plants can also try to increase their light capture by increasing leaf area and reducing production of sunscreen type pigments (anthocyanins). Plants with a taller, looser canopy will also capture more light when compared with those hav ing more compac t form. Because they dedicate most of the avai lable resources to extension growth, shaded plants reduce branching and decrease production of some biochemical compounds. Some species may also react to shade by flowering as soon as possible to produce seeds

What is PPF? Photosynthetic Photon Flux (PPF) is the term we use to define the measurement of PAR. Its underlying value determines how much PAR your LED grow lights can produce per second. The PPF measurement helps you understand how much of the light your fixtures are producing, which can be used by your marijuana plants for photosynthesis. PPF is measured in micromoles per second or “µMol /s”, where one mi cromole i s equal to approx imate l y 602 quadr i l l ion photons . Measuring your PPF properly requires a thorough understanding of the process and a little bit of mathematical subtleness and patience. And while there are PPF measurement tools that can be purchased from the open market, you might work with a trusted partner who can help you choose the perfect LED grow lights that are efficient enough to provide the desired PAR and PPF. What i s PPFD? Photosynthet i c Photon Flux Density (PPFD) is the third and f inal part of the PAR equation. PPFD is the intensity of PAR light that lands on a square metre each second. It is measured in micromoles per square metre per second (μmol ·m-2·s-1) PPFD is how much PPF is hitting each square metre of your crop at any given second. Far-red (FR) light is a waveband at the extreme end of the visible light spectrum. It is regarded as wavelengths between 700 and 780 nanometers (nm). To human eyes, FR is only dimly visible, but it plays a very important biological role for plant growth and yield. FR has long been cons idered to have a minimal input in photosynthesis and is excluded from the definition of Photosynthetically Active Radiation (PAR; 400 to 700 nm). It is because the photosynthetic ef f iciency of monochromatic FR light sharply declines with the wavelength. FR is largely reflected and transmitted by plant leaves, and only about 30% is absorbed. Several recent studies have shown that far-red photons interact with shorter wavelength photons to increase ef f iciency of photosynthesis. Zhen and Bugbee (2020) have studied the effect of FR on whole plant photosynthesis for 14 dif ferent crop species. They concluded that adding far-red photons to a spectrum of shorter wavelengths (e.g., broad white spectrum) caused an increase in canopy photosynthesis equal to adding additional light from PAR range (400-700 nm) of the same intensity. The effect was wavelength dependent. The authors postulated that radiation between 700 and 750 nm should be included in the definition of Photosynthetically Active Radiation (PAR). InDorSun offers the majority of its fixtures with Far-red: The light which plays an important role in plant growth

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LiD Q3 - 2022