![]() On the other hand, the control function of light acts as an environmental signalling, perceived by a very sensitive detection system, regulating the plant photomorphogenetic responses, including the transition from a development stage to the next (Devlin et al. 2010 Kono and Terashima 2014 Vialet-Chabrand et al. leaf surface and thickness), to maximize light harvesting and CO 2 capture (Terashima et al. ![]() chloroplast size and distribution) and morphology (e.g. Rubisco content and change in PSII and PSI ratio), leaf anatomy (e.g. Through these mechanisms, plants acclimate to a given light environment by means of adjustments of photosynthetic biochemistry (e.g. 2007).Īs their life depends on the assimilative function of light, plants evolved fine light-sensing mechanisms to maintain and maximize photosynthetic performance and fitness during their life span. Light is one of the main environmental parameters regulating plant physiology throughout the entire plant life cycle, as plants use light as both energy source for carbon fixation in photosynthesis (assimilative function), and signal to activate and regulate many other key processes related to plant growth and development (control function) (Devlin et al. Particularly, we analysed these effects by approaching, when possible, each single-light waveband, as most of the review works available in the literature considers the influence of combined spectra. This article presents a brief overview on the effects of light spectrum of artificial lighting on plant growth and photomorphogenesis in vegetable and ornamental crops, and on the state of the art of the research on LEDs in greenhouse horticulture. This knowledge could be profitably applied in greenhouse horticulture to improve production schedules and crop yield and quality. Knowledge about plant photomorphogenesis increased dramatically during the last years, also thanks the diffusion of light-emitting diodes (LEDs), which offer several advantages compared to the conventional light sources, such as the possibility to tailor the light spectrum and to regulate the light intensity, depending on the specific requirements of the different crops and development stages. These are perceived even at very low intensity by five classes of specific photoreceptors, which have been characterized in their biochemical features and physiological roles. More than providing the energy for photosynthesis, light also dictates specific signals which regulate plant development, shaping and metabolism, in the complex phenomenon of photomorphogenesis, driven by light colours. The famous physicist Richard Feynman came up with an illustration of why intensities drop as the square of the distance by imagining buttering bread using a "butter gun.Light quantity (intensity and photoperiod) and quality (spectral composition) affect plant growth and physiology and interact with other environmental parameters and cultivation factors in determining the plant behaviour. ![]() intensity of sound (although we hear sound on a logarithmic scale in decibels).Some examples of the inverse square law are: d is the distance from the centre (rather than the surface).X is the quantity or intensity (sound, light, electric field).Inverse square laws always look something like this: If it's 10x farther away, the radiation exposure is 100x less. If the source is 2x as far away, it's 1/4 as much exposure. For example, the radiation exposure from a point source (with no shielding) gets smaller the farther away it is. Specifically, an inverse square law says that intensity equals the inverse of the square of the distance from the source. This means that the intensity of the property decreases in a particular way as the distance between interacting objects increases. Ī number of physical properties (like the force between two charges) get smaller as they get farther apart in a way that can be represented by an inverse square law. Figure 1: The inverse square law can be seen as the force spreading out over an ever increasing area.
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