Lichtregimes

Lichtregimes (light regimes) describe the pattern of light exposure that organisms experience in a given environment. In plant science, a lichtregime encompasses the quantity (intensity), quality (spectral composition), duration (photoperiod), and timing of light and dark periods, as well as seasonal and daily fluctuations. The term covers both natural conditions, such as daylight changes under a forest canopy, and artificial setups, such as growth chambers or greenhouse programs that specify light spectra and photoperiods.

Key components include photosynthetically active radiation (PAR), measured in micromoles of photons per square meter per second, and the daily light integral (DLI), the total PAR received per day. Light quality refers to the balance of wavelengths, with blue and red light often having strong effects on photosynthesis and development. The photoperiod, the length of day versus night, regulates processes such as flowering or dormancy in many species through photoperiodism. Temporal dynamics, including dawn and dusk transitions and short-term fluctuations, can influence physiology and behavior.

Ecologically, lichtregimes shape primary production, competition, and habitat structure, and organisms may acclimate to different regimes through adjustments in pigment composition, leaf anatomy, and circadian regulation. In research and production, scientists and growers design and implement lichtregimes to study responses or optimize growth, yields, or developmental timing. Understanding lichtregimes thus links physical light properties with plant biology and ecosystem dynamics.