Measuring light spectrum as a main indicator of artificial sources quality

Abstract

Light is one of the most important environmental factor for plant growth. The intensity and quality of light are essential for growth, morphological features and other physiological responses of plant[1]. The most important process, which is dependent on light, is photosynthesis. It is a process by which the physical energy of light is used to convert chemical substances to a more energetic state. The energy of a photon of light is captured by substance pigment, formation of an electronic excited state and use to reduce an acceptor substance, which is used to form other, complex organic molecules[2]. However, not all solar radiance is used by plants. Photosynthetically active radiation (PAR) is a solar radiance available for plant and it occurs in spectral band from 400 to 700 nm wavelength. Plant pigments, chlorophyll and carotenoids absorb PAR best at specific wavelength. Chlorophyll a has a peak spectral absorption at 430, 460 and 660 nm. Chlorophyll b absorb most effectively at 430, 455 and 640 nm. Carotenoids, including xanthophyll absorb most effectively in bands near 450 nm[3]. Considering the above, PAR can be divided into high active and low active wavelength based on pigment absorption bands. PAR in range from 400 to 500 nm, called blue light affect many aspects of plant growth and development, including inhibition of hypocotyl elongation, stimulation of cotyledon expansion, regulation of flowering time, phototropic curvature, stomatal opening, entrainment of the circadian clock and regulation of gene expression[4]. The light from 600 to 700 nm (red light), are active for photosynthesis, photomorphogenesis, and chlorophyll synthesis[3]. Under red light, ARTICLE INFO ABSTRACT