Abstract

Plants require light for photosynthesis and to control many hormonal and morphological changes in the cellular system, with specific colors of light resulting in improved photosynthesis. Changes in the wavelength spectrum have resulted variations in plant biomass production and morphology due to perturbations in the ratio of red/far-red spectrum and effect of blue light. The effects of red and blue light can be partially explained through the regulatory role of two plant photoreceptors, phytochromes and cryptochromes, respectively. However, the primary purpose of light is to drive the chemical reactions within the plant through photosynthesis which is determined by the absorbance characteristics of chlorophyll a and b, as well as the carotenoids, lutein and β-carotene. Higher intensities of wavelength of light exciting these pigments result in efficient photosynthesis, but specific absorbance peak does not always correlate with the maximum quantum yield of photosynthesis as well as plant production. This chapter describes the role of LEDs along with their spectral quality on photosynthesis, development of photosynthetic apparatus, and subsequent plant growth.