Growth Mechanism of Matricaria chamomilla Plant Under Space Lighting System: Induction of Pigment Synthesis, Enzyme Defense System, and Antioxidant Metabolites

Light is a vital factor for plant cultivation. LED lamps in different spectra have some advantages such as low heat production and energy requirement, and long lifespan, which was used for the first time to design plant growth chambers in closed culture systems and space research. In this research, impact of light spectrums was studied on the growth mechanisms through chlorophyll pigments, enzyme defense system, and antioxidant metabolite analyses. Seeds were cultivated in Murashige and Skoog medium and exposed to different light spectrums of white, red, blue, and red-blue. Then, the seedlings were harvested for growth and biochemical analyses after 4 weeks. Results showed that red-blue and blue lights induced the fresh weight, dry weight, root length, adventitious roots, chlorophyll content, protein, flavonoids and antioxidant enzymes of superoxide dismutase and catalase. Blue spectrum significantly decreased stem length and increased the relative water content. Moreover, the highest amount of hydrogen peroxide was observed in seedlings treated with red light. It seems that light spectra by changing the hydrogen peroxide level can regulate antioxidant enzyme activity and enhance antioxidant metabolites, and red-blue light may use as a suitable lighting spectrum for the design of M. chamomilla cultivation chamber in space research.