Effects of red and blue monochromatic lights on growth, development and physiological characters of hydroponic tobacco seedlings

To provide a basis for optimization of light condition in tobacco seedling greenhouse, the effects of red and blue monochromatic lights on tobacco seedling growth and development were studied with white light treatment as control. Results showed that red light increased leaf area and fresh biomass by 49.8% and 48.8% while blue light curbed the growth of tobacco leaves. Blue light increased stalk height by 59.2% while red light did not. Fresh biomass, 1° and 2° lateral root numbers and root superficial area outweighed those under blue and while light. Content of chlorophyll and carotenoid varied under different light conditions with that under white light being the highest, that under blue light being the lowest and that under white light standing in-between. Net photosynthetic rate and stomatal conductance under red and blue light were slightly lower than those under white light. Blue light inhibited the photosynthesis by decreasing Gs while red light inhibited photosynthesis due to nonstomatal factors.