Light intensity affects on medicinal compound ajoene accumulation in hydroponically grown garlic plants

Light is important for precise management of plant physiological responses and important secondary metabolite production. The objectives of this study were to determine the effects of different light intensities on tissue biomass and secondary metabolite ajoene accumulation in garlic. In this experiment, hydroponically cultured garlic plants were grown under light treatments of 75, 200, 300, and 460 molm-2s-1. Maximum fresh and dry mass accumulation per plant were observed under 460molm-2s-1 light level. The transpiration rate, stomatal conductance, and relative chlorophyll content at 460 mol·m-2·s–1 were 1.6, 2.1, and 1.3 times greater, respectively, than those at 75 mol·m-2·s–1 light level. The accumulation of ajoene concentration was significantly increased with increasing light intensity from 75 to 300molm-2s-1. Maximum accumulation of ajoene concentration (975.3 g/g), on a fresh mass basis, occurred under 300molm-2s-1 light level but highest ajoene content (33.3 mg/plant) was observed at 460molm-2s-1. Lowest accumulation of ajoene concentration (530.7 g/g) and content (2.9 mg/plant) were observed at 75molm-2s-1 light level, on a freshmass basis. Interestingly, medicinal compound ajoene concentration increased linearlywith garlic dry mass. In conclusion, the biomass accumulation were higher for plantsgrown at 460molm-2s-1 light level but ajoene concentration accumulation were higherfor plants grown at 300 molm-2s-1. There is a strong positive correlation with ajoeneconcentration with dry mass. Identifying effects of light intensity on ajoeneaccumulation in garlic is important information for growers producing this crop for drycapsule supplements and fresh markets vegetables.

Keywords:

Ajoene , Garlic , Hydroponic , Light Intensity