Effect of Red and Blue Light on the Growth and Antioxidant Activity of Alfalfa Sprouts

Alfalfa sprouts are popular as a gourmet vegetable that contains a variety of antioxidants with anti-cancer and anti-coronary heart disease properties. In this study, under a photosynthetic photon flux density (PPFD) of 30 mol center dot L-1 photoperiod of 12 h for 3 days, and a temperature of 25 +/- 2 degrees C, we investigated the effects of different light qualities on the growth, nutritional quality and antioxidant activity of alfalfa sprouts by modulating LEDs with different red and blue ratios, and searched for suitable light-quality conditions for alfalfa sprout growth. The experimental results showed that the dark treatment favored the growth of alfalfa sprout hypocotyls and the increase of soluble sugar content; alfalfa fresh weight was the largest under the white and red light treatments; nitrate content was the lowest in the treatment with a red-to-blue ratio of 2:2 (2R2B); soluble proteins and total phenolic content were the highest in the treatment with red-to-blue ratio of 1:3 (1R3B); and the total antioxidant activity of sprouts was the highest in the blue light treatment.