Beneficial effects of red and blue light on potato leaf antioxidant capacity and tuber bulking.

Artificial light application is an effective method for promoting potato production in indoor facilities. In this study, we assessed the effects of different combinations of red (R) and blue (B) light application on potato leaf and tuber growth. Potato plantlets were transplanted under W (white light, control), RB (50% R + 50% B), RB (30% R + 70% B to 70% R + 30% B) and RB (10% R + 90% B to 90% R + 10% B), and ascorbic acid (AsA) metabolism in leaves and cytokinin (CTK), auxin (indole-3-acetic acid, IAA), abscisic acid (ABA), and gibberellin (GA) levels in tubers were measured. At 50 days of treatment, potato leaves had significantly higher L-galactono-1,4-lactone dehydrogenase (GalLDH) activity and utilized AsA faster under RB treatment than under RB treatment. CTK/IAA and ABA/GA ratios in large tubers under W treatment did not differ significantly from those under RB treatment, which had higher levels than those under RB and RB treatment at 50 days. However, under RB treatment, total leaf area decreased rapidly from 60 to 75 days compared with plants under RB treatment. Tuber dry weight per plant under W and RB treatment approached a plateau at 75 days. At 80 days, RB treatment significantly improved ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase activity compared with RB treatment. RB treatment with a high ratio of blue light increased CTK/IAA and ABA/GA to improve tuber bulking at 50 days, while RB treatment with a high ratio of red light stimulated AsA metabolic pathway to delay leaf oxidation and maintain tuber biomass accumulation at 80 days. For the indoor potato cultivation, RB treatment had a higher proportion of medium-sized tubers, thus being a suitable light treatment.