Effects of Red and Blue Light with Supplemental White Light on Growth, Carbohydrate Metabolism, and Yield of Virus-Free Potato in Plant Factories

Abstract

The light spectrum has a strong effect on potato tuber development. To investigate the effect of varying the spectrum on potato tuber growth and yield, potato plantlets were transplanted under red/white light (RW; red light: 200 μmol m−2 s−1; white light: 100 μmol m−2 s−1), blue/white light (BW; blue light: 200 μmol m−2 s−1; white light: 100 μmol m−2 s−1), and white/red/blue light (WRB; white light: 100 μmol m−2 s−1; red light: 100 μmol m−2 s−1; blue light: 100 μmol m−2 s−1) with a 11/13-h (light/dark) photoperiod. Potato plants grown under RW had the highest mean fresh tuber weight and total yield among all treatments. Plants under RW resulted in the highest shoot dry weight at 30 d and 45 d among all treatments, providing a photosynthetic source for the tubers. Furthermore, the photosynthetic leaves under RW had a significantly higher total chlorophyll content than other treatments at 90 d. Plants under RW significantly increased tuber fresh weight per plant by 57.7% from 60 to 90 d. The spectrum of BW benefited potato bulking. Plants under BW at 40 d resulted in significant sucrose and starch changes between day and night compared with those at 20 d. BW had a positive effect on the activities of ADP-glucose pyrophosphorylase at 40 d and sucrose synthase at 60 d compared with RW and WRB during the day. Thus, the ratio of tuber (fresh weight of tuber ≥2.0 g) under BW was significantly higher than that under RW and WRB. The total yield of tubers under WRB was the lowest among all treatments.