Potato Tuber Growth and Yield Under Red and Blue LEDs in Plant Factories

To investigate the effects of red and blue light on potato growth and yield, potato plantlets were transplanted under white (W), red (R), blue (B), and red + blue (RB; 50%R + 50%B) light in growth chambers. Plants under W had a significantly lower tuber yield per plant than the other treatments, although their shoot dry weights were the highest among all treatments. Potato plants under R had the highest tuber yield per plant among all treatments. The distribution of tuber yield under R showed a lower ratio of 2–20 g tubers and a higher ratio of > 20 g tubers, compared to tubers under W. Plants under R had greater leaf dry weight and slowly decreasing total leaf area compared to other treatments in the late stage of potato growth, thereby extending active tuber bulking under R. Although plants under B and RB did not significantly differ in tuber yield per plant, tuber bulking under B and RB occurred in different ways. Plants under RB advanced tuberization in the seedling stage, while tubers under B rapidly accumulated biomass in the medium stage. Plants under B had higher sucrose transport from leaves to sinks and stronger tuberization signals in tubers than those under W. Tubers under B had significantly increased levels of ADP-glucose pyrophosphorylase and sucrose synthase to promote starch biosynthesis, compared to tubers under W. Overall, red light increased tuber biomass accumulation, while blue light rapidly promoted tuber bulking.