Influence of LED light on seed germination, growth, and health-promoting compounds in red and green lettuce cultivars

This study investigated the influence of specific light-emitting diodes (LEDs) on lettuce seed germination, growth, and the accumulation of health-promoting compounds. The results revealed that LED lights significantly impacted both red (Jeok Chi Ma) and green (Cheong Chi Ma) lettuce cultivars and compared to natural light. Red-blue light combinations accelerated germination in the red cultivar, while red light alone had the opposite effect in the green cultivar. Red light enhanced shoot fresh weight (SFW) for both cultivars, with the combination of red-blue light showing promising results as well. Blue light promoted root growth in both cultivars, followed by white light. Red light maximized root length (RL), while blue and white light were most effective for root volume (RV). Blue light significantly increased the levels of health-promoting compounds like phenolic compounds (PCs), anthocyanins (ANTs), and chlorophyll a (Chl a) and chlorophyll b (Chl b) in both cultivars. Red light, on the other hand, maximized carotenoids (CARs) content. Natural light resulted in the lowest levels of these compounds. Blue and red light respectively stimulated the expression of key genes in the ANTs and CARs biosynthetic pathways, with varying responses observed between the red and green cultivars. Overall, this study highlights the potential of utilizing specific LED light wavelengths to optimize lettuce growth and enhance the accumulation of health-promoting compounds. The findings suggest that tailoring light spectrums based on cultivar type can be a valuable strategy for controlled environment agriculture.