Effects of LED light combinations on the growth and postharvest stability of barley grass (Hordeum vulgare L.) cultivated in a plant factory system

This study examined the effects of various LED light combinations on the germination, growth, and photosynthetic efficiency of barley grass (Hordeum vulgare L.) cultivated in a plant factory system, and evaluated how different postharvest packaging methods influence microbial dynamics and quality attributes. Treatment with monochromatic red LED (R10) resulted in the highest germination rate (95.3%) and superior growth characteristics, including plant height, fresh weight, and dry weight. The maximum quantum yield of photosystem II (Fv/Fm) also peaked under R10 (0.81), indicating enhanced photosynthetic performance. In contrast, blue-enriched treatments (R3B7 and B10) produced lower Fv/Fm values (0.79), reflecting reduced photosynthetic efficiency. During storage, packaging type exerted a stronger influence on microbial status and weight loss than the LED treatments, with modified atmosphere packaging (MAP) effectively minimizing both moisture loss and microbial proliferation. These findings provide important academic insights by demonstrating the role of LED spectral quality in regulating early growth and photosynthetic responses of barley grass, identifying R10 as an optimal light regime for uniform seedling establishment and biomass enhancement in plant factory environments. Moreover, the MAP system (OTR 40,000) presents strong industrial applicability by improving postharvest quality retention and microbial safety during distribution and storage. Taken together, this study suggests that integrating red-centered LED lighting (R10) during production with optimized MAP conditions can support year-round, stable production and extended shelf life of barley grass in commercial plant factory operations.