간헐적 조명 조건이 상추의 생장 및 광합성 적응 반응에 미치는 영향

초록

Light is a critical environmental factor regulating photosynthesis, growth, and morphogenesis in plants; however, beyond total light quantity, the temporal configuration of light-dark cycles play an important role in determining growth performance. This study investigated lettuce growth responses and photosystem II (PSII) photosynthetic adaptation under different photoperiod conditions (L12/D12, L6/D6, and L1/D1). Growth parameters, including fresh weight, leaf area, and plant height, were highest under the L12/D12 photoperiod, whereas the L6/D6 treatment showed significant growth suppression throughout the experimental period. The L1/D1 treatment maintained an intermediate level of growth. Chlorophyll fluorescence analysis revealed distinct PSII responses among photoperiod treatments. The L6/D6 treatment exhibited a consistent decrease in fluorescence intensity in the J–I–P phase of the OJIP curve, accompanied by reductions in PI, F /F v m, Fv/Fo, RC/CSm, and ETo/RC, indicating impaired PSII function and restricted electron transport capacity. In contrast, the L1/D1 treatment showed increases in early stress-related indices such as ABS/RC, DI /RC, V , and M , while maintaining relatively stable electron transport efficiency and integrated o j o performance indices, suggesting rapid damage-repair cycling under short intermittent light exposure. Under the L12/D12 treatment, PSII parameters remained largely stable throughout the experimental period. Correlation analysis further demonstrated that under the L1/D1 condition, strong relationships were observed for F －F (r = 0.90), V －PI om j (r = －0.37), and M －PI (r = －0.93), highlighting the influence of early electron transport limitations on overall PSII o performance. Under the L6/D6 h condition, strong negative correlations were detected between ABS/RC and PI (r = － 0.81) and between DIo/CS and PI (r = －0.83), reflecting increased energy dissipation and photoinhibition. In contrast, under the L12/D12 condition, strong positive correlations were maintained between F and RC/CS (r = 0.93) and o m between ET /TR and RC/CS (r = 0.82). Overall, these findings demonstrate that photoperiod temporal structure, oo m beyond total light quantity alone, is a key determinant of lettuce growth performance and quality through its influence on PSII adaptive responses. This study provides a physiological basis for optimizing photoperiod design in artificial lighting-based plant factory systems.

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