High relative humidity mitigates the adverse effects of excessive light by protecting photosynthetic machinery in flowering Chinese cabbage.

Increasing canopy relative air humidity (RH) facilitates the resistance of flowering Chinese cabbage plants against excessive light exposure in a plant factory with artificial lighting (PFAL), thereby completely inhibiting leaf burn occurrence. To clarify this high RH-mediated resistance mechanism, we further analyzed the transcriptomes, gas exchange parameters, and chlorophyll fluorescence of flowering Chinese cabbage plants subjected to two levels of canopy RH (70% and 90%). Transcriptomic data revealed a significant enrichment of photosynthesis antenna proteins pathway, which was notably downregulated in both the cotyledons and the first true leaves of the plants grown at 70% RH from the 10th to the 14th day after sowing.