Subtle changes in solar radiation under a green-to-red conversion film affect the photosynthetic performance and chlorophyll fluorescence of sweet pepper

Although spectrum conversion films are used to improve the photosynthetic efficiency and, ultimately, crop growth, the effects of the modified spectrum on photosynthetic traits in plants have not yet been sufficiently reported. The objective of this study was to investigate the changes in photosynthetic performance and chlorophyll fluorescence of sweet pepper (Capsicum annuum L.) under a green-to-red conversion (GtR) film. The GtR-modified spectrum increased the dry mass and decreased the petiole length. The photosynthetic light-response curves were significantly improved, and the gap of the maximum photosynthetic rates increased over time after covering. The GtR-modified spectrum significantly increased chlorophyll fluorescence parameters in the JIP-test, such as parameters related to the reduction of end electron acceptors on the PSI acceptor side, the efficiency for electron transport in PSII, and the performance indexes. Our data indicated that the GtR-modified spectrum promotes electron transfer around PSI, improving photosynthetic performance and growth.