Spectral Composition of Light Affects Sensitivity to UV-B and Photoinhibition in Cucumber

Ultraviolet B (UV-B) (280–315 nm) and ultraviolet A (UV-A) (315–400 radiation comprise small portions of the solar but regulate many aspects plant development, physiology metabolism. Until now, how plants respond to UV-B in presence different light qualities is poorly understood. This study aimed assess effects a low dose (0.912 ± 0.074 kJ m –2 day –1 , at 6 h daily UV exposure) combination with four treatments (blue, green, red broadband white 210 ?mol s Photosynthetically active [PAR]) on morphological physiological responses cucumber ( Cucumis sativus cv. “Lausanna RZ F1”). We explored quality backgrounds morphology, leaf gas exchange, chlorophyll fluorescence, epidermal pigment accumulation, acclimation ability saturating intensity. Our results showed that supplementary significantly decreased biomass accumulation broad band white, blue green light, not under light. also reduced photosynthetic efficiency CO 2 fixation (?) when combined These plants, despite showing high anthocyanins, were unable cope conditions. No significant observed for exchange fluorescence parameters, increased flavonol contents epidermis. Plants grown maximum rate dark respiration compared pure Additionally, treated exposed intensity higher quantum yield photosystem II (PSII), fraction open PSII centres electron transport no effect apparent photochemistry (F v /F ) or non-photochemical quenching, contrast solely red-light findings provide new insights into spectra.