Effects of different light spectra on high light stress tolerance in rose plants (Rosa hybrida cv. ‘Samurai’)

Roses are the most famous ornamental plants worldwide. Light is considered as one of the most important environmental factors that influences the production of rose plants. Low or high light intensities can reduce photosynthesis and growth of rose plant. In this study, using chlorophyll a fluorescence and OJIP test, which is a detailed method for analyzing the efficiency of photosynthesis in the plant, effects of different light spectra on photosynthesis and their subsequent influence on high light stress were investigated. Experiment was carried out with four growth chambers [including red (R), blue (B) 70:30% red: blue (RB) and white (W)], in the spring of 2017 in the greenhouse of Aburihan Campus, University of Tehran. Following growth of plants for one month under different light spectra, the plants were exposed for 12 hr to high light intensity (1500 μmol m-2 s-1). Analyzing polyphasic chlorophyll a fluorescence (OJIP) data showed that highest energy absorption and electron transfer rate per reaction centers were observed in plants that were grown under red light. The highest amount of photosynthetic pigments, anthocyanins, soluble carbohydrates and the lowest peroxidation of membranes and hydrogen peroxide concentration were detected in plants that were grown under red light spectrum. In conclusion, based on the obtained result, red light is efficient to decrease the negative impact of high light stress on rose plants.