Stomatal and non-stomatal limitations of Rosa hybrida 'Pink Bell' under drought stress

The intention of the present review is to investigate the mechanisms underlying the inhibition of photosynthesis during drought stress of the cut rose cultivar 'Pink Bell' grown via soilless cultivation and under supplemental light. When irrigated once per hour, the shoots grew well and flowered early, but without irrigation the roses showed decreases in the biomass and photosynthetic capacity. Both stomatal and non-stomatal factors caused depression of photosynthesis under drought stresses, mainly through stomatal behavior and photochemical and biochemical limitations. In the experiment, supplemental lighting without irrigation (TSL×NI) induced a decline in the net photosynthetic rate (An), stomatal conductance (gs), and stomatal size and density compared with irrigated plants (TSL×I). Drought stresses (TSL×NI) also induced a reduction in rubisco activity, the maximum quantum yield (FV/FM), and the photosynthetic pigments. The analysis established that under drought stresses, stomatal limitation imposes a major limitation on the photosynthetic performance in the morning, however, non-stomatal limitation has negative impacts on photosynthesis in the afternoon.