Shoot growth and physiological disorder of cut rose 'charming black' as affected by drought stress during nocturnal supplemental lighting

Cut rose 'Charming Black' was subjected to three treatments to investigate whether a no-irrigation regime causes drought stress during nocturnal supplemental lighting, and to investigate the effect of drought stress on the growth and quality of the cut flower. During the experiment, shoot length, quality of flower, photosynthetic rate, and chlorophyll and carotenoid contents were measured. Supplemental lighting treatment group grew faster and decreased the percentage of blind shoot; however, several physiological disorders were appeared under different environment conditions. In supplemental lighting (90 μmol·m^-2·s^-1 PPFD) treatment group, the shoot grew well and flowered early with irrigation once per hour, but drought stress and a decrease in biomass occurred without irrigation. Water deficit in the no-irrigation regime under supplemental lighting affected the plant growth and caused malformation of the flower. Drought stress also had a negative effect on the photosynthetic machinery with a reduction in carotenoid and chlorophyll contents. As a result the photosynthetic rate was also decreased.