Shoot Growth and Flower Quality of Cut Rose ‘Pink Bell’ as Affected by Supplemental Lighting Intensity
pp.131-135
This study was conducted to investigate the effectof supplemental lighting intensity (SLI) on the shoot growthand flower quality of Rosa hybrida ‘Pink Bell’ in winter sea-son. High pressure sodium lamps (HPS) which were set upat 1.4m height above the planting beds were adjusted forthe SLI treatments: no supplemental lighting (control), pho-tosynthetically active radiation (PAR) 30, 50, 70, and 90µmol•m−2•s−1 in 20h daylength (17:00 to 22:00 and 02:00to 09:00). Shoot growth including shoot elongation, shootweight, and flowering speed was promoted quantitatively asSLI increased. But the flower quality such as petal num-bers, petal pigmentation, and biomass distribution to thepetals was declined at PAR 90, even though the proper SLIfor rose production was generally known in the range ofPAR 90 to 120. In this experiment PAR 90 treatment madethe surface of petals heated near 30oC which was about10oC higher than the control group without supplementallighting. The surface temperature of the petals was continu-ously rising because the distance to lamps from floral budsbecame increasingly short as the shoots grew in localgreenhouse facilities. The heat stress by HPS lampscaused petal discoloration and over-consumption of assimi-lation products due to excessive respiration and water lossin petals. Thus, it is necessary to prevent heat injury byswitching light intensity depending on shoot growth consid-ering local greenhouse structure.
Materials and Methods
Plant materials and SLI treatments
Shoot growth and leaf photosynthesis
Heat stress and injury
Statistical analysis
Results and Discussion
Shoot growth and flower quality
Photosynthesis and chlorophyll content
Heat stress and injury
Acknowledgements
References