BRIEF EXPOSURES OF ULTRAVIOLET-C (UV-C) IRRADIATION IMPROVES FLOWERING OF ORNAMENTAL PLANTS
Ultraviolet-C (UV-C) irradiation has only been tested after harvest as a defense inducible biological elicitor in horticultural products including cut flowers. However, no previous research was found testing the UV-C irradiation on ornamental plants during cultivation. In the present study, geranium (Pelargonium × hortotum), New Guinea impatiens (Impatiens hawker) and petunia (Petunia hybrid) plants were cultivated either inside or outside greenhouses and received on a weekly basis low doses of UV-C irradiation ranging from 0.5 to 10.0 kJ/m2. Positive flowering and growth responses were recorded for geraniums, impatiens, but not for petunias. Exposing geranium plants of the cultivar Glacis with 2.5 kJ UV-C/m2 increased the number of lateral stems and the number of inflorescences by 64 and 75%, respectively. Likewise, applying 1.0 kJ UV-C/m2 to impatiens resulted in 61% increase in the number of inflorescences formed by the end of the 8-week cultivation period. In contrast, petunia suffered severe burns when irradiated with doses ≥2.5 kJ/m2. Lower doses of 0.5 or 1.0 kJ/m2 negatively affected the number of flowers developed and both the horizontal and the vertical plant diameters and, therefore, the overall plant size. We suggest that treatments with UV-C might facilitate production of certain ornamental species in commercial glasshouses in a cost effective and environmentally friendly way.
Darras, A.I., Demopoulos, V., Bali, I., Katsiloulis, O. and Kratimenou, E. (2013). BRIEF EXPOSURES OF ULTRAVIOLET-C (UV-C) IRRADIATION IMPROVES FLOWERING OF ORNAMENTAL PLANTS . Acta Hortic. 1002, 95-101
flowering, geranium, growth, New Guinea impatiens, Petunia