IMPACT OF LIGHT ON CYATHIA ABSCISSION AND BRACT DISCOLORATION IN POINSETTIA (EUPHORBIA PULCHERRIMA)

The role of light in control of cyathia abscission and bract discolouration in poinsettia (Euphorbia pulcherrima) is unclear.
The aim of this work was to study the involvement of photosynthetic photon flux (PPF) and extended photoperiod from 10 to 13, 16 or 24 hours with supplemental lighting at the end of the culture period on development of bract discoloration at marketing stage of the plants, and the postharvest performance of cyathia abscission in interior climate of two poinsettia cultivars, ‘Lilo’ and ‘Millenium’. The plants were grown at different photoperiods with supplemental PPF of 73 and 146 µmol m^-2 s^-1 at plant level.
The extended supplemental light treatments were given for one, two or three weeks at the final cultivation period before marketing stage.
Extended photoperiod from 10 up to 24 h had no influence on discolouration of the bracts as black and greenish areas of the bract in ‘Millenium’. In contrast, ‘Lilo’ developed serious bract discoloration at photoperiods longer than 13 h.
The most serious symptom appeared at 24 h and three weeks of exposure time.
Extended photoperiods with supplemental lighting enhanced cyathia abscission at the end of the culture time and during the postharvest test in interior climate. ‘Millenium’ had a better ability to retain cyathia than ‘Lilo’. It is concluded that poinsettia plants should be grown in a photoperiod not longer than 13 h in order to maintain a low rate of cyathia abscission at the end of the production period and during the first 2-3 weeks in interior climate.

V International Symposium on Artificial Lighting in Horticulture

R. Moe, E. Floistad, D.R. Blystad

photoperiod and supplemental lighting, keeping quality, postharvest

https://doi.org/10.17660/ActaHortic.2006.711.38