ISHS Acta Horticulturae 418: III International Symposium on Artificial Lighting in Horticulture
EFFECT OF LIGHT INTENSITY ON GROWTH AND QUALITY OF CUT ROSES |
| Authors: | Hans R. Gislerod, Leiv M. Mortensen |
| Abstract:
The yield and quality of different cultivars of greenhouse roses grown under different levels of supplementary lighting up to 370 μmol.m-2s-1, PPF, were studied. The highest light levels contributed to a photosynthetic active radiation which exceeded the natural radiation during summer. Generally the yield increased as the PPF increased up to 370 μmol.m-2s-1, which was given for 20 h a day from September to June. During the summer period the yield increased with 40–50 % given 210 μmol.m-2s-1 when the natural light inside the greenhouse decreased below 300 μmol.m-2s-1. The percentage class 1 roses increased by increasing the PPF up to 250 μmol.m-2s-1, particulary in mid-winter. The percentage of long-stem roses (> 40 cm) was significantly increased by PPF up to 370 μmol.m-2s-1 during winter, but decreased by lighting during summer. The dry weight per shoot or weight per cm stem increased as the PPF increased during winter. | |
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