2009 Volume 8 Issue 3 Pages 309-314
Long-day treatment by pre-dawn lighting (6 h) was applied to Eustoma grandiflorum cultivars to investigate flowering responses and cut flower qualities for early-autumn shipment. Seedlings were irradiated by using bulb-type red-light fluorescent lamps, that R : FR ratio was 8.8, with photon flux density (PFD) of red-light (660±30 nm) of 0.1, 0.2 or 0.5 μmol·m−2·s−1. Control plants were grown under ambient day conditions of 14–15 h without long-day treatment. The times from planting to flower budding under long-day treatments were significantly longer than that of the controls. However, there was no significant difference among the times from planting to flower budding in each treatment. Long-day treatment with the highest red-light intensity showed the greatest increase in the number of nodes on the main stem at anthesis of the first floret. The stem lengths of plants grown under long-day treatment with red-light intensities above 0.2 μmol·m−2·s−1 were significantly longer than that of the control. Long-day treatment using bulb-type red-light fluorescent lamps was applied to 11 Eustoma cultivars. Compared with those of control plants, the times from planting to flower budding under long-day treatment were longer in 9 cultivars and the number of nodes on the main stem at anthesis of the first floret was increased to a maximum of 2.4 in 10 cultivars. Moreover, cut flower length under the long-day treatment was 11.3 cm longer at maximum and cut flower weights were increased in 9 cultivars at harvest (at anthesis of the third floret) compared with those of the controls. The increase in the number of nodes on the main stem under long-day treatment was significantly correlated with the days to flowering in the controls.
