Night break treatment was applied to Eustoma grandiflorum 'Neilpeach Neo' using different light sources to investigate growth and flowering responses. The seedlings were grown in a greenhouse and treated with night break treatment using a far-red fluorescent lamp, a plant growth fluorescent lamp, a daylight-type fluorescent lamp or an incandescent lamp, or were grown under non-treated conditions (control). Photosynthetic photon flux density (PPFD) at the top of the plant was 5 µmol·m −2 ·s −1 under each light source. The red (660 ± 30 nm): far-red (730 ± 30 nm) ratio of the light sources was 0.01, 0.43, 5.00, and 0.65, respectively. The time from planting to flower budding was 46 days for plants grown under a far-red light fluorescent lamp, compared with 66 days in the control. The incandescent lamp and plant growth fluorescent lamp also reduced the time to flower budding; however, the daylight-type fluorescent lamp delayed flower budding by 4 days compared with the control. The light source regimes had little or no effect on the time to flowering after flower budding. The far-red fluorescent lamp, incandescent lamp and plant growth fluorescent lamp reduced the number of nodes on the main stem at the anthesis of the first floret, while the daylight-type fluorescent lamp increased the number of nodes. The farred fluorescent lamp and incandescent lamp promoted internode elongation, while the daylight-type fluorescent lamp reduced internode length. Moreover, a red fluorescent lamp with a R: FR ratio of 105 delayed flower budding and flowering, and increased the number of nodes of the plants as compared with the control, regardless of the long day lengths in July and August. Thus, it is considered that the growth and flowering time of Eustoma grandiflorum can be controlled by long-day treatment carried out with the proper type of light source.

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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. Key Words：cut