Abstract
To evaluate rosetting characteristics under artificial conditions in growth chambers, seedlings of 13 Eustoma grandif forum (Raf.) Shinn. cultivars were grown in 5 different day/night temperature regimes (14h photoperiod, 100μmol⋅m-2⋅s-1 PPFD) . Evaluated bolting rates (EBRs) decreased with temperature and differed among cultivars. Rosette indexes (RIs) in the growth chambers were higher than those in the greenhouse. However, close correlations were found between the RIs in the growth chambers and the greenhouse (r=0.856) . These results indicate that it is also valuable to evaluate rosetting characteristics of Eustoma cultivars under artificial conditions and to classify them based on the RIs obtained there. To examine the effect of daylength on the bolting, seedlings of six Eustoma cultivars were grown under two artificial photoperiodic conditions kept at 30°C day/20°C night (100μmol⋅m-2⋅s-1 PPFD) . The photoperiods of short day (SD) and long day (LD) conditions were 12h and 12h+4 h night break (22: 00-2: 00), respectively. LD promoted Eustoma bolting. Both easy- and hardly-bolting cultivars were little affected by the daylength. In the cultivars classified into the intermediate ranks of rosetting, the bolting was stimulated by the night break (LD) .
