Abstract
Eustoma grandiflorumseedlings become rosetted under high temperature conditions. This characteristic varies among cultivars. To classify 241Eustomacultivars based on their rosetting characteristics, the bolting rates were checked weekly after sowing in May, June or July. When seeds were sown in May, the bolting rate was generally higher, but in June sowing, bolting rates ranged from high to low values. The bolting rate in July sowing was the lowest. Abnormal bolting was observed in all of the three sowing months. In evaluating bolting rate, the bolting rate of abnormally bolted seedlings was multiplied by 0.5 and that of rosetted ones was regarded as 0. Based on the calculated rosette index using this evaluated bolting rate, we ranked all the 241 cultivars as A-E (rosette index : A<20, 20≤B<40, 40≤C<60, 60≤D<80 and 80≤E) . As a result, 17, 35, 122, 56 and 11 cultivars were ranked as A, B, C, D and E, respectively.
