2008 Volume 7 Issue 4 Pages 571-577
Effects of temperature on node numbers of flower bud differentiation of Gloriosa superba L. were investigated using three genotypes, ‘Misato Red (MR)’, ‘Tropical Red (TR)’ and ‘Rose Queen (RQ)’. Tubers of each genotype were kept at 30°C for 23 days to enhance sprouting, and then were planted in a greenhouse with soil temperature controlled at 19.1±0.6°C or 31.6±1.0°C. Flower buds initiated at the same node order under both temperature conditions in MR and TR, whereas RQ produced larger numbers of leaves at a higher soil temperature. When tubers were kept at 15 to 40°C for 56 days under dry conditions, flower initiation occurred at 30°C or below in MR and at 35°C or below in TR during the temperature treatment, but did not occur in RQ, indicating a longer juvenile phase of RQ. Whereas 30°C was suitable for leaf differentiation, node numbers of flower bud differentiation were smaller at a lower temperature in all genotypes. MR tubers treated at 30°C for 25 days and TR and RQ tubers treated for 15 days followed by 15°C for 15 days showed lower node numbers of flower bud differentiation compared with tubers treated at 30°C for 30 days. Since 30°C enhanced vegetative growth but inhibited flower bud differentiation in Gloriosa, tubers kept at 30°C followed by 15°C showed less vegetative growth. The present results show that genotype differences in node number of flower bud differentiation can be due to the differences in juvenile phase length and temperature-related phase transition.
