4.3. Effect of photoperiod on growth and flowering
In the first experiment, the TDC plant height significantly
increased at the time to first flower opening under longer photoperiods compared with SDs (10 h and 12 h) (Table 1). Zaccai and
Edri (2002) found that the stem length of lisianthus ‘Heidi Deep
Blue’ was enhanced under the LD treatment at day 60 when grown
in either winter or summer. A similar increase in stem length was
also found in C. lanceolata when exposed to an inductive LD treatment (Damann and Lyons, 1993). The significant increase in stem
length or plant height under LD conditions may be due to the longer
time for carbohydrate production through photosynthesis or may
be due to an increase in endogenous GA, similar to Arabidopsis
plants (Hedden, 1999).
Our results showed that the leaf number decreased under inductive LDs compared with SDs. The node number is equivalent to the
leaf number. In other reports, in addition to the faster floral transition under LD, the decrease in node number on the main stem at
Fig. 3. Correlation between flower differentiation phase (DP) and leaf number, plant height, weeks after sowing, crown diameter