Horticultural Science and TechnologyISSN:1226-8763(Print) 2465-8588(Online)원예과학기술지

The aims of this study were to analyze dynamic stem elongation of standard cut-chrysanthemum (Dendranthema grandiflorum) with different photoperiod levels. Standard cut-chrysanthemum cv. Baekma was grown at a 16 hr photoperiod until 23 days after planting, after that different photoperiods of 8, 10, 12, 14, and 16 hr (8H, 10H, 12H, 14H, 16H) were applied using fluorescent lights in a plant factory. The long-day treatments of 14H and 16H produced no flower buds and the 8H treatment was significantly delayed in flower budding initiation compared to the 10H or 12H treatments. The final characteristics of plant height, plant fresh weight, and number of internodes in the 14H and 16H treatments were significantly higher than in the other treatments. Plant height was significantly fitted with parameters of maximum stem length (y_asm), relative stem elongation rate (k), and days to reach maximum stem elongation rate (t_inf) in the Gompertz growth model as a function of days after planting. As the photoperiod increased longer than 14H, y_asm was continuously increased, t_inf was delayed in the 12H-16H treatments, and k was increased between the 8H and 12H treatments and decreased with long day treatments. The maximum stem elongation rate (MGR) was 1.15 cm·d^-1 in the 12H treatment, which was the highest stem elongation rate. Plant height and days after planting were translated to relative scales from 0 to 1 and 0 to 1 or 2 respectively. Relative stem length was significantly fitted and described 99% of relative plant height to developmental stage (DVS) with three parameters of maximum relative stem length (y_asm.DVS), relative stem elongation length (k_DVS), and days to reach maximum relative stem elongation rate (t_inf.DVS) in the adjusted Gompertz growth model. y_asm.DVS was no differences between 8H and 12H in short days whereas 14H and 16H were estimated to be 1 and compared to 12H 22% higher at long day treatment. k_DVS was higher in the 14H and 16H treatments than in the 12H treatment, which means the long-day treatment increased growth rapidly to different DVS. t_inf.DVS was estimated to be between 1.143 and 1.224 in the short day treatment and showed the maximum relative growth rate. Maximum growth ratio to DVS was 68% of plant height in 8H, 10H and 12H whereas 14 and 16H were 62% and 63% of plant height reached at t_inf.DVS. Our study suggested that the Gompertz growth model can describe and summarize the dynamic stem elongation pattern of standard cut chrysanthemum ‘Baekma’ and it is advisable to use a 14H photoperiod in long-day conditions and a 12H photoperiod in short-day conditions during the cultivation of ‘Baekma’.