Growth and Flowering by Relighting and Daminozide Treatment in the Flower Bud Formation Stage of Chrysanthemum morifolium ‘Baekma’ Cut Flowers

This study was conducted to examine the effects of relighting and daminozide treatment on growth and flowering characteristics, length of cut flowers, upper leaf size, and peduncle length in the flower bud formation stage of Chrysanthemum morifolium ‘Baekma’. Relighting for 4-8 hr at 10 days after transition to short-day conditions increased the length of cut flowers, number of leaves, flower diameter, and fresh weight of flowers compared to the control. The upper leaf area was biggest after relighting for 8 hr than in the other treatments. However, relighting for 4-8 hr was not effective for increasing the number of ray florets and delayed flowering by 6-8 days. The two daminozide treatments at 18 (stage I) and 28 (stage II) days after transition to short-day conditions shortened the length of cut flowers, but number of leaves and fresh weight of cut flowers increased in all other daminozide treatments. The peduncle length was longest in the control and was 2.6-3.2 cm in one treatment with 800 mg·L -1 daminozide and two treatments with 400 and 800 mg·L -1 daminozide regardless of stage. The upper leaf area was the smallest in control and biggest in one treatment with 800 mg·L -1 daminozide at stage I and two treatments with 400 mg·L -1 at stage I and 800 mg·L -1 daminozide at stage II. The flower diameter and fresh weight were greater in daminozide treatments than in the control. The number of ray florets increased by 9-11% in one treatment with 800 mg·L -1 at stage I or 400 mg·L -1 daminozide at stage II but decreased in two treatments of daminozide. The days to flowering were delayed by 2-6 days in daminozide treatments than in control. Therefore, it is suggested that relighting for 8 hr at 10 days and treatment of 800 mg·L -1 daminozide at 18 days after transition to short-day conditions are effective in improving the quality of cut flowers by shortening the peduncle length and increasing the growth of the upper leaf area, the length of cut flowers, and the flower diameter. Additional key words: days to flowering, peduncle length, ray florets, short-day condition, upper leaf size