Effects of Plant Height and Cutting Height on Regrowth and Yield of Garland Chrysanthemum Ratooning

Abstract

Garland chrysanthemum is conventionally ratooned and harvested by selective hand picking. This manually intensive mode of harvesting may be improved by adopting mechanized harvesting practices. In view of incorporating machine harvesting into garland chrysanthemum crops, this study evaluated the effects of plant and cutting height on ratoon crop regrowth. Garland chrysanthemums were horizontally harvested using six combinations of three plant height levels at harvest (20 cm, 30 cm, and 40 cm) and three cutting height levels (5 cm, 10 cm, and 15 cm) over three repeated harvests. Plant height at harvest as well as the cutting height affected the total ratooning yield and regrowth process. If plant heights at harvest were low (20 cm) or cutting height relative to plant height at harvest was excessively high, yields decreased. Higher plant heights at harvest and lower cutting heights resulted in longer regrowth periods. Evaluation of branch structures revealed that low cutting heights decreased the number of branches and nodes remaining for regrowth. If the plant height at harvest was low (20 cm), node numbers tended to decrease. Excessively high cutting heights relative to plant height at harvest potentially results in the harvest of immature leaves and stems. We determined that harvesting at 30 cm plant height with 10 cm cutting height was suitable for ratooning, and resulted in high yields. This combination resulted in a sufficient number of first lateral branches and nodes on the plants, thus enabled the harvest of fully grown leaves.