Effects of Cutting Time and Low-temperature Treatment of Rooted Cuttings on Stem Elongation and Leaf Number in Cultivars of Chrysanthemum morifolium Ramat.

The effects of cutting time and low-temperature treatment of rooted cuttings on stem length and leaf number after planting were investigated in ten Chrysanthemum cultivars. Rooted cuttings propagated from mother plants on three different dates (September 30, November 10, and December 14) were planted two weeks after cutting and grown at constant temperatures of 20°C (7:00–19:00) and 12.5°C (19:00–7:00) under long days. In addition, rooted cuttings treated at 2.5°C for six weeks were planted on October 14 and November 24. The ten cultivars could be divided into three groups based on the increased stem length (ISL) of the rooted cuttings five weeks after planting. In five of ten cultivars, the ISL of rooted cuttings decreased from the first cutting date to the second cutting date, and increased from the second cutting date to the third cutting date. In three of the ten cultivars, the ISL of rooted cuttings increased progressively from the first cutting date to the third cutting date. The ISL and increase in leaf number of the rooted cuttings receiving low-temperature treatment were higher than those of untreated cuttings in all cultivars. The capability for stem elongation is apparently reduced by either of two types of temperature-related factors; high temperature followed by low temperature, and the other is high temperature only or high temperature followed by a short period of low temperature.