Effects of auxins and light quality on rooting of chrysanthemum cuttings
This research was conducted in response to the concerns of pot chrysanthemum growers regarding poor anchorage of plants. The effects of quick (3 sec) and long (3 min) dip methods for two auxins (IBA and NAA), as well as photoperiodic light quality (R/FR) during night interruption and total non-structural carbohydrates (TNC), on rooting were studied with a difficult-to-root 'Duluth' and an easy-to-root 'Presidio' cultivar. The long-dip method at low concentrations produced comparable results (height of root formation, root length, roots surface area) to the short-dip method at higher concentrations, and both were better than the controls. Duluth was positively responsive to IBA whereas 'Presidio' responded positively to NAA. Growth of stock plants with high R/FR photoperiodic night lighting positively affected root length, number of roots and root surface area in 'Presidio' but not in 'Duluth'. The TNC concentration of stock plants was significantly higher under high R/FR lighting with 'Duluth' accumulating more TNC than 'Presidio'. Moreover, the high R/FR night lighting of stock plants and rooting produced significantly shorter plant in both cultivars. The results of this research suggest that anchorage of chrysanthemums in pots can be improved by using liquid auxin formulations and substituting incandescent lamps with compact fluorescent lamps for photoperiodic night interruption.