PROPAGATION OF HIBISCUS ROSA-SINENSIS: RELATIONS BETWEEN STOCK PLANT CULTIVAR, AGE, ENVIRONMENT AND GROWTH REGULATOR TREATMENTS
Cuttings from stock plants grown under low irradiance daylight were rooted in perlite under intermittent mist for 30 days supplemented with 70 to 320μE m-2 s-1 PPFD from SON T lamps during the winter months in Denmark (6 to 7 hours daylength approx. 40μE m-2 s-1 PPFD).
Three cultivars selected on the basis of their performance in previous investigations reacted differently towards auxin (IBA) treatments: In 'Holiday' and 'Casablanca' root numbers were doubled while no significant effect was evident in 'Red rosa-sinensis'. With older stock plants, cutting production was reduced and the cuttings rooted less even with IBA treatment.
Stock plant growth and thus cutting production was enchaced by suplemental irradiance. Leaf area and weight of cuttings of similar developmental stage (2 ½ leaf), increased considerably while the length of the third internode (cutting base) was unaffected by irradiance in the poorly rooting cv. 'Casablanca'. Rooting was enchanced by IBA and by irradiance to stock plants.