ISHS Acta Horticulturae 251: III International Symposium on Growth Regulators in Ornamental Horticulture
PROPAGATION OF HIBISCUS ROSA-SINENSIS: RELATIONS BETWEEN STOCK PLANT CULTIVAR, AGE, ENVIRONMENT AND GROWTH REGULATOR TREATMENTS |
| Authors: | Q. Wang, A. Skytt Andersen |
| Abstract:
Vegetative propagation of Hibiscus rosa-sinensis L. is beset by several problems when this species is used as an almost year-round potted plant crop in Northern Europe. The cultivars which have proven popular and easily propagated by cuttings may show seasonal fluctuations in cutting productivity as well as in rooting. The differences between cultivars in propagative propensity is of a high magnitude (Bertram et al., 1987). The rooting reactions of Hibiscus cuttings as well as other species to environmental conditions during stock plant growth led to the initiation of investigations of rooting hormone efficiency under varying stock plant growing conditions. 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. | |
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