Abstract - Pennsylvania State University

Stem cuttings of five tree species from dry and semi-arid woodlands (Acacia torti/is, Prosopis juliflora, Terminalia spinosa, Terminalia brownii and Albizia guachapele) and seven species from moist tropical forests (Cordia alliodora, Vochysia hondurensis, Nauclea diderrichii, Ricinodendron heudelotii, Lovoa trichiliodes, Gmelina arborea, Eucalyptus deglupta) have been easily rooted in improved lowtechnology, high humidity polythene propagators in Kenya, Cameroon, Costa Rica and Britain. These propagators, which are cheap to construct, are very effective and have no essential requirements for either piped water or an electricity supply. Experiments have tested different rooting media, auxin applications and compared mist versus non-mist propagation.

Assessments of the physical and gaseous environment of the propagators has indicated ways of improving the rooting environment through an understanding of the sensitivity of the relative humidity to radiant energy and to opening the propagator for short periods (eg 2-3 minutes).