Propagation of jojoba (Simmondsia chinensis (Link) Schneider) clones for commercial use is expensive. An investigation was conducted to improve the efficiency of this process. Rooting of semi-hardwood stem cuttings of jojoba was studied beginning on 14 April 1994 (mid-autumn). A factorial study using five clones and five substrates showed significant differences in rooting among clones, but no effect of substrate. When substrate temperature was varied, 20-25 and 27-30 degrees C, an interaction was observed between clone and temperature. Only one of the five clones, the one with the lowest rooting percentage, rooted significantly better than the others at the higher temperature range. In another study using the two clones with the highest and lowest percent rooting in the first study, six substrates (the same five as in the first study plus a 100% sand substrate), and two substrate temperature ranges (10-12 and 20-25 degrees C), significant differences in rooting between these two clones were again observed. Substrates had no significant effects on rooting. In this study, only the rooting of the lowest-rooting clone was increased by heating the substrate. In both studies with temperature differences, rooting of this clone was increased at the higher temperature. Rooting of the other clones, in both studies, was about the same at both substrate temperatures. (C) 1998 Elsevier Science B.V. Al rights reserved.
