Branching in Jojoba (Simmondsia chinensis): Natural variation and effects of plant growth regulators and pruning

Abstract

In jojoba, flower buds are typically produced at every other node on new growth near branch tips. An increase in the number of branch tips (branching frequency) could possibly increase flower bud and fruit production. Studies were conducted to determine the effects of three concentrations of Benzyladenine (BA), Gibberellin4+7 (GA), and Promalin (a mixture of BA and GA) on branching and flower production of three jojoba clones. Treatments involving pinching and untreated control plants were also included. The growth regulators had a significant effect on both branching and flower bud production, and clones differed in their response. For the most responsive clone, the most effective treatments (100 ppm GA and 100 ppm Promalin) resulted in 133% and 110% increase in flower buds after 17 months, respectively. The increase in flower buds was associated with an increase in the number of growing tips and node production. Similar responses were observed in both greenhouse and field experiments. The results of these studies indicate that growth regulators can be used to significantly increase flower bud production on jojoba.