Effects of Nodal Position and Source of Explants on in Vitro Culture Initiation of Kiwifruit ( Actinidia spp.)

In vitro techniques help speed propagation and preservation of elite cultivars. To improve the efficiency of in vitro culture initiation of kiwifruit plants, we have investigated the influence of the nodal explant position on the donor plant and explant source. Field‐grown and indoor‐grown cane materials from Actinidia chinensis var. deliciosa ‘Hayward’ and A. chinensis var. chinensis ‘Zesy002’ were used. A total of 1106 nodal explants were used in this study. Explants proximal to the apical shoot bud were more likely to result in successful culture initiation than those from distal positions. The effect of lateral shoot position along the cane on culture initiation was generally smaller than effects relating to nodal position on the lateral shoots, the source of the nodal explants (indoor dormant cane vs. outdoor actively growing cane) and cultivar. Plant material sprouted indoors from dormant cane cuttings showed less microbial growth than explants obtained from field‐grown material in active growth. This study reveals that the success of in vitro culture initiation declined with increasing distance of explants from the lateral shoot apical bud. These results may be of use for in vitro culture initiation of other species in the genus Actinida and other clonal woody plants.