Tissue culture production of hazelnut – disinfestation and impact of agar content

Abstract

Australian hazelnuts are a new and emerging industry with the potential annual value in Tasmania alone estimated to be in the order of $ 10-15 million. Currently tree propagation is a slow and inefficient process with suckers collected from mature trees and grown on in nurseries. This parent material may harbour diseases and pests and surviving progeny may have inconsistent growth rates, undesirable suckering and non-uniform growth habits, making orchard establishment challenging. The development of tissue culture technologies for hazels has been pioneered in Oregon, USA, resulting in new cultivars and improved planting stock underpinning successful industry establishment in the USA. There has been little success with tissue culture production of local cultivars in Australia. This project examined strategies to optimise the transfer of glasshouse and field grown cuttings (explants) into axenic tissue culture, by testing different disinfestation treatments with sodium hypochlorite (NaOCl). Further, once in tissue culture, we tested the impact of varying agar content in media on key growth parameters. Outcomes indicated fungal and bacterial contamination from field-sourced explants was greater than those from glasshousesourced and that a greater NaOCl concentration (2.1% compared to 1.05%) was required to obtain axenic tissue cultures. Also, low agar content (0.2-0.4%) in tissue culture media produced improved hazel explant growth with greater shoot fresh weights and node numbers than with high agar content. These findings may help underpin the development of micro-propagation as a useful source of quality planting material for the hazelnut industry in Australia.