Rootstock and Scion Interactions in Newly Grafted Highbush Blueberry Plants

Three highbush blueberry cultivars ‘Draper’, 'Liberty', and 'Aurora' were grafted onto two wild Vaccinium arboreum rootstocks from Taxes and Oklahoma sources. The whip-tongue grafting was performed under greenhouse conditions in January with one-year old dormant scion wood. The average greenhouse temperature was at 180 °C with supplement lighting to provide 16 hours of more than 600 µmol·m^-²·s^-1 photosynthetically active radiation. Grafting take rate was over 90% regardless cultivars and rootstock types. Ten grafted plants from each cultivar and rootstock combination were chosen as single plant replicate and arranged in a complete randomized design in the greenhouse. Misting irrigation was provided to maintain a relative humidly of 80%. No rootstock and scion interactions were observed during a 4-month growing period.  While there were no differences in shoot numbers produced between two rootstock types, later cultivar ‘Aurora’ had 35% more shoot numbers than early cultivar ‘Draper’. Grafted plants with Taxes rootstock produced 30% more total shoot growth than those with Oklahoma rootstock during the first month of growth. This rootstock differences in total shoot growth dissipated with the time of growth period. Total shoot growth among three highbush cultivars was not different for all weekly measurements. These grafted plants will be transplanted to field plots for further studies.