Vaccinium arboreum: A Rootstock for Southern Highbush Blueberry?

Commercial blueberry production typically requires soil amendments to increase organic matter and decrease pH, increasing production costs. Further, most fresh market blueberries are hand-harvested, since the multi-caned architecture makes mechanical harvesting difficult. Hand harvesting is costly and labor intensive, and the supply of labor is likely to decrease in the future. V. arboreum is a wild blueberry species native to the southeastern United States that tolerates soils with pH up to ~6.5 and low organic matter, and exhibits a tree-like growth habit with a single trunk. These characteristics could potentially be exploited in commercial blueberry production by using V. arboreum as a rootstock to increase soil adaptation and mechanical harvest ability. The objective of this study is to evaluate canopy growth, bloom period and fruit yield in grafted vs. own-rooted southern highbush blueberry under two soil management systems—non-amended soil and pine-bark amended soil. Two cultivars were evaluated in two experiments at different sites. At both sites, treatments were arranged in a 4 x 2 factorial (“genotype” x soil treatment), with “genotypes” comprising 1) own-rooted ‘Farthing’; 2) ‘Farthing’ grafted onto V. arboreum; 3) own-rooted ‘Meadowlark’; and 4) ‘Meadowlark’ grafted onto V. arboreum. Fruit yield the first season after planting was not different for ‘Farthing’, however, own-rooted ‘Meadowlark’ plants had greater fruit yield than ‘Meadowlark’ grafted plants, averaging 148.7 g and 78.5 g per plant, respectively. In both years and for both cultivars, own-rooted plants grown in pine-bark amended soil had the greatest canopy volume. ‘Farthing’ grafted plants, regardless of the soil system, had the smallest canopy volume. ‘Meadowlark’ grafted plants in both soil systems, and own-rooted plants in non-amended soil had similar canopy volumes, which were smaller than own-rooted plants in pine-bark. In 2012, bloom period was shorter for grafted ‘Farthing’ vs. own-rooted ‘Farthing’, but not different for ‘Meadowlark’. In 2013, ‘Farthing’ and ‘Meadowlark’ grafted plants had shorter bloom periods than own-rooted plants. Soil management systems also affected bloom period. ‘Meadowlark’ plants on non-amended soils had a shorter bloom period than plants on amended soils, while this effect was not observed for ‘Farthing’. Vegetative growth on own-rooted plants was always greater in amended compared with non-amended soils. However, vegetative growth of grafted plants was not affected by soil management systems.