Vaccinium arboreum: A Rootstock for Southern Highbush Blueberry?

Monday, July 22, 2013
Desert Ballroom: Salons 7-8 (Desert Springs J.W Marriott Resort )
Bruno Casamali , University of Florida, Gainesville, FL
Rebecca L. Darnell , University of Florida, Gainesville, FL
Jeffrey G. Williamson , Horticultural Sciences Department, University of Florida, Gainesville, FL
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.