A Multi-Disciplinary Approach to Sustainability and Profitability of U.S. Blueberry Production Using the Tree-Like Species Vaccinium Arboreum

Sustainability of the U.S. blueberry industry is constrained by high production costs in many locations, including extensive soil inputs and the need to hand harvest fresh-market berries. A critical need exists to reduce costs and increase efficiency of blueberry production, enabling growers to remain competitive and profitable. V. arboreum, a wild blueberry species, grows well on non-amended soils, and has a tree-like growth habit. Incorporating these traits into highbush blueberry would alleviate soil constraints and facilitate mechanical harvesting. Our objective is to utilize desirable traits from V. arboreum in blueberry production, through use as a roostock or by hybridization with V. corymbosum (highbush blueberry).  Using V. arboreum to produce hybrids or grafted plants that yield high-quality berries that are better suited to mechanical harvest and less dependent on soil inputs than conventional blueberry cultivars/systems would decrease production costs and increase sustainability. Both hybrids and grafted plants will be evaluated for soil adaptation, mechanical harvest potential, and fruit quality/yield. Identification of new tetraploid F1 hybrids between V. corymbosum and V. arboreum tetraploid plants (produced using colchicine) is ongoing; to date we have screened more than 50 hybrids for pollen fertility and have backcrossed 20 of the most vigorous and fertile to highbush cultivars.  From these backcrosses, we obtained 4,000 seedlings, representing three different V. arboreum lineages and ten different highbush cultivars of varying chill requirement.  These will go into field evaluation trials in February 2011 at Florida and Alabama sites. In conjunction with breeding efforts, differences in gene expression in roots of V. arboreum and V. corymbosum clones grown under different pH conditions will be evaluated, and a linkage map for QTL and candidate gene analysis will be developed from a backcross V. corymbosum x V. arboreum population. Differences in root physiology between the two species, and among the F1 and BC populations, will also be determined in response to pH and other rhizosphere conditions. For grafted combinations, we are currently growing V. arboreum seedlings for use as rootstocks for southern and northern highbush cultivars. Research and grower demonstration plantings of grafted vs. own-rooted highbush blueberry will occur in Florida, Alabama, Oregon, and California. Additional studies will be done in concert with the above to evaluate diverse populations of V. arboreum seedlings for use as highbush rootstocks and to develop methods to asexually propagate desirable rootstocks.