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J.F. Hancock, P.W. Callow, S.L. Krebs, D.C. Ramsdell, J.R. Ballington, M.J. Lareau, J.J. Luby, G.P. Pavlis, M.P. Pritts, J.M. Smagula, and N. Vorsa

Flower bud and leaf samples collected from a wide range of native North American Vaccinium populations were tested for the presence of blueberry shoestring virus (BBSSV) using the enzyme-linked immunosorbant assay. The highest disease incidence was found in Michigan (14%), although a few positive samples also were found in Virginia, New Jersey, Maine, Ontario, and Quebec. Of seven species tested, only V. corymbosum L. and V. angustifolium Ait. were infected with BBSSV.

Open access

C. K. Chandler, A. D. Draper, G. J. Galletta, and J. C. Bouwkamp

Abstract

Adaptation to upland soils was investigated in a diallel study involving progeny of 4 blueberry (Vactinium) clones consisting of 1 highbush blueberry (V. corymbosum L.) clone and 3 interspecific hybrids. Both general and specific combining ability were significant. Seedling progenies of NJUS 11 (V. ashei × V. atrococcum) and US75 (V. darrowi × V. corymbosum) grew well on an upland soil. Although not included in the diallel crosses, NJUS 64 (V. myrsinites × V. angustifolium) progenies also grew well on upland soil.

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Chad E. Finn, Carl J. Rosen, James J. Luby, and Peter D. Ascher

Seedlings from crosses among Vaccinium corymbosum L., V. angustifolium Ait, and V. corymbosum/V. angustifolium hybrid-derivative parents, and micropropagated `Northblue', `Northsky', and `Northcountry' plants, were grown for 2 years at Becker, Minn., in low (5.0) and high (6.5) soil pH regimes. Nutrient composition expressed as a concentration and total content was determined for P, K, Ca, Mg, Fe, Mn, Zn, Cu, and B in the aboveground portion of the plant. Except for Fe, the pH regime effects on aboveground plant nutrient concentration and total content were much larger than population or population × pH regime interaction effects. Population × pH regime interactions were detected for all nutrients expressed as a concentration, except for P. Generalizations about plant performance and nutrient concentration of the plant could only be made in the context of a given pH regime. At low pH, P and Mn tissue concentrations increased and Ca, Mg, and B concentrations decreased as the percentage of lowbush ancestry increased. At high pH, K, Cu, and B concentrations decreased as the percentage of lowbush ancestry increased. Overall plant performance on the higher pH soils appeared to be positively correlated to aboveground tissue concentrations of Mn, K, and Cu. When expressed as total content, population × pH regime effects were only significant for tissue Mn. Differences in total nutrient content attributed to soil pH were primarily related to differences in plant dry weight.

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Chad E. Finn, James J. Luby, Carl J. Rosen, and Peter D. Ascher

Progenies from crosses among eight highbush (Vaccinium corymbosum L.), lowbush (V. angustifolium Ait.), and V. corymbosum/V. angustifolium hybrid-derivative parents were evaluated in vitro at low (5.0) and high (6.0) pH for vitality, height, and dry weight. Succinic acid and 2[N- morpholino]ethanesulfonic acid (Mes) effectively maintained pH in the medium and rhizosphere. The pH regime did not affect percent radicle emergence from seed or survival; however, percent seed germination was slightly lower at high pH. The parental general combining ability (GCA), reciprocal and maternal, but not the specific combining ability (SCA) variance components were significant for plant vitality, height, and dry weight. The GCA variance components were six to 26 times larger than the SCA variance components for the plant growth traits. Variation due to pH regime was significant for vitality and dry weight but not for plant height. The progenies of parents with high percent lowbush ancestry were taller at both pH levels than those with less such ancestry. Little variation was apparent for higher pH tolerance as measured by dry weight; however, the GCA effects suggested that the progenies of some parents performed better than others at high pH. Vaccinium angustifolium parents differed in the extent to which tolerance to high pH was transmitted. In vitro screening in concert with a traditional breeding program should be effective in improving blueberry tolerance to higher pH.

Open access

R.F. Korcak

Abstract

A range of soils, with or without the addition of peatmoss, and seedlings of blueberry progenies were used in an outdoor pot study to examine the adaptability of blueberries to upland soil conditions with controlled fertilizer additions and trickle irrigation. Blueberry progenies ranged from essentially pure highbush (Vaccinium corymbosum L.) to interspecific hybrids containing varying amounts of evergreen (V. darrowi Camp), lowbush (V. angustifolium Aiton), black highbush (V. atrococcum Heller), and rabbiteye (V. ashei Reade) blueberry germplasm. The soils represented the 3 physiographic regions of the eastern United States with Berryland sand used as a comparative control. Leaf analysis for N, P, K, Ca, and Mg showed significant effects of soil, but no consistent effect of peatmoss addition or fertilizer source in the 2 years of the experiment. There were significant differences among progenies. Foliar Fe, B, Al, Zn, and Cu concentrations varied independent of soil material, progeny, or fertilizer source. Leaf Mn was significantly increased from solid 10N-4P-8K fertilizer and a significant soil by progeny interaction existed. Those progenies containing some V. angustifolium tended to have increased foliar Mn levels. The reduced vigor of the blueberry progenies grown on soils other than the Berryland sand was tentatively ascribed to induced nutrient imbalances, involving Ca, Fe, and Mn, possibly being governed by soil cation exchange capacity and organic matter reactivity.

Open access

J.J. Luby and C.E. Finn

Abstract

Genetic variance components, narrow-sense heritabilities, and general combining ability (GCA) effects were estimated for plant growth habit traits from a partial diallel cross among 17 blueberry (Vactinium corymbosum L., V. angustifolium Ait., and V. corymbosum x V. angustifolium hybrids) parents. Plant height, plant diameter, and a subjective stature rating were recorded for parent and progeny plants in 1984 after 9 growing seasons at Becker, Minn. General and specific (SCA) combining ability variances were significant for all traits. GCA variance components were larger than SCA components for height and stature rating, and heritabilities (family-mean basis) were 0.68 and 0.64, respectively, indicating the relative importance of additive genetic variance for these traits. Desired stature or height in this population should be recoverable through recurrent phenotypic selection. SCA variance components were much larger than GCA components for plant diameter measures, and heritability was low. Vaccinium angustifolium parents had very negative GCA effects for plant height and stature ratings, while parents with largely V. corymbosum ancestry had positive effects. Coefficients of determination between parental phenotype and GCA effects indicated that progeny performance should be predicted by parental phenotype for stature or height but not for diameter.

Free access

Ann Marie Connor, James J. Luby, and Cindy B.S. Tong

Variation in antioxidant activity (AA), total phenolic content (TPH), and total anthocyanin content (ACY) was examined in 1998 and 1999 in fruit of 52 (49 blue-fruited and 3 pink-fruited) genotypes from a blueberry breeding population. The species ancestry included Vaccinium corymbosum L. (northern highbush blueberry), V. angustifolium Ait. (lowbush blueberry), V. constablaei Gray (mountain highbush blueberry), V. ashei Reade (rabbiteye blueberry), and V. myrtilloides Michx. (lowbush blueberry). Using a methyl linoleate oxidation assay (MeLO) on acidified methanolic extracts of the berries, a 5-fold variation was found in AA in 1998 and a 3-fold variation in 1999 among the blue-fruited genotypes. Analyses of variance (ANOVA) revealed variation among genotypes (P < 0.0001) in single and combined years, regardless of inclusion of pink-fruited selections and adjustment for berry size. While mean AA of all genotypes did not change between the 2 years, ranking of some genotypes for AA changed significantly between 1998 and 1999. Of the 10 genotypes that demonstrated the highest AA in 1998, four were among the 10 genotypes that demonstrated highest AA in 1999. Similarly, of the 15 genotypes with the highest AA, 10 were the same both years. As with AA, mean TPH of all genotypes did not change between years and ANOVA demonstrated genotypic variation regardless of adjustment for berry size/weight or exclusion of pink-fruited selections. Changes in genotype rank occurred between years. The difference in TPH between lowest- and highest-ranking blue-fruited genotypes was ≈2.6-fold in both 1998 and 1999. Seven of the 10 highest-ranking genotypes were the same both years and TPH correlated with AA (r = 0.92, P < 0.01) on a genotype mean basis for combined years. ACY correlated less well with AA (r = 0.73, P < 0.01 for combined years). When genotypes were categorized into six groups according to species ancestry, V. myrtilloides and V. constablaei × V. ashei crosses ranked highest and second highest, respectively, for AA in both years. The groups comprised of V. corymbosum genotypes, V. angustifolium genotypes, and those with both V. corymbosum and V. angustifolium in their lineage were indistinguishable from each other. Samples from some of the genotypes were analyzed for oxygen radical absorbance capacity and ferric-reducing antioxidant power, and these aqueous-based antioxidant assays correlated well with the lipid emulsion-based MeLO (all r ≥ 0.90, P < 0.01). The three antioxidant assays may be equally useful for screening in a blueberry breeding program and the choice of assay may depend on the goal of the program and the resources available.

Free access

Charles Mainland

Mechanized harvest for processing markets has become commercially accepted for blackberries (Rubus sp.), highbush (Vaccinium corymbosum), lowbush (V. angustifolium) and rabbiteye (V. ashei), blueberries, cranberries (V. macrocarpon), grapes (Vitus labruscana, V. vinifera, V. rotundifolia, V. sp.), raspberries (Rubus ideaus) and to a lesser extent for strawberries (Fragaria × ananassa). Fruit bruising during harvest and sorting often contributes to reduced “eye appeal” and keeping quality for fresh sales. Highbush and rabbiteye blueberries are successfully machine harvested for fresh markets, however, high temperature and rain will often make product quality unacceptable. Highbush blueberries grown in cool climates and rabbiteye blueberries with greater inherent resistance to bruising have most consistently given acceptable quality. Cultivar improvement and equipment that causes less bruising during harvest and sorting will be required for increased mechanization for fresh markets. Mechanical pruning of blackberries, blueberries, grapes and raspberries can reduce costs by up to 80%. The audience will be involved in discussion of advancements in mechanization techniques.

Free access

Charles Mainland

Mechanized harvest for processing markets has become commercially accepted for blackberries (Rubus sp.), highbush (Vaccinium corymbosum), lowbush (V. angustifolium) and rabbiteye (V. ashei), blueberries, cranberries (V. macrocarpon), grapes (Vitus labruscana, V. vinifera, V. rotundifolia, V. sp.), raspberries (Rubus ideaus) and to a lesser extent for strawberries (Fragaria × ananassa). Fruit bruising during harvest and sorting often contributes to reduced “eye appeal” and keeping quality for fresh sales. Highbush and rabbiteye blueberries are successfully machine harvested for fresh markets, however, high temperature and rain will often make product quality unacceptable. Highbush blueberries grown in cool climates and rabbiteye blueberries with greater inherent resistance to bruising have most consistently given acceptable quality. Cultivar improvement and equipment that causes less bruising during harvest and sorting will be required for increased mechanization for fresh markets. Mechanical pruning of blackberries, blueberries, grapes and raspberries can reduce costs by up to 80%. The audience will be involved in discussion of advancements in mechanization techniques.

Free access

Mark K. Ehlenfeldt and Robert B. Martin Jr.

Eighty-seven highbush blueberry and species-introgressed blueberry cultivars were evaluated for fruit firmness in the 1998-2000 growing seasons with a FirmTech 1 automated firmness tester. Significant differences were observed among cultivars. An average firmness of 136.1 g·mm-1 of deflection (g·mm-1 dfl) was observed across all studied cultivars, and a range of 80.4 g·mm-1 dfl (`Herbert') to 189.0 g·mm-1 dfl (`Pearl River'). Species ancestry was not consistently related to firmness; however, cultivars with higher firmness values often possessed a higher percentage of Vaccinium darrowi Camp and V. ashei Reade ancestry. Conversely, cultivars with softer than average fruit often possessed a higher percentage of lowbush (V. angustifolium Ait.) ancestry. This information may help to identify sources of breeding material for increased firmness in highbush blueberry hybrids.