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  • Author or Editor: James W. Olmstead x
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Three southern highbush blueberry cultivars (Vaccinium corymbosum hybrids) were mechanically harvested (MH) or hand-harvested (HH) and commercially packed before storage for 14 days at 1 °C in two successive years. MH fruit were softer, had lower ratings for overall appearance, and lost up to 20% more fresh weight than HH fruit after 14 days storage. MH ‘Meadowlark’ had fewer soft fruit (<35%) during storage than either ‘Sweetcrisp’ or ‘Farthing’; however, the latter two cultivars had lower incidences of shrivel and weight loss. Fruit in the 2010 season were more susceptible to bruising than those from the 2009 season; however, soluble solids content (SSC), total titratable acidity (TTA), and ascorbic acid concentration remained constant during storage and between seasons. ‘Meadowlark’ had the highest sugar to acid ratio (25.0). Successful implementation of MH of southern highbush blueberries for fresh market will only be commercially feasible if harvest impacts are further reduced.

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‘Flicker’ is a southern highbush blueberry (SHB, Vaccinium corymbosum) cultivar frequently selected by growers in Central and South Florida. In 2014, several growers in Central Florida experienced issues with anthracnose stem lesions and twig dieback on ‘Flicker’, resulting in a reduction in new plantings and the removal of many existing plantings. The objective of this study was to determine the level of anthracnose susceptibility of certain commercially available SHB cultivars, which information can be used to limit further use of susceptible cultivars in the University of Florida blueberry breeding program. The screening was performed using a spray inoculation of a virulent Colletotrichum gloeosporioides isolate onto whole V. corymbosum plants, followed by measurement of incidence and severity of disease over time. In repeated experiments, ‘Flicker’ and two other cultivars had a significantly higher mean number of lesions and area under the disease progress curve (AUDPC) than any other tested cultivar, and in both experiments, the observed lesions were similar in many respects to those previously reported on northern highbush blueberry (also V. corymbosum). Although the results of these experiments may ultimately indicate that Flicker has a unique genetic susceptibility to this form of anthracnose among SHB cultivars commercially grown in Florida, screening of additional cultivars must be performed for confirmation.

Open Access

Vaccinium arboreum Marsh is a wild species adapted to high pH (above 6.0) and low organic matter soils (below 2.0%). The use of V. arboreum rootstocks may be a viable option to increase soil adaptation of southern highbush blueberry (SHB) (Vaccinium corymbosum interspecific hybrid) under marginal soil conditions. The objective of this research was to evaluate the vegetative and reproductive traits of ‘Farthing’ and ‘Meadowlark’ SHB own-rooted or grafted onto V. arboreum and grown in pine bark–amended or nonamended soil. The study was conducted from 2012 through 2014 at a research center in Citra, FL, and a grower’s farm in Archer, FL. Vaccinium arboreum rootstock generally induced the same effects in both cultivars. Grafted plants in both soil treatments had reduced canopy growth in the first year after field planting compared with own-rooted plants in amended soil. However, canopy volume of grafted plants was greater than own-rooted plants in nonamended soil and similar to own-rooted plants in amended soil 2 years after field planting for ‘Meadowlark’ and 3 years after planting for ‘Farthing’. Fruit yield was lower in grafted plants compared with own-rooted plants in the first fruiting year (2 years after field planting). By the second fruiting year, yields of grafted plants were similar to or greater than yields of own-rooted plants when grown in nonamended soil, whereas in amended soil, yields of grafted plants were similar to yields of own-rooted plants. Grafted plants had greater mean berry weight, but lower berry firmness; however, the firmness values were still considered acceptable (greater than 160 g⋅mm−1). Internal fruit quality [total soluble solids (TSS) and total titratable acidity (TTA)] was not consistently affected by the rootstock or soil treatments. These results suggest that grafting SHB onto V. arboreum does not increase yield in the establishment years compared with own-rooted SHB when grown in amended soils, but may have the ability to increase yield with no negative effects on fruit quality when grown in nonamended soils.

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Blueberry (Vaccinium spp.) production is increasing worldwide, particularly in subtropical growing regions, but information on timing and extent of inflorescence bud development during summer and fall and effects on bloom the next season are limited. The objectives of this study were to determine time of inflorescence bud initiation, describe internal inflorescence bud development, and determine the relationship between internal inflorescence bud development and bloom period the next spring in two southern highbush blueberry [SHB (Vaccinium corymbosum interspecific hybrids)] cultivars. ‘Emerald’ and ‘Jewel’ SHB buds were collected beginning in late summer until shoot growth cessation in late fall for dissection and identification of organ development. Inflorescence bud frequency and number, vegetative and inflorescence bud length and width throughout development, and bloom were also assessed. Inflorescence bud initiation occurred earlier in ‘Emerald’ compared with ‘Jewel’. Five stages of internal inflorescence bud development were defined throughout fall in both cultivars, ranging from a vegetative meristem to early expansion of the inflorescence bud in late fall. ‘Emerald’ inflorescence buds were larger and bloomed earlier, reflecting the earlier inflorescence bud initiation and development. Although inflorescence bud initiation occurred earlier in ‘Emerald’ compared with ‘Jewel’, the pattern of development was not different. Timing of inflorescence bud initiation influenced timing of bloom with earlier initiation resulting in earlier bloom.

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Root growth and root system architecture (RSA) are affected by edaphic and genetic factors and they can impact plant growth and farm profitability. Southern highbush blueberries [SHBs (Vaccinium corymbosum hybrids)] develop shallow, fibrous root systems, and exhibit a preference for acidic soils where water and ammonium are readily available. The amendments used to create these soil conditions negatively affect the profitability of SHB plantations. Hence, breeding for RSA traits has been suggested as an alternative to soil amendments. Vaccinium arboreum is a wild species that is used in SHB breeding. V. arboreum exhibits greater drought tolerance and broader soil pH adaptation than SHB, and—according to anecdotal evidence—it develops deep, taproot-like root systems. The present study constitutes the first in-depth study of the RSA of Vaccinium species with the intention of facilitating breeding for RSA traits. Root systems were studied in rhizotron-grown seedling families. In separate experiments, we tested the effect that growth substrate and family pedigree can have on root growth and RSA. Subsequently, a genotyping by sequence approach was used to develop single nucleotide polymorphism (SNP) markers that could be used along with the phenotyping method to investigate the heritability of RSA traits and look for marker-trait associations. We found that RSA is affected by growth substrate and family pedigree. In addition, we found that V. arboreum exhibited greater maximum root depth and a lower percentage of roots in the top 8 cm of soil than SHB, and interspecific hybrids generally exhibited intermediate phenotypes. Also, we found that RSA traits exhibit moderate to low heritability and genetic correlations among them. Finally, we found 59 marker-trait associations. Among these markers, 37 were found to be located in exons, and 16 of them were annotated based on protein homology with entries in National Center for Biotechnology Information (NCBI) GenBank. Altogether, the present study provides tools that can be used to breed for root architecture traits in SHB.

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Blueberries are a high-value fruit that has experienced extraordinary growth in consumption in the past decade. Maintaining this growing market requires an understanding of the current market and its potential for expansion. To assay the impact of 36 specific blueberry sensory and psychological traits on consumer interest, a blueberry fruit quality study was constructed using techniques that allow many features to be tested in an analysis by combining specifics from different categories that describe a product. Individual traits that most impact the likelihood of fruit purchase were identified. Sweet and intense blueberry flavor yielded the most positive purchase interest, whereas bad texture attributes such as seediness were the most detrimental to interest. It was also possible to define two interest segments within the survey population that shared similar responses to particular experimentally assayed traits. The larger segment of the sample population (61%) was most interested in the aspects of blueberry flavor, whereas the second segment of respondents (39%) was most influenced by health aspects commonly associated with blueberry fruit consumption. Both segments responded negatively to bad texture. This study suggests that breeders and producers should exploit genetic and environmental variables that contribute to improved blueberry flavor and that marketing strategies to sell blueberry cultivars of superior flavor may be appropriate.

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