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Journal of the American Pomological Society
(J Am Pom Soc)

American Pomological Society

Volume 73 Number 4 Article 6 Pages: 254-268
Year 2019 Month 10
Title: Frequency of Harvest affects Berry Weight, Firmness, Titratable Acidity, and Percent Soluble Solids of Highbush Blueberry Cultivars in Oregon
Author: Bernadine C. Strik
Citation
Abstract:
The impact of picking frequency was studied over 2 years in seven cultivars (‘Aurora’, ‘Bluecrop’, ‘Draper’, ‘Duke’, ‘Liberty’, ‘Legacy’, and ‘Ozarkblue’) of highbush blueberry (Vaccinium sp. L.) in Aurora, Ore. In 2011, fruit were picked every 2–3 d, 4–5 d, or 7d. Picking frequency was adjusted from 2011 to 2012 to be more typical of the range in commercial practice. In 2012, picking frequency was every 4 d (“high”; when fruit was first fully blue), 8 d (“medium”), and 12 d (“low”). When fruit were picked every 7–8 d, there was no effect of year on yield, berry weight, firmness, percent soluble solids (TSS), titratable acidity (TA), or sugar to acid ratio (TSS:TA). Berry weight declined consistently over the harvest season for ‘Aurora’ and ‘Ozarkblue’, was smaller on the early harvests with high frequency picking for ‘Draper’, ‘Legacy’, and ‘Liberty’, and was quite stable over the season for ‘Bluecrop’ and ‘Duke’. ‘Bluecrop’, ‘Draper’, and ‘Duke’ berries were less firm on the last harvest of the season for medium and low picking frequency, whereas there were fewer effects of harvest date within treatment for the other cultivars. In general, TSS increased and TA decreased during the harvest season for each cultivar leading to an increase in TSS:TA. Picking frequency had no effect on yield, but picking every 12 d instead of 4 d increased average berry weight by 5%, 14%, 20%, 25%, and 29% in ‘Aurora’, ‘Liberty’, ‘Legacy’, ‘Duke’, and ‘Draper’, respectively. Picking every 12 d decreased average fruit firmness 5–8 % for ‘Draper’, ‘Aurora’, ‘Bluecrop’, and ‘Liberty’ and 12% for ‘Duke’ compared to picking every 4 d, but had no effect for ‘Legacy’ and ‘Ozarkblue’. While there was no effect of picking frequency on TSS of ‘Duke’, in all of the other cultivars, harvesting every 12 d increased TSS compared to harvesting every 4 d. Berry TA was much greater and TSS:TA much lower with a high picking frequency than either medium or low frequency in all cultivars. With a high picking frequency, focused on harvesting berries when first blue, the fruit were not fully ripe and thus while they were firm they had a relatively low berry weight and TSS, high TA, and low TSS:TA. Reducing hand-picking frequency from every 4 to 12 d reduced labor costs 64% from fewer passes through the field and likely improved picking efficiency from larger berries. The results confirm that harvest interval may be extended in this region to reduce harvest costs with little to no negative impact on fruit quality variables and some positive impact on TSS:TA and berry weight.

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