Fruit quality parameters are typically reported by growers and researchers as an average. However, for small fruits such as blueberries, berry-to-berry variability in texture and flavor also impacts the consumer eating experience. The objective of this project was to capture how fruit quality uniformity varies by 1) cultivar, 2) berry maturity, and 3) exogenous phytohormone applications. From 2022-2023, analyses were conducted on individual blueberries from multiple studies carried out in commercial fields in Michigan. First, we compared the uniformity of berry weight, diameter, firmness, and total soluble solids in six northern highbush blueberry cultivars: “Duke,’ ‘Bluecrop,’ ‘Draper,’ ‘Calypso,’ ‘Elliott,’ and ‘Aurora.’ Second, we evaluated how changes in berry maturity due to delayed harvest and sequential harvest dates affected the uniformity of berry weight, diameter, firmness, total soluble solids, pH, total acidity, and aroma volatile concentrations in: ‘Duke,’ ‘Draper,’ ‘Calypso,’ and the uniformity of berry weight, diameter, firmness, and total soluble solids in ‘Bluecrop,’ ‘Elliott,’ and ‘Aurora,’ respectively. The implications of delayed harvest on the uniformity of consumer liking scores will also be discussed. Finally, we tested whether exogenous application of multiple phytohormones impacted the uniformity of berry weight, diameter, firmness, and total soluble solids in ‘Bluecrop,’ ‘Elliott,’ and ‘Aurora’. We conclude that “uniformity” is an important component of fruit quality in blueberry.
Plant growth regulators (PGRs) are natural or synthetically derived plant hormones that play a significant role in shaping plant growth and development. In tree fruit and table grape production, PGRs are commonly employed to address production challenges, including modulating crop load and improving fruit size, coloration, and quality. Meanwhile, their use in berry crops such as blueberry remains limited despite the prevalence of production challenges and the availability of registered PGRs for other fruit crops. This review summarizes the existing literature regarding PGR use in blueberry, as well as the current needs for research on PGRs going forward. First, considering the large increase in U.S. blueberry production over the past decade, we highlight the lack of PGRs registered and utilized in blueberry compared to other fruit crops. Second, we summarize the current literature on the utility of PGRs to mitigate challenges in blueberry production, including cold hardiness and frost protection, dormancy release, fruit size and crop load management, fruit quality improvement, post-harvest shelf-life extension. Finally, this work presents future opportunities for research involving PGRs in blueberry production. As blueberry production continues to increase in the U.S. and globally, the need to mitigate production challenges using PGRs will likely also increase.
The 'Calypso' blueberry has emerged as a popular variety widely planted in the Pacific Northwest. Its reputed storage quality and reasonable firmness suggest its suitability for mechanical harvesting in the fresh market using over-the-row machine harvesters. To explore its postharvest quality after both hand and machine harvest, we conducted a comprehensive study in a commercial, 7-year old 'Calypso' field in Oregon. Additionally, a drop test was employed to simulate machine harvesting for fresh market blueberries. Throughout a 4-week period of cold storage, fruit firmness generally remained stable, with occasional increases noted, while berry size remained consistent, indicating 'Calypso' maintains good storage quality. Examination of fruit internal bruise damage (IBD) by cutting berries along the equator revealed consistent levels of IBD throughout cold storage, elucidating why 'Calypso' enjoys a good shelf life. The drop test demonstrated 'Calypso's' resilience to damage from drops, with a similar pattern of fruit IBD development observed between drop-tested and machine-harvested fruits. This study highlights the slow rate of IBD development in 'Calypso' fruit as a crucial factor contributing to its success in machine harvesting for fresh market operations.
Cranberry growers in Massachusetts still rely primarily on heritage cultivars, such as Howes (1843) and ‘Early Black’ (1852). The research aims to increase the profitability and sustainability of the Massachusetts cranberry industry by evaluating twelve new hybrid cultivars for improved yield, fruit quality, disease resistance, and size. The research project was initiated in March 2021 with the prorogation of the new cultivars in a greenhouse. At the same time, the renovation of a 0.75-acre cranberry bog was initiated. The renovation included stripping off the top 0.25 m of the bog and replacing it with new sand. A new irrigation and drainage system was also installed. The new cultivars were planted in June 2021 at the Cranberry Station in East Wareham, Massachusetts. The new cultivars were planted in a randomized, complete block design with four replications per cultivar and buffer zones between the plots. Standard commercial cultural practices for new plantings regarding irrigation, fertilization, pest control, and canopy management were followed. Fruit was removed from the vines to allow maximum resource allocation for canopy growth in 2022, and the first fruit harvest was in 2023. Yield was measured by picking all fruit within a 0.09 m 2 quadrat. The fruit samples were then sieved through an 8-mm opening to remove undersized berries; the remaining berries represented the yield of marketable berries. Additional samples (≈500 g) were collected from each treatment replication for fruit quality analysis. Fruit color was measured using total anthocyanin content (TAcy). Regarding yield, Haines® (353 barrels/acre), Welker™ (287 barrels/acre), and Crimson King (243 barrels/acre) were the most productive, while Vassana® (112 barrels/acre) and HyRed® (117 barrels/acre) performed poorly, with the other cultivars in the mid-range. Scarlet Knight® (81 TAcy), HyRed® (65 TAcy), and Midnight 8 (58 TAcy) had the best fruit color, while Badger (16 TAcy), Granite Red (22 TAcy), Sundance (24 TAcy), and Pilgrim King (26 TAcy) had poor fruit color. The highest fruit rot incidence was observed in HyRed® (37%), Welker™ (52%), and Vassana® (63%), while Granite Red (11%), Mullica Queen® (13%), Badger (18%), and Sundance® (19%) had the lowest incidence. The fruit size measured as fruit diameter was largest in Badger (20.3 mm), Granite Red (20.3 mm), Crimson King (19.8 mm), and Haines® (19.5 mm). In conclusion, first-year harvest data showed differences in the performance of the cultivars under MA growing conditions. Additional data from multiple years are still needed to provide growers with recommendations.
