Evaluating the Performance of Southern Highbush Blueberry Cultivars Grown in Conventional and Alternative Production Systems

Abstract

The blueberry is the most valued berry fruit in the United States. The rising demand for blueberries can be accomplished by increased production areas in warmer climates. The enhanced adaptability of southern highbush blueberry (SHB) played a significant role in this expansion. However, the production of SHB in open fields is limited by climatic and soil-related conditions such as insufficient chilling accumulation, spring frost injury, and site-specific soil requirements. To address these challenges, alternative production systems (high tunnels and containerized) have been introduced, which can potentially alleviate these problems. This study evaluated the physiological and phenological responses of three SHB cultivars -‘Meadowlark’, ‘Victoria’, and ‘Jewel’ grown under three production systems [high tunnel (HT), open field (OF) and open-field containerized (OFC)] at Auburn University research sites (Plant Science Research Center, Auburn, and E.V. Smith Research Station, Tallassee) during 2024-2025. Physiological parameters, including stomatal conductance, stomatal density, stomatal area, and chlorophyll content, along with yield and fruit quality traits, were measured, and phenological development was recorded from bud swell to harvest. Accumulated chilling hours (temperature between 0-7°C) and growing degree days (GDD, base temperature of 7°C) were calculated, and data were analyzed using PROC GLIMMIX and ordinal logistic regression in SAS. Across both years, microclimate conditions differed among production systems. The OF and OFC systems generally promoted higher stomatal conductance and stomatal density, whereas the HT provided a more stable environment that enhanced yield and fruit quality. ‘Victoria’ consistently produced higher yields with larger berry size, particularly under HT, while ‘Meadowlark’ exhibited greater fruit firmness and earlier phenological progression. ‘Victoria’ accumulated the highest number of chill hours (≈ 462-465 h), followed by ‘Jewel’ (≈ 251-256 h), and ‘Meadowlark’ (≈ 195-197 h) to break endodormancy across the three production systems. Among the production systems tested, total GDDs from dormancy to harvest ranged from ≈ 810-899 for ‘Meadowlark’, ≈ 887-1014 for ‘Jewel’, and ≈ 974-978 for ‘Victoria’. HT advanced phenological stages and harvest timing, whereas the OF and the OFC production systems delayed progression under cooler conditions. Overall, adopting alternative production systems such as HT can mitigate climatic stress, improve yield and fruit quality, and support sustainable SHB production under Alabama’s environmental conditions.