Southern highbush blueberry (SHB) cultivars are susceptible to spring frost damage, which can significantly reduce both yield and fruit quality. To mitigate the impacts of frost, alternative production systems, such as high tunnels, have been explored for their potential to improve SHB production. This study evaluated the performance of three SHB cultivars (‘Meadowlark’, ‘Victoria’, and ‘Jewel’) under high tunnels (HTs) and open fields (OFs). Stomatal conductance (SC), stomatal density (SD), stomatal area (SA), fruit quality, and quantity were measured, and weather variables were recorded. Data were analyzed using Proc Glimmix and Tukey’s HSD test was applied for mean separation (p ≤ 0.05). SC varied significantly by cultivars (p < 0.001) and production systems (p < 0.001), with higher SC observed in OFs. ‘Meadowlark’ exhibited the highest SC followed by ‘Jewel’ and ‘Victoria’. SD and SA were significantly influenced by the production systems and leaf stage, with all three leaf stages in OFs showing the highest SD and SA compared to HTs. SD was greater in younger leaves and decreased with leaf age, whereas SA was higher in mature and older leaves. Cultivars also affected SD and SA, with ‘Meadowlark’ showing the highest SD and SA, followed by ‘Victoria’ and ‘Jewel’. The yield was higher in HTs across all cultivars, with ‘Victoria’ producing the highest yield followed by ‘Jewel’ and ‘Meadowlark’. Single berry weight was significantly affected by both cultivars and production systems (p = 0.0004), with ‘Meadowlark’ and ‘Victoria’ producing larger berries in HTs, while ‘Jewel’ had the smallest fruit in both systems. Brix levels were cultivar dependent (p = 0.0005), with ‘Meadowlark’ exhibiting the highest values. Firmness was influenced by cultivars (p < 0.001) and among three cultivars, ‘Meadowlark’ had the highest firmness, while ‘Jewel’ had the lowest. In conclusion, SHB cultivars in HTs likely optimized their water use efficiency by reducing SC, SD, and SA. ‘Victoria’ demonstrated superior yield performance, while Brix value and firmness were higher in ‘Meadowlark’, resulting in better fruit quality. Additionally, HTs enhance total yield, berry weight, Brix, and firmness in SHB cultivars. Overall, this comparison highlights system-specific effects on cultivar performance, emphasizing the practices for southern highbush blueberry production.
