Physiological Comparison of Three Southern Highbush Blueberry Cultivars Under High Tunnel and Open Field Conditions

Abstract

Recent studies have shown that high tunnel production of blueberries generates higher biomass accumulation due to the microclimates created compared to open field production. This study aimed to evaluate the physiological responses and the effect on the growth and development of three southern highbush cultivars under high tunnel conditions and compare it to an open field production system. A total of 180 southern highbush blueberry plants of ‘Farthing’, ‘Indigo Crisp’, and ‘Legacy’ cultivars were planted in March 2022, under high tunnel and open field conditions. Ambient temperature, soil temperature, relative humidity, and daily light integrals were monitored in both conditions. Biomass accumulation, leaf area, and height were measured throughout the season, as well as physiological parameters through gas exchange analysis. The results showed that the microclimate created under the high tunnel affected plants differently across cultivars. Biomass accumulation for ‘Legacy’ was 16.4% higher in the open field compared to the high tunnel but biomass was not affected by condition for either ‘Farthing’ or ‘Indigo Crisp’. However, all cultivars under the high tunnel showed expedited phenological progression during blooming. Diurnal measurements showed that plants under the high tunnel had a higher photosynthetic rate compared to outside conditions. Biomass accumulation coincides with the physiological measurements since ‘Farthing’ and ‘Indigo Crisp’ showed no differences in photosynthetic rate between conditions, and ‘Legacy’ had higher carbon assimilation outside of the high tunnel compared to plants under high tunnel conditions. This study provided insight into the importance of cultivar selection in high tunnel production. It also allowed a further understanding of the physiological responses of healthy plant growth and development under an alternative system of production.