What Microclimate Variables Are Key Drivers for Strawberry Varieties Produced in Tunnel Systems?.

The United States is the world’s largest strawberry (Fragaria x ananassa Duchesne ex Rozier) grower with the majority of production centered in California. Berry cultivation, however, is still wide-spread throughout the country due to the crop’s high value, large consumer demand, and short shelf-life. With the exception of Florida, production in the east-coast is largely confined to a three to five week period with a single cultivar. As a result, the strawberry market in this region is vulnerable to pests and diseases and is insufficient to support local demand in years of low berry productivity from the west coast. The adoption of repeat-fruiting cultivars may address these issues in the Mid-Atlantic region and bolster local rural economies, but production systems better suited to meet the cultural needs of these varieties need to be evaluated. Results from recent research using low-plastic tunnels over mulched beds demonstrated it was possible to achieve high yields from March through November in Maryland with these genotypes. However, the relationship between yields and micro-climate conditions needs to be quantitatively evaluated in order to improve design and management of these systems. In this case, eight day-neutral strawberry genotypes were grown in low-tunnel (closed treatment) and no-tunnel (open control) systems for two years at the USDA-ARS facilities in Beltsville, Maryland. Berries were periodically harvested (at least once weekly) throughout the growing seasons. Microclimate data including maximum and minimum air, crown, and soil temperatures, leaf wetness, soil moisture content, photosynthetically active and shortwave solar radiation, and relative humidity were recorded as 15-minute averages. This presentation focuses on the statistical relationships between these characteristics and berry yield for the two tunnel systems, evaluating differences due to genotype, and assessing the use of a growing-degree-day approach to estimate expected yields.