Effects of Harvest Time on the Quality of Highland Ever-Bearing Strawberries ( Fragaria  ×  ananassa Duch.) in Summer

Ever-bearing strawberries (Fragaria × ananassa Duch.) produce fruit year-round, unlike June-bearing cultivars that primarily fruit in winter and spring. In South Korea, ever-bearing cultivars are increasingly used for high-altitude summer cultivation, with transplantation in March/April and harvest from June to November. In this study, we investigated the effects of harvest time on growth, yield, fruit quality, and antioxidant properties of three ever-bearing cultivars grown in high-altitude regions during summer (July to October). In July, vigorous vegetative growth was observed, with the highest marketable fruit rate (80.5%) and average fruit weight (11.9 g). The greatest number of marketable fruits (9.6 fruits/plant) and highest total marketable yield (7,369 kg·10a−1) were noted in August. The productivity declined in September, whereas functional components such as titratable acidity, total anthocyanin content, and radical scavenging activity reached their maximum levels. By October, fruit quality parameters improved significantly: total soluble solids increased to 10.8 °Brix, whereas firmness and sugar-to-acid ratio reached their peak values. Conversely, plant height (28.5 cm) and leaf length (7.4 cm) decreased due to the onset of dormancy. These findings provide a foundation for developing climate-resilient cultivation systems that ensure stable, high-value strawberry production in response to increasing environmental variability.