The successful cultivation of blackberries in subtropical regions like Florida depends on selecting low-chill cultivars capable of withstanding high temperatures, disease pressure, and minimal chilling hours. This study evaluates the performance of 17 breeding lines alongside four commercial cultivars ('Freedom', 'Ponca', 'Horizon', and 'Osage') to determine their adaptability to Florida’s climate. The goal is to identify blackberry germplasm with the potential for high yields, good fruit quality, and post-harvest stability under these challenging conditions. Field trials were established in late June 2023 at the Citra Research Center, Central Florida, using three-month-old greenhouse-grown plants successfully transplanted into the field. Data collection focused on key production parameters, including total yield, single berry weight, and marketable fruit percentage. Fruit quality was assessed through pH, Brix, and organic acid composition (tartaric, citric, and malic acid). Subjective evaluations of firmness, flavor, and seed content were also conducted. Additionally, post-harvest performance was analyzed by monitoring decay, leakage, and red druplet reversion after seven days of cold storage at 5°C. Preliminary results indicate considerable variation among the evaluated cultivars. 'BLB', 'BLH', 'BLA', and 'Freedom' exhibited the highest yields, whereas 'BLG', 'BLP', and 'BLI' were among the lowest-yielding selections. Berry size ranged from 8.98 g in 'BLB' to 5.27 g in 'Osage'. Acidity levels varied significantly, with 'BLC' (pH 4.01) and 'BLJ' (pH 3.99) displaying the mildest flavor profiles, while 'BLP' (pH 3.60) and 'BLQ' (pH 3.62) exhibited higher acidity. Beyond fruit evaluations, plant vigor and structural characteristics were documented. Prior to last year’s harvest, primocane count and height were recorded, and this season, plants were rated based on vigor, overall health, and the proportion of green versus brown canes. Ongoing data analysis will further clarify cultivar performance in relation to plant growth and long-term productivity. This research provides valuable insights into selecting blackberry cultivars best suited for Florida’s subtropical environment. The findings will contribute to optimizing cultivar recommendations for growers looking to enhance yield, fruit quality, and marketability in sub-tropical climate production systems like Florida.
