Determination of Sugars in Three Varieties of Watermelons in Kentucky

Watermelon is a popular summer fruit marketed locally and universally with production scattered throughout the state of Kentucky. Watermelon, Citrullus lanatus L. varietal selection continues to be a primary consideration for Kentucky farmers so they can make decisions to suit their needs in yield, disease resistance, and buyers’ needs for fruit composition, quality, and appearance. A field experiment was established at Kentucky State University Research Farm to grow watermelons under seven soil management practices (chicken manure, sewage sludge, cow manure, biochar, vermicompost, chitin, and control treatment) and investigate the impact of soil management practices on watermelons yield and the sugar content of three varieties of watermelon fruits (Black Diamond, Dark Belle, and Mama’s Girl). At harvest, samples of watermelon fruit tissues were collected at random and homogenized with 80% ethanol to extract soluble sugars. Homogenates were filtered and a one mL sample was determined calorimetrically using a pure glucose standard curve. Results indicated that none of the soil amendments impacted the concentration of sugars in watermelons. However, regardless of the soil amendments used, the variety Mama’s Girl was superior in increasing the concentration of sugars (360 mg 100 g-1 fresh tissue) compared to the Dark Belle and Black Diamond varieties (321 and 315 mg 100 g-1 fresh tissue, respectively).