2013 ASHS Annual Conference

In 2010, Missouri ranked 9th nationally in watermelon production.  There were 3,200 acres of watermelons harvested with a total value of $857,600. The seedless watermelon industry demands high-yielding varieties that demonstrate high °Brix values. The objective of this trial was to evaluate the most recent seedless watermelon varieties and update variety recommendations. Twenty-four triploid watermelon varieties were chosen for this study, but due to limited seed availability not all varieties were planted in the three testing locations. Seeds were started in a greenhouse three weeks before transplanting in early May for the southwest and southeast regions of Missouri and late May for central Missouri. Seedlings were planted into raised beds covered with black plastic mulch at Lincoln University’s Carver Farm in Jefferson City (central Missouri), the Southwest Research and Education Center of University of Missouri at Mount Vernon (southwest Missouri), and a private farm near Malden (southeast Missouri). Vines of the diploid varieties ‘Accomplice’, ‘Gladiator’ and ‘Estrella’ were used as pollenizers. The experiment was conducted as a completely randomized design at each site, with four replications per cultivar and four plants per replication. Harvests were conducted as fruit ripened at the Mt. Vernon site, July 3–12, 2012. Single-day harvests were conducted on August 6, 2012, at the Jefferson City site, and on July 17, 2012, at the Malden site. Data collection consisted of yield and number of fruit/vine at all three sites. One fully ripe medium-sized fruit from each replication plot was selected to determine fruit characteristics including fruit diameter, fruit length, rind width and soluble solids concentration. Marketable yield ranged from 3.3 to 9.9 tons/acre, lower than typical yields due to extended periods of extreme heat and drought. Fruit weights were low in the southwest region (7.5–12.4 lbs.) where it was noted that plants seemed to lack vigor compared to previous years, whereas average fruit weights in the central region ranged from 8-15.5 lbs. The red-fleshed varieties ‘Sweet Delight’, ‘Palomar’, ‘Millionaire’, and ‘Crispy Red’ as well as the yellow-fleshed variety ‘Buttercup’ performed well in terms of yield during the challenging growing season. When comparing fruit characteristics among sites, few differences were detected except that °Brix was higher overall at the central Missouri site with a mean of 12. These varieties should be tested again to determine if performance improves during a typical Missouri growing season.