Impact of Reduced Irrigation Rates on Fruit Yield and Quality in Seedless Watermelon

Excessive irrigation in watermelon [Citrulus lanatus (Thunb.)] in many vegetable producing areas of the world is frequent due to inadequate irrigation scheduling, resulting in water waste and nutrient leaching. The objective of the study was to evaluate the effects of irrigation rates on soil moisture content, incidence of Phytophthora blight, and fruit yield and quality in watermelon. The experimental design consisted of a randomized complete block with five treatments (irrigation rates (33, 67, 100, 133, and 167% the rate of crop evapotranspiration)) and four replications. We used a seedless watermelon cultivar ('Tri-x 313' as female, and 'Ace' as the pollenizer) that is commonly grown in the southeast US. The experiment was conducted in Tifton, Georgia (sandy loam soil) and Camilla, Georgia (loamy sand soil) in the spring of 2009. The mean volumetric soil moisture content at a soil depth of 10 cm increased with the irrigation rate. The average soil moisture content over the season for the irrigation rates were: 8.5% (33% ET), 10.7% (67% ET), 9.3% (100% ET), 13.1% (133% ET), and 13.6% (167% ET). Fruit yields and average fruit weight were not significantly affected by irrigation rate; however, they tended to be lowest at the lowest irrigation rate (33% ET). Fruit yield and quality of watermelon plants irrigated with 67% ET were similar to those of plants irrigated at higher irrigation rates. The concentration of fruit soluble solids slightly decreased with increasing rates of irrigation. In conclusion, the results suggest that there is potential to reduce the current rates of watermelon irrigation and thus increase the water use efficiency without significantly affecting fruit marketable yields and quality.