|Perkins Veazie, Penelope|
Submitted to: Journal of Horticultural Science and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2003
Publication Date: 1/1/2004
Citation: Leskovar, D., Bang, H., Crosby, K., Maness, N., Franco, A., Perkins Veazie, P.M. 2004. Lycopene, carbohydrates, ascorbic acid and yield components of diploid and triploid watermelon cultivars are affected by limited irrigation. Journal of Horticultural Science and Biotechnology. 79:75-81.
Interpretive Summary: Vegetable production in the southwestern US is often strictly regulated on water use, but effects of limited irrigation on crop production and quality are largely unknown. Watermelon production under limited irrigation was studied to determine effects on watermelon yield and quality. Irrigation at full, half, and 3/4 evapotranspiration rates (ET) was applied to seeded and seedless watermelonsusing subsurface drip irrigation. Lycopene, sugar and vitamin C content did not decrease with limited irrigation. Yields and flesh firmness were higher for seedless than for seeded types. Results indicate that irrigation can be limited to 3/4 of full ET without adverse effects on quality.
Technical Abstract: Many vegetable production regions in southwestern US are strictly regulated on water use. In addition, demand for high quality and nutritious vegetables has increased. This study was performed to explore the effects of limited irrigation on yield, fruit quality, lycopene content, vitamin C and sugar composition of red-fleshed diploid and triploid watermelon (Citrullus lanatus (Thunb) Matsum & Nakai) cultivars. Irrigation treatments were 1.0, 0.75 and 0.5 ET rates. Cultivars used were Summer Flavor 710, RWM 8036, Allsweet, Sugarlee, and SWD 7302 (diploids) and Summer Sweet 5244, SWT 8706, Sugar Time, and Tri-X-Sunrise (triploids). Total water applied through a subsurface drip system was 395, 298 and 173 mm, for the 1.0, 0.75 and 0.50 ET, respectively. Total yields were highest at 1.0 ET (53.9 MT ha-1) compared to 0.5 ET (26.8 MT ha-1). Triploids had a 34% higher total yield and fewer culls (2%) compared to diploid cultivars (25%). Highest yields were obtained for Tri-X-Sunrise, SWT 8706, and SWD 7302. Highest soluble solid content was measured for Sugar Time (13.4%) and was significantly higher than other cultivars (range 9.7-11.0 %). Triploid cultivars had a more firm flesh compared to diploids (12.0 vs. 9.9 N). Lycopene content increased slightly with maturity (55.8 to 60.2 ug g-1 fw) and was significantly higher at 0.75 ET than 1.0 ET. Lycopene content averaged over all treatments was 60-66 ug g-1 fw for triploids and 45 to 80 ug g-1 fw for diploid fruits. There was a genetic and environmental variability for lycopene content and sugar composition, primarily fructose, among diploids and triploids. Overall, lycopene, total sugar and vitamin C content did not decrease with limited irrigation.