ARS | Publication request: Rootstock of interspecific squash hybrids (Cucurbita maxima x Cucurbita moschata) increases lycopene content of watermelon

Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2008
Publication Date: July 1, 2008
Citation: Perkins Veazie, P.M., Olson, S.M., Hassell, R.L., Schultheis, J.R., Miller, G., Kelly, W.T. 2008. Rootstock of interspecific squash hybrids (Cucurbita maxima x Cucurbita moschata) increases lycopene content of watermelon [abstract]. HortScience. 43(4):1199-1200.

Technical Abstract: The watermelon industry in the U.S. is facing increased soil-borne disease pressure and the loss of the soil fumigant methyl bromide. To combat this, grafting of scions with disease-resistant rootstocks of cucurbit species has garnered widespread interest. Both scion and rootstock can affect plant productivity and fruit quality, as determined by fruit size, fruit number, shape, flavor, sweetness, and flesh color. However, little has been reported on grafting effects on carotenoid content of watermelon. Four locations in the Eastern U.S. (Florida, North Carolina, South Carolina, and Georgia) grew the same seedless scion (Matrix or Liberty, with rootstock combinations of interspecific squash hybrids (C. maxima x C. moschata), bottle gourd (Lagenaria siceraria), or on their own rootstock (C. lanatus) in 2007. Tissue was sampled from the center (heart) area of the fruit and analyzed for lycopene, pH, and soluble solids content. In each location, lycopene content was higher in fruit from interspecific hybrids and lowest from fruit that were grafted on their own rootstocks. Lycopene values ranged from 66 to 73 mg/kg in fruit of scions grafted to 'Chilsung Shintosa,' 'Shintosa Camel,' 'Strong Tosa,' or 'WR 15006,' compared to self-grafted fruit. Those fruit from the bottle gourd rootstocks were 10% lower in lycopene than fruit from the interspecific hybrids. Fruit pH and soluble solids content did not show strong differences among scion/rootstock combinations, but unripe and overripe fruit could be discriminated from ripe fruit based on pH (4.9-5.2 unripe; >6.4 overrripe). The consistently higher lycopene content from one type of rootstock may be from enhanced carbohydrate accumulation with partinioning into carotenoid synthesis.