Angela R. Davis and Wayne W. Fish
Wes Watkins Agricultural Research Laboratory, USDA-ARS, P.O. Box 159, Lane, OK 74555
Amnon Levi
United States Vegetable Laboratory, USDA-ARS, 2700 Savannah highway, Charleston, SC 29414
Stephen King
Department of Horticultural Sciences, Texas A & M University, College Station, TX 77843
Todd Wehner
Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695
Penelope Perkins-Veazie
Plants for Human Health Institute, North Carolina State University, Kannapolis, NC 28083
Producers of fresh fruits and vegetables face increasing production costs and more intense international market competition. Maximizing marketability by offering high quality produce that is also highly nutritious provides new market niches for crops such as watermelons [Citrullus lanatus (Thunb.) Matsum. and Nakai], but germplasm will have to be identified that has enhanced levels of nutrients. Surprisingly, there is little information on how genes can affect the nutritional quality of most fruits and vegetables. This preliminary study was undertaken to determine the importance of genetics versus environment effects in watermelon Lcitrulline content, an amino acid that may help regulate blood pressure. Our results suggest that L-citrulline content can vary within a cultivar (one cultivar demonstrated a 0.4 to 4.9 mg/ml fresh sample deviation) even when grown and tested at one location. The data did not indicate a strong varietal difference on the average amount of L-citrulline accumulated (2.4 to 3.4 mg/ml fresh sample); more lines need to be screened to determine if breeding for high L-citrulline germplasm is possible. Location did not appear to significantly increase within-cultivar variation (one cultivar demonstrated a 1 to 4.9 mg/ml fresh sample deviation over two locations), this implies that it may be possible to develop lines with constantly high L-citrulline content across divergent growing environments.