28 Watermelon, Cantaloupe and Honeydew Penelope Perkins-Veazie, John C. Beaulieu and Muhammad Siddiq WATERMELON Introduction Watermelon (Citrullus lanatus) is adapted to many areas of the world and is grown in 96 countries (National Water- melon Promotion Board [NWPB], 2011). The largest pro- duction areas globally are China, Turkey, Iran, the United States, and Spain, respectively (Boriss et al., 2006). There are seeded and seedless genotypes with over a thousand va- rieties among these genotypes (NWPB, 2011). Watermel- ons can have a flesh color of white, yellow, orange, pink, red, or mixed red and yellow (Bang et al., 2010). Seeded varieties may be open pollinated (heirloom) or hybrids. In the United States, seedless watermelons make up 95% of the total watermelon acreage. The few seeded watermelons still produced are generally from pollinators used to get seedless watermelons or for traditional (“heirloom”) types favored regionally. Once used as a dessert fruit primarily for its sweet, crisp qualities, watermelon has garnered interest as a source of ly- copene and beta-carotene and the nonessential amino acid, arganine precursor, citrulline. These compounds have pur- ported antioxidant and anti-inflammatory activity. Addi- tionally, watermelon is an excellent source of vitamin C and vitamin A (Table 28.1). The total world production of watermelons was 89.15 million metric tons (MMT) in 2010, which reflected over 250% increase as compared to 1990 production of 34.85 MMT (FAO 2011). Leading watermelon-producing coun- tries were China (56.65 MMT), Turkey (3.68 MMT), Iran (3.47 MMT), Brazil 1.87 MMT), and the United States (1.87 MMT). China alone accounted for almost two-thirds of the total watermelons produced in the world (FAO, 2011). Mexico, Spain, the United States, Kazakhstan, and Viet Nam were the leading exporters, and the United States, China, Germany, Canada, and France were the leading im- porters of watermelon in 2009 (FAO, 2011). Total volume of watermelon used in the United States in 2010 was 11.2 billion kg, with 19% imported, 6% exported, and a value of $460 million (NASS, 2011). US consump- tion in 2011 was 34.1 kg watermelon per capita; the con- sumption trends have changed from a seasonal to a year- round fruit, primarily through imports during the winter months. Botanical structure Watermelon is botanically a fruit, a fleshy berry with tis- sues derived from the pericarp (Fig. 28.1) (Barber, 1909). The fruit flesh is consumed, rather than the rind, and flesh separates along the placental bundles, without forming a true cavity (Barber, 1909). The peel is the epicarp. Usually the hypoderm, outer and middle mesocarp are referred to as the rind, and the edible flesh or placental tissue refers to the inner mesocarp and area and placental area around ovules or seeds. Locules are formed in placental tissue around a center core (heart), and seeds are found in the locules (Lebo, 1932). The fibers seen in between locules and heart are referred to as the united lateral bundles (Esau, 1977). The dense, nonseparating tissues contain large cells, making the fruit sensitive to bruising during harvest and handling, despite the tough pericarp. Seedless watermelons Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging, First Edition. Edited by Muhammad Siddiq. C  2012 John Wiley & Sons, Inc. Published 2012 by John Wiley & Sons, Inc. 549