433 Watermelon Genetic Resources in Turkey and Their Characteristics N. Sari and İ. Solmaz Dept. of Horticulture Fac. of Agric. Univ. of Cukurova Adana Turkey H. Yetisir Dept. of Horticulture Fac. of Agric. Univ. of Mustafa Kemal Hatay Turkey H. Unlu Dept. of Horticulture Fac. of Agric. Univ. of Suleyman Demirel Isparta Turkey Keywords: watermelon, fruit and seed characterization, genetic resources Abstract Turkey is the second largest watermelon producing country after China. Although Turkey is not the origin of watermelon, it has valuable watermelon genetic resources which mainly consist of local genotypes. University of Cukurova has one of the largest collections of the country and has been studying the genetic collections since early 1990’s. Today University of Cukurova has a collection of approximately 250 genetic materials. In this study, 15 provinces in 5 different regions (Southeastern Anatolia, Aegean, Marmara-Thrace, Middle Anatolia and Mediterranean regions) of Turkey were visited in summer and fall season of 2004. 134 watermelon genotypes were collected. Fruit (size, shape, ground color of skin, intensity of color, presence of stripes, flesh color) and seed (size, ground color of testa, secondary color of testa, patches at hilum, and patches at margin) of collected watermelon genotypes were characterized. INTRODUCTION The genus Citrullus Schard. Ex Eckl and Zeyh. contains four diploid species: Citrullus lanatus (Thunb.) Matsum and Nakai, found in tropical and subtropical climates, includes the cultivated watermelon (C. lanatus var. lanatus) that thrives in West Africa and is also called ‘egusi’ melon, and the preserving melon (C. lanatus var. citroides) that is grown in Southern Africa and is called ‘tsamma’ melon (Whitaker and Bemis, 1976). C. colocynthis (L.) Schard (‘bitter apple’) is a perennial species cultivated in sandy regions throughout northern Africa, southwestern Asia, and the Mediterranean (Zamir et al., 1984; Burkill, 1985; Jarret et al., 1997). C. ecirrhosus Cogn. is a perennial, wild species (Meeuse, 1962). C. rehmii De Winter is an annual, wild species (De Winter, 1990). The last two species are endemic to the desert regions of Namibia (Meeuse, 1962). During last century, production area of watermelon has steadily increased. Watermelon accounts for 2% of the world area used for vegetable cultivation. Although many watermelon cultivars have been developed in different regions of the world during last century, there is an ongoing need for developing new watermelon cultivars, especially for increased disease and pest resistance (Levi et al., 2001). Plant genetic resources are very important for breeding (Engels et al., 1995). Collecting and evaluating of plant germplasm has great importance in improvement of sustainable agriculture (Krasteva, 2000). Usage of genetic resources is as old as history of agriculture. Hundreds of plants have been bred over years and thousands of varieties have been developed by natural and artificial selection. Genetic erosion was caused by natural occurs in earlier times whereas recently forest fire, misuse of forest and agricultural fields, excessive and undeliberate use of fertilizer and pesticides have caused decrease of plant genetic diversity. Nowadays, many serious studies have been conducted for preserving genetic resources in many countries (Anonymous, 2003). Turkey is an important and rich genetic diversity center because the country is located in intersection of Euro- Siberian and Irano-Turanian and Mediterranean Phyto- geographic regions. In addition, Turkey is an immigration road as a bridge between three continents and Anatolia had climatologically different regions (Tan, 1998). Proc. III rd IS on Cucurbits Eds. R. McConchie and G. Rogers Acta Hort. 731, ISHS 2007