J. Agric. & Env. Sci. Alex. Univ., Egypt, 11(3). 2012 1 ENHANCING COLORATION AND QUALITY OF "CRIMSON" SEEDLESS GRAPE BERRIES CULTIVER USING MODIFIED ETHREL FORMULATIONS Karim M. Farag; Amr M. Haikal; Neven M.N. Nagy, and Yasmine S. Hezema Horticulture Department, Faculty of Agriculture, Damanhour University. Egypt. ABSTRACT "Crimson" Seedless (Vitis vinifera L.) grape is a late season, attractive, a very popular red seedless grape cultivar. In spite of the favourable characteristics of this cultivar, the problem remains a lack of adequate color intensity and uniformity in some regions. Moreover, research on this cultivar has been driven by a search for ways in which to increase the export output by increasing color. This study was conducted during two successive seasons 2009 and 2010 by using "Crimson" seedless table grapes. Vines were grown at Bader district, Beheira, Egypt. Vines were sprayed with a hand sprayer to the run off. The treatments included water as the control, Ethrel at 250 ppm, Ethrel at 250 ppm plus urea at 100 ppm, Ethrel at 250 ppm plus glycerol at 1% (v/v), urea at 100 ppm, and glycerol at 1% (v/v) and applied at veraison, while the second application followed first one by five days. The non-ionic surfactant Tween-80 was added to all treatments at 0.05% (v/v). It was found that, there is no treatment affected physical characteristics such as berry weight, berry size, juice volume, berry diameter and length. Adding glycerol to Ethrel in a formulation led to a significant increase of red berries percentage, total sugars concentration, TSS, while decreased green berries percentage, chlorophyll a, b contents. Both used enhancers (urea, glycerol) when added to Ethrel increased anthocyanin and carotene content in berry skin and TSS/acidity ratio. Thus, changing Ethrel formulation by incorporating either urea at a very low concentration or glycerol was able to consistently enhance color formation and uniformity of "Crimson" seedless cultivar under field conditions. Key words: Crimson seedless, Table grapes, Ethrel, Urea, Glycerol, Anthocyanin, coloration. INTRODUCTION "Crimson" Seedless (Vitis vinifera L.) grape is a late season, attractive, red seedless grape cultivar. Across the world, „Crimson Seedless‟ is currently a very popular table grape cultivar. The popularity of „Crimson Seedless‟ can be ascribed to its very distinctive sweet, juicy, flavour and elongated, pink berries. It has a crisp, firm skin with a juicy pulp and high sugar content, with half as glucose and half as fructose. Berries also contain some dietary fiber and vitamin C and contain adequate amounts of potassium and vitamin A (Passingham, 2004), another reason for its popularity could be that „Crimson Seedless‟ is a late maturing, red seedless grape which is not susceptible to berry crack thus allowing for a longer ripening period; and fruit kept in cold storage tends to remain in good conditions (Human, 2010). However, some of the main problems with the production of „Crimson Seedless‟ are related to its color and size. A further problem with „Crimson Seedless‟ color is that with increased yields and practices that are used to increase berry size, color is further