*2.2. Measurements and Analyses*

Fruits were weighed and equatorial and meridian diameters were determined with a Vernier caliper at harvest. Yield and number of fruits per hectare were estimated. All underdeveloped fruit were considered unmarketable. Cross-sections of marketable fruit typical for each of the five scion cultivars are presented in Figure 1. Quality assessment was performed by sampling randomly three fruit from each plot. All sampled fruit for quality assessment purposes had been set on the same calendar date ± 1 day and harvested simultaneously 40 ± 1 days later. An electronic caliper was used at two representative points on each cross-sectioned fruit for assessing fruit rind. Watermelon flesh firmness was recorded by a TA.XT plus Texture Analyser (Stable Micro Systems, Surrey, UK) as described previously [11]. The Texture Analyser protocol was set to measure flesh firmness as the maximum resistance force to penetration to a depth of 50 mm around the heart of each cross-sectioned fruit. A Minolta CR-400 Chroma Meter (Minolta, Osaka, Japan) was used to assess flesh color at two loci in the heart region of each fruit in cross section using the CIELAB color space to record lightness (L\*), chroma coordinates a\* and b\*, chroma (C\*), and hue angle (h◦) [12]. A homogenate was obtained from the excised heart of each fruit using a Vita Prep 3 (Vita-Mix Corp., Cleveland, OH, USA) blender under low speed to prevent foaming. Using a digital refractometer (RFM870; Bellingham-Stanley Ltd., Kent, UK), part of the homogenate was used, after double cheesecloth filtration, for determining juice total soluble solids content (TSS) at 20 ◦C. A pH electrode (SevenMulti, Mettler-Toledo GmbH, Schwerzenbach, Switzerland) was used for measuring the pH of the juice. Falcon tubes (50 mL), instantly dip-frozen in liquid nitrogen, were used to store part of the homogenate at −80 ◦C for further chemical analyses.

**Figure 1.** Intact and cross-sectioned watermelon fruit of cvs. Petite, Vivlos, Pegasus, Extazy and Esmeralda.

Lycopene extracted in hexane was determined according to the method of Perkins-Veazie et al. [13]. Lycopene was quantitated against pure hexane on a Jasco V-550 UV-VIS spectrophotometer (Jasco Corp., Tokyo, Japan) at 503 nm using the extinction coefficient of 17.2 <sup>×</sup> 104 M−<sup>1</sup> cm−1. Non-structural carbohydrates (glucose, fructose, sucrose) were analyzed by liquid chromatography on an Agilent HPLC system (Agilent Technologies, Santa Clara, CA, USA) equipped with a 1200 Series quaternary pump and a 1260 Series refractive index detector using a 4.6 × 250 mm carbohydrate column at 35 ◦C (Waters, Milford, MA, USA) and acetonitrile:water (75:25) as mobile phase at 1.4 mL min−<sup>1</sup> for separation (detailed description provided in Kyriacou et al. [1]). Quantification was performed against external standard calibrating curves with a coefficients of determination (*R*2) > 0.9999. Citrulline was also analyzed on the same HPLC system equipped with an Agilent 1260 Series PDA detector using the method of [1].
