Fig. 2

Physiological characterization of ripening. a Evolution of color during fruit ripening: the standard citrus color index CCI, based on Hunter L, a, b system [86], was used to measure color change (Y axis). Negative values are indicative of green color, while positive ones of orange color, 0 signals color break. It can be appreciated that at 189 DPA ARR peel has turned to orange while in HER is still green. b Evolution of titratable acidity during fruit ripening, measured as grams of citric acid per 100 ml of juice (Y axis). The bar graph shows that at 126 DPA ARR has half the acidity levels than HER, while at 189 DPA the acidity of the 3 cultivars is still similar. c Evolution of maturity index as the rate of BRIX and acidity. It is evident that at 126 and 154 DPA, MI is higher in ARR and lower in HE with respect the control CLE, which is in agreement with the early and late phenotypes that characterize ARR, HE, respectively. At 189 DPE MI was similar in the 3 cultivars. X axis represents days post anthesis (DPA) and error bars indicate SEM