Evolution of watermelon fruit physicochemical and phytochemical composition during ripening as affected by grafting

Abstract

Flesh reflectance colorimetry, mechanical texture analysis, pH, titratable acidity (TA), and soluble solid (SS), soluble carbohydrate, lycopene and citrulline content of watermelon fruit were assessed throughout ripening (30–50days post-anthesis; dpa) in grafted and self-rooted plants. Grafting increased firmness, TA, and lycopene content though it delayed its peak. Lycopene content was mostly ripening-dependant, highly correlated and synchronous with changes in pulp chroma (C∗) and colour a∗. The sweetness was affected only by ripening. However, total sugars and SS peaked later in fruit of grafted plants than in non-grafted ones, and significant interaction of ripening with grafting was observed. Citrulline content increased with ripening in fruit of grafted plants, reaching a peak at 45dpa; whereas in non-grafted ones it was unchanged between 30 and 45dpa and declined at 50dpa. As ripening overall was retarded by grafting, fruit quality of grafted watermelon may benefit from belated harvest.