Fruit quality of grafted watermelon may benefit from late harvest

Sound prediction of harvest maturity is particularly critical for non-climacteric fruit, such as watermelon, whose physiological maturation terminates at harvest and their quality steadily declines postharvest. Most common non-destructive maturity index for watermelon is the number of days past fruit setting. However, whereas the practice of grafting watermelon onto biotic and abiotic stress-resistant rootstocks has widened, the implications of this practice on ripening behavior remains largely overlooked. Hence, the evaluation of rootstock-mediated effects on watermelon fruit quality has relied by convention on a simultaneous harvest of grafted and self-rooted plants, assuming a synchronized maturation. Differences obtained in physicochemical components of fruit quality between grafted and self-rooted plants is thus limited to a snap-shot of quality at harvest while in fact it may partly or solely reflect differences in harvest maturity. Our main objective has been to characterize the evolution of physicochemical and phytochemical components of quality during watermelon ripening in response to grafting. 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 (30-50 days 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 color component a*. 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 45 dpa; whereas in non-grafted ones it was unchanged between 30-45 dpa and declined at 50 dpa. As ripening overall was retarded by grafting, fruit quality of grafted watermelon may benefit from belated harvest. ? Source Rootstock mediated effects on watermelon [Citrullus lanatus (Thunb.) Matsum and Nakai] ripening behavior and fruit physicochemical and phytochemical composition M.C. Kyriacou1, G.A. Soteriou1, A.S. Siomos2, D. Gerasopoulos2 1Agricultural Research Institute, Nicosia, Cyprus 2Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece V Postharvest Unlimited, ISHS International Conference, 10-13 June 2014, Cyprus, http://web.cut.ac.cy/postharvest/ The picture is by viveroslasala.com ? Key wordsPoscosecha?? ?postcosecha?? ?postharvest?? ?na-oes?? ??? ??? ???????? ????? ??? ?post-r?colte?? ????? ?? ??????????? ??? ?na-oogst?? ?post-raccolta?? ?Obr?bka po?? ?p?s-colheita?? ????????????????? ?hasat sonras??? ??? ?Ernte?? ????????????????? ????? ????????????? ?postcollita?? ?poskliz?ov頠 ????? ??? ??? ??? ?nakon branja?? ?pozberov頠 ??? ?obdelovanje zemlje po?? ?post-colleita?? ?????? ??????? ?pascapanen?? ??il?onn postharvest?? ??????? ?p?c ra?as?? ?derliaus apdirbimas po?? ?lepas tuai?? ??? ?? ???????? ?post-recoltare?? ??????? ??????? ???????????????????? ?????????????? ?????????????????? ?sau thu ho?ch?? ?????????????????? ?zangemva kwenkathi yokuvunaSand?a?? ??? ?watermelon?? ??? ??????? ????? ?akvomelono?? ?past?que?? ??????????? ? ?? ?watermeloen?? ?anguria?? ?arbuz?? ?melancia?? ???????? ? karpuz?? ? ?? ? ?? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ??? ????