title: Deficit irrigation and maturation stage influence quality and flavonoid composition of 'Valencia' orange fruit.
abstract: BACKGROUND
  Effects of continuous deficit irrigation (DI) and partial rootzone drying (PRD) treatments (50% ETc) in comparison with full irrigation (CI, 100% ETc) were investigated during 'Valencia' orange fruit maturation. Ultra-high-performance liquid chromatography/high-resolution mass spectrometry was used to quantify hesperidin, narirutin, tangeritin, nobiletin, didymin and neoeriocitrin in the fruit juice and peel.
  
  
  RESULTS
  No significant effect of irrigation was found on yield, juice soluble solids or acidity. Juice color was not influenced by irrigation or harvest date, whereas peel color increased during maturation and was more pronounced in CI and PRD fruits. Juice acidity reached a peak in May, while soluble solids increased linearly throughout maturation. Hesperidin was the major flavanone detected during maturation, with concentrations 200-fold higher in the fruit peel than in the juice. In the peel, narirutin, didymin and neoeriocitrin decreased while hesperidin, nobiletin and tangeritin increased with maturation. Narirutin synthesis in the orange fruit was insensitive to irrigation strategy. In fruit peels, PRD and DI induced the decline of hesperidin, nobiletin and tangeritin only in June, whereas in the juice, deficit irrigation treatments induced an increase in hesperidin and didymin.
  
  
  CONCLUSIONS
  These results suggest that deficit irrigation, in particular the conditions imposed with PRD, may cause a significant accumulation shift of total flavonoids from the fruit peel into the juice, with a positive impact on juice quality and nutritional value. Fruit compositional changes during maturation also suggest that late harvest can improve fruit palatability and nutritional quality under the cultural and environmental conditions of this study. © 2016 Society of Chemical Industry.
authors.affiliation: Department of Agricultural and Forest Sciences, University of Palermo, Italy.
authors.forename: Filipa S
authors.initials: FS
authors.lastname: Grilo
authors.affiliation: Department of Biological, Chemical and Pharmaceutical Science and Technology, University of Palermo, Italy.
authors.forename: Vita
authors.initials: V
authors.lastname: Di Stefano
authors.affiliation: Department of Agricultural and Forest Sciences, University of Palermo, Italy.
authors.forename: Riccardo
authors.identifier: http://orcid.org/0000-0003-2568-2880
authors.initials: R
authors.lastname: Lo Bianco
mesh_terms: D057914:Agricultural Irrigation / Q000295:instrumentation / Q000379:methods*; D032084:Citrus sinensis / Q000737:chemistry* / Q000254:growth & development / Q000378:metabolism; D003116:Color; D005419:Flavonoids / Q000737:chemistry* / Q000378:metabolism; D005421:Flavoring Agents / Q000737:chemistry / Q000378:metabolism; D005638:Fruit / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism; D011786:Quality Control; D014867:Water / Q000032:analysis / Q000378:metabolism*
chemical_list: D005419:Flavonoids; D005421:Flavoring Agents; D014867:Water
keywords: Citrus sinensis; UHPLC/HESI-MS; hesperidin; partial rootzone drying; peel color; soluble solids