title: Relationship between polyphenol oxidase activity and nutrition, maturity and quality parameters in flat peach.
abstract: BACKGROUND
  Polyphenol oxidase (PPO) is one of the main factors that determine postharvest stability and therefore commercial possibilities of peach orchards. Since the activity of this enzyme depends on several variables of different nature, stating the relationships among them is essential to manage crop inputs so as to achieve the desired quality.
  
  
  RESULTS
  Multivariate projection techniques were used to identify these relationships throughout on-tree maturation in flat peach samples that had received different fertilisation doses, but harvested in equal conditions of soluble solids, fruit weight, diameter, firmness and skin and flesh colour. A relatively low fertilisation dose that was enough to avoid any lack of nutrients provided the lowest crop yield, but also with the lowest PPO activity. Fruit N/Ca ratio turned out to be a better indicator of PPO activity than isolated nitrogen or calcium content. Nutrient analyses on leaves did not have strong correlations with any significant parameter. The most useful variables to predict PPO activity before harvest were fruit firmness and skin colour, both of them read at the onset of on-tree maturation.
  
  
  CONCLUSIONS
  High fertilisation doses resulted in greater yields, but also with higher PPO activity, which is detrimental for the commercial chances of the fruit.
authors.affiliation: Departament d'Hortofruticultura, Botànica i Jardineria, Universitat de Lleida, Av. Rovira Roure, 191, E-25198, Lleida, Spain.
authors.forename: Miquel
authors.initials: M
authors.lastname: Pascual
authors.forename: Josep M
authors.initials: JM
authors.lastname: Villar
authors.forename: Joan
authors.initials: J
authors.lastname: Lordan
authors.forename: Francisco
authors.initials: F
authors.lastname: Fonseca
authors.forename: Víctor
authors.initials: V
authors.lastname: Falguera
authors.forename: Josep
authors.initials: J
authors.lastname: Rufat
mesh_terms: D004156:Catechol Oxidase / Q000378:metabolism*; D005308:Fertilizers; D005638:Fruit / Q000737:chemistry / Q000201:enzymology* / Q000254:growth & development*; D015999:Multivariate Analysis; D018515:Plant Leaves / Q000737:chemistry; D018521:Plant Physiological Phenomena; D027861:Prunus
chemical_list: D005308:Fertilizers; D004156:Catechol Oxidase
keywords: N/Ca; fertilisation; flat peach; nitrogen; polyphenol oxidase