Fruit quality and volatile fraction of 'Pink Lady' apple trees in response to rootstock vigor and partial rootzone drying

BACKGROUND: Partial rootzone drying (PRD) is a novel deficit irrigation technique consisting in the alternatedwetting of only one side of the rootzone, which induces partial stomatal closure and increased water use efficiency.The effect of PRD and rootstock vigor on ‘Pink Lady’ apple fruit quality and aroma profile was studied usingsolid-phase micro-extraction in headspace and gas chromatography/mass spectrometry.RESULTS: PRD irrigation generally did not affect quality attributes, whereas it influenced the aroma of the applefruit. In particular, PRD improved the aroma of the fruit flesh, while it decreased the volatile fraction in the peel,where most of the compounds are concentrated. Taking into account the relative contribution of the flesh and peel(w/w) to the apple fruit, the volatile content of the entire fruit was increased by PRD irrigation in less vigoroustrees on M.9 rootstock, but reduced in more vigorous trees on MM.106 rootstock.CONCLUSIONS: Differences between the two rootstocks were probably due to different ability to extract soilwater by the two types of trees. A combination of the less vigorous rootstock and PRD irrigation may induce animprovement in the aroma composition of the apple fruit.2008 Society of Chemical Industry