Mineral accumulation in apple fruit as affected by spur leaves

The mineral composition of apple (Malus domestica Borkh.) fruit from spurs with artificially adjusted spur leaf areas was examined throughout fruit development. Primary leaf and/or bourse shoot removal at bloom or petal fall reduced Ca content during the growing season on 'Gala', 'Golden Delicious' and 'Royal Gala'. Bourse shoot removal 75 days after full bloom had a similar but less pronounced effect on final fruit Ca content for 'Royal Gala'. Primary leaves assisted movement of Ca into fruit earlier and were more efficient on a per leaf area basis throughout fruit growth than bourse leaves. Fruit Mg contents showed similar but less consistent responses to spur leaf removal compared with Ca. Fruit K contents and fruit fresh weight were similar from spurs whose primary spur or bourse shoots/leaves had been removed.