The response of young ‘Braeburn’ and ‘Oregon Spur Delicious’ apple trees growing under an ultrahigh density planting system to soil-applied paclobutrazol II. Effect on fruit quality at harvest and during storage

Abstract

Paclobutrazol (PBZ) at 0 or 250 mg (ai)/tree was applied as a soil-drench in autumn of either 1989 or 1990 to ‘Braeburn’ or ‘Oregon Spur Delicious’ (OSD)/MM.106 apple ( Malus domestica Borkh.) trees growing in an ultrahigh-density planting system. A repeat application of PBZ at 250 mg (ai)/tree was made in autumn 1993 to half of the trees previously treated in 1989 or 1990. Across the 6 years of study, PBZ reduced fruit weight by 8.2%, and fruit length:diameter ( L:D) ratio by 3% in both cultivars at harvest. PBZ also reduced mean total soluble solids in both cultivars. Flesh firmness increased for ‘OSD’ and decreased slightly for ‘Braeburn’. PBZ treatment of the trees did not modify the storage behaviour or the quality parameters for either ‘Braeburn’ or ‘OSD’.