Growth and yielding of the several apricot cultivars on the ‘Somo’ seedling and vegetative rootstock Pumiselect®

Since many years the usefulness of different rootstocks has been estimated because of the cropping level, the growth, the physiological incompatibility between scion and rootstock and the mortality of the apricot trees. The Myrobalan, apricot seedlings, ‘Wangenheim Prune’ plum tree cv. and other rootstocks were evaluated in the earlier investigations. The study on the Lower Silesia area was conducted at the Fruit Experimental Station of the University of Environmental and Life Sciences of Wrocław, in 2006–2011. One year old apricot trees grafted on the Pumiselect® vegetative rootstock were planted in spring of 2006, at a spacing 4.0 × 3.2 m (780 trees per 1 ha), in 4 replications with 3 of ‘Bergeron’ or 4 of ‘Harcot’ and ‘Hargrand’ trees per plot. At the same time the apricot collection was established. Trees of the 9 cultivars were planted at a spacing 4.0 × 4.0 m (625 trees per 1 ha). During the disadvantage weather conditions at the first four years of cropping the significant highest total yield over 40 kg per tree was recorded with ‘Harcot’ on the Pumiselect® rootstock. The other cultivars did not exceed 30 kg of fruit but all trees characterized the weakest growth in this rootstock. The previous investigation did not clear confirm the usefulness of Pumiselect® as a vegetative apricot rootstock for ‘Hargrand’ cv. because of the precocious trees decline and too low fruits in case of ‘Bergeron’ tree. The apricot trees on ‘Somo’ seedling growth stronger. Taking into account the yield, fruit quality and also the tree health status ‘Harcot’, ‘Heja’, ‘Karola’ and ‘Leskora’, ‘Łańcut’ cvs. were recognized as a suitable for commercial orchards on the Lower Silesia area.