Articles
SELECTION OF PEAR SEEDLINGS (P. COMMUNIS L.) AS POTENTIAL CLONAL ROOTSTOCKS: PRELIMINARY DATA
While quince has a good dwarfing aptitude and induces early bearing, it is very sensitive to viruses and calcareous soils and shows poor compatibility with some leading cultivars, e.g. ‘Bartlett’. In response to these problems, old local pear cultivars, used in the past as a source of hardy seedlings, were included in a program aimed at selecting clonal pear rootstocks suitable for high density planting (HDP) because of their dwarfing or semi-dwarfing ability.
Some 1000 open pollinated seedlings obtained from cvs ‘Mora di Faenza’ and ‘Volpina’ were sorted into four groups by stem height after two years in the nursery.
Most of the vigorous seedlings were discarded, and a total of 530 trees were planted in a non-irrigated selection plot and trained as stool -bed stocks.
The shoots were girdled at the bottom when 30 cm long with a thin wire.
The following data were recorded over three years for each plant: number of shoots and feathers, height of the tallest shoot, thorniness, rooting.
Over 95% of the mother stools produced up to 8 shoots, and those with more than 9 shoots increased over three years from 0.5% to 7.5–16.7%. Rooted mother stools ranged from 70 to 92% on average, with no statistical differences among progenies.
No correlation was found between vigour of the mother and, respectively, rooting, feathers and thorniness.
The rooted shoots were grafted to ‘Bartlett’ after one year in the nursery and planted in a selection field to evaluate compatibility, dwarfing ability and early bearing.
One year after planting a marked variability in terms of vigour and aptitude to induce scion feathering was found.
No correlations between mother stool vigour and trunk diameter or stem growth of the scion were found.
Some of the most promising selections were tested for in vitro propagation with good results.
Further research is in progress to find more suitable traits for early screening of the most dwarfing rootstocks.