PEAR ROOTSTOCK BREEDING IN FRANCE

Abstract

Rootstock breeding programmes were first undertaken on quince at the INRA Fruit and Ornamental Plant Breeding Unit of Angers; and they led to the registration of 'BA29' (for 'Williams' cultivation) and 'Sydo' (for 'Conference' and 'Doyenne du Comice' cultivation). In order to enlarge the scale of rootstock-induced vigour, programmes now focus on pear (Pyrus). Selections have been made among seedlings of open-pollinated Pyrus nivalis, P. communis and P. heterofolia. Ability to propagate, compatibility, tolerance to fire blight (Erwinia amylovora), induced vigour, productivity and fruit size have been evaluated. One pear rootstock, ‘Pyriam’ (P. communis), has been released and two parents, G28-120 (P. nivalis) and P2532 (P. heterofolia), have been selected. ‘Pyriam’ is tolerant to fire blight, has good ability to propagate, very good compatibility with scion cultivars and straight growth in the nursery without branching. It induces the same productivity as 'BA29' (higher induced vigour and production); fruit size is higher than when using 'OHF333'. It is well adapted to ‘Williams’ cultivation in the south-east of France where it shows homogeneous and durable production compared to 'BA29' or 'OHF333'. G28-120 induces agronomic behaviour quite similar to 'BA29' (same level of induced vigour and production). P2532 shows high productivity (same level as 'BA29') and very good ability to propagate. Interspecific hybridization using 'Pyriam' as female parent began in 1997. To meet Northern Europe demand, crosses have been made with G28-120 and P2532 as male parents, in order to improve the agronomic level while inducing low vigour. Selection for fire blight tolerance and behaviour in the nursery has been conducted, and evaluation of the ability to propagate has just begun. For Southern Europe demand, collaboration has been established with the IRTA of Catalonia (Units of Cabrils and Mas Badia). Mediterranean species are used as male parents to introduce tolerance to iron-chlorosis and water shortage. In France, hybrids are still selected in the nursery for their growth habit and their compatibility with 'Williams'; in Spain, the study of tolerance to iron-chlorosis is in progress (using in vitro tests and orchard evaluations).