The evaluation of 11 pear rootstocks has been carried out during the 1992-2001 period on 'Conference' cultivar in the IRTA's Experimental Stations of Lleida and Mas Badia (Girona, NE-Spain). The larger part are clonal rootstocks (quince and OHxF) some of them with interstem, one seedling rootstock and selfrooted trees of 'Conference'. Trees were planted in 1996 in Lleida and 1992 in Girona using a planting distance of 4 x 1.5m and 4 x 2m, respectively. Bloom time was essentially the same for all rootstocks. Harvest date was not affected by the rootstock and there were no differences on fruit firmness, fruit shape, sugar content (IR) and titratable acidity either between all the rootstocks or when quince types are compared to the other rootstocks. Significant differences were recorded on tree vigour even from the quince types. The most vigorous were the OHxF333 and selfrooted trees followed by seedling and OHxF69. All the OHxF selections provided higher vigour than quince types. From quince rootstocks, BA-29 and 'Comice'/MA had almost the same vigour and higher than MC, the weakest one. The use of interstem increased tree vigour on MA.
Highest cumulative yields per tree were obtained on all quince types and selfrooted trees and the lowest on seedling and OHxF types, specially OHxF-333. Interstem reduced yield although non significatively. When cumulative yields were adjusted by rootstock vigour and converted to tons per ha these differences increased and the highest was obtained on MC. Tree vigour and cumulative yields on all the rootstocks have been always higher in Lleida than in Girona. Yield efficiency was inversely correlated to tree vigour. The most efficient rootstocks was MC, 'Adams', 'Sydo' and 'Comice'/M-C, and the lowest with seedling and OHxF. Quince types provided always the largest fruit size and selfrooted, seedling and OHxF the smallest ones. Selfrooted trees and seedling showed the lower sensitivity to iron chlorosis, intermediate was recorded on BA-29 and OHxF333 and highest on MC, MA, 'Adams', 'Sydo' and OHx F69.