EVALUATION OF QUINCE AND SELECTED 'FAROLD^®' PEAR ROOTSTOCKS FOR COMMERCIAL 'WILLIAMS B.C.' PRODUCTION IN URUGUAY

‘Williams B.C.’ pear was grafted on two pear rootstocks: ‘Farold^®40’ and ‘Farold^®69’, and on three clonal quince rootstocks: ‘BA 29’, ‘Adams’ and ‘EMC’ with and without ‘Beurré Hardy’ as an interstem. To evaluate the performance of these combinations in the south of Uruguay, grafted trees were planted in 2003 at INIA Las Brujas, ‘Wilson Ferreira Aldunate’ Experimental Station (34°40 S-56°20 W). Rows were 4.5 m apart and variable distance was used between plants according to rootstock: 1.70 m (‘BA29’, ‘Farold^®40’ and ‘Farold^®69’), 1.50 m (‘Adams’), and 1.30 m (‘EMC’). Observations on phenological, vegetative, and productive behavior of the ‘Williams B.C.’ scions were carried out each year. From 2004 onwards, trunk cross-sectional areas (TCSA) showed differences allowing rootstocks to be ranked in order of decreasing vigor: > ‘Farold^®69’ > ‘Farold^®40’ > ‘BA 29’ > ‘Adams’ > ‘EMC’. In 2014, trunk cross-sectional area on ‘Farold^®69’ was 198.7 cm^{2/sup> while a minimum of 53.8 cm2 was measured on ‘EMC’. Different rate of plant death occurred, having higher losses among ‘EMC’ and ‘Adams’ with interstem and all quince rootstocks without interstem. Cumulative fruit yields per plant of nine harvests ranged between 149.8 (‘BA29’ with interstem) and 73.5 kg tree-1 (‘EMC’). The best performances were recorded on ‘BA29’ with interstem, ‘Farold®40’ and ‘Farold®69’ pear rootstocks, with an average of cumulative production of 190 ton ha-1. The highest yield efficiency was obtained with ‘Farold®40’ rootstock (0.35 kg cm-2 TCSA) and with ‘BA29’ with interstem (0.30 kg cm-2 TCSA). Therefore, to achieve maximum pear production potential under Uruguayan conditions, rootstock quince ‘BA29’ with ‘Beurré Hardy’ as an interstem, ‘Farold®40’, and ‘Farold®69’ are the better options.}