EFFECT OF PROHEXADIONE-CA ON GROWTH REGULATION, YIELD, FRUIT SET AND RETURN BLOOM, IN ‘BLANQUILLA’ AND ‘CONFERENCE’, THE TWO MAIN PEAR CULTIVARS GROWN IN SPAIN

Prohexadione-Ca is an inhibitor of gibberellin biosynthesis. Trials were carried out in ‘Conference’ and ‘Blanquilla’ orchards in two different growing areas (Girona and Lleida) from 2000 to 2002 in order to study the possible adoption of Prohexadione-Ca as a pear growth regulator. Prohexadione-Ca was applied in different doses ranging from 100 to 400 g/ha and distributed in 3 to 6 foliar treatments. Application of Prohexadione-Ca produced a significant reduction in vegetative growth as expressed in terms of shoot length, however important differences were noted between cultivars and treatment schedules. In some cases improvements in fruit size were also detected. The maximum seasonal dose to prevent a reduction in return bloom was established as approximately 4 kg/ha for Conference and 6 kg/ha for Blanquilla. Our data suggest that Prohexadione-Ca may be a suitable option for growth regulation in pear orchards. Even so, it is necessary to carry out further studies into treatment schedules to improve growth reduction and fruit set and prevent reductions in return bloom.