Plant growth regulators increase the fruit size of ‘Spadona’ and ‘Coscia’ pears (Pyrus communis) in a warm climate

SummaryThe two main pear cultivars grown in the warm climate of Israel, 'Spadona' and 'Coscia', produce relatively small fruit. Over five consecutive years (2001 – 2005), the application of 0.12% (v/v) BoleroTM [8.6 mg l–1 gibberellic acid (GA3) plus 6 mg l–1 2,4-dichlorophenoxyacetic acid (2,4-D) plus 6 mg l–1 naphthaleneacetic acid (NAA)] at full-bloom, caused an appreciable and significant increase in fruit size without any deformation of the calyx-end, which is typical of GA3 treatment when applied at the same phenological stage to improve fruit set. GA3 alone did not increase fruit size. Application of 0.125% (v/v) PerlanTM [25 mg l–1 benzyladenine (BA) plus 25 mg l–1 GA4+7] at full-bloom + 14 d, increased fruit size via stimulation of fruit cell division (BA) and fruit cell enlargement (GA4+7), with no negative effect on fruit shape.