Fertilisation efficiency of semi- and fully-compatible European pear (Pyrus communis L.) cultivars

In Israel European pear (Pyrus communis L.) is grown in warm, sub-optimal climate conditions and the yield is low. Commercial orchards consist of 'Spadona' as the main cultivar, and 'Coscia', 'Gentile' and 'Spadochina' as its pollinators In a previous study, it was found that these three pollinators were semi-compatible with 'Spadona'. In the present study the fertilisation efficiency of the cultivars was compared using hand- and open-pollination. Differences in fertilisation efficiency characteristics (including seed number per fruit) were inconsistent, apart from an increase in 'Spadona' fruit diameter when pollinated by 'Spadochina'. Hence, these results indicate that 'Spadochina' exerted metaxenia a phenomenon which has not been described previously in European pear. However, this difference is not sufficient for the desired increase in yield. Therefore, a comparison between a fully- and two semi-compatible pollinators was carried out. Since 'Spadona' could not serve as a female parent in this kind of experiment, due to the S-RNase allele content of the cultivars, 'Coscia' served as the female parent, 'Gentile' as the fully-compatible pollinator and 'Spadona' and 'Spadochina' as the semi-compatible pollinators. As this pear-couple composition is not included in orchard designs, only hand-pollination experiments could be carried out. The trial revealed a high and significant increase in fruit set and seed set by fully-compatible compared to semi-compatible pollinators.