Evaluation of pollination as the cause of erratic fruit set in apricot 'Moniqui'

Apricot (Prunus armeniaca L.) is a species particularly prone to erratic fruit set. However, the causes of this behaviour are poorly understood since the main limitation in the study of erratic fruit set lies in the difficulty of evaluating all its possible causes in orchard conditions. This results in the eradication of interesting apricot cultivars, such as 'Moniqui', in spite of their increasing commercial demand due to their good organoleptic qualities. Ln this work the influence of pollination deficit in erratic fruit set is ascertained in orchard conditions and the self-compatibility and intercompatibility relationships among four of the main Spanish apricot cultivars are also studied. While 'Moniqui' is self-incompatible, 'Bulida', 'Canino' and 'Paviot' proved to be self-compatible. Likewise, all the intercrosses between them behave as compatible. An evaluation of both fruit set and pollen tube behaviour in random and supplementary pollinated flowers with pollen from 'Canino' in a commercial orchard of 'Moniqui' shows that fruit set in these conditions is limited by the absence of compatible pollen. This fact, together with the wide range of chilling requirements recorded for these cultivars may lead to poor production due to pollination problems. The situation here recorded might be applicable in other geographical areas and cultivars, since the number of apricot self-incompatible cultivars is gradually increasing. Furthermore, the approach used can also be applied to other situations and species, since it allows the isolation of pollination failure from other possible factors affecting fruit set.