Analysis of the variability and correlations of floral biology factors affecting fruit set in apricot in a Mediterranean climate

Floral biology factors which affect fruiting in apricot, such as flower bud production, flower production, flower bud drop, flowering time, percentage pollen germination, height difference between the stigma and the superior plane of the anthers, percentage of aborted pistils, autogamy level, fruit set and fruit production, have been studied for 3 consecutive years in 43 apricot cultivars and selections grown in a Mediterranean climate. An important genetic diversity has been found in the set of evaluated apricot genotypes and significant differences were found among them in all attributes studied. Significant year-by-year variation has been shown for flower bud production, flower bud drop, flowering time, autogamy level, fruit production and fruit set.High correlation existed between some floral biology factors. Flower bud drop and pollen germination were correlated significantly with flowering time. Flower production influenced significantly fruit production, which was highly correlated with fruit set. Significant negative correlation was found between autogamy level and height difference between the stigma and the superior plane of the anthers. Significant negative correlation between percentage of flower bud drop and flower production was observed, while late-flowering genotypes with high chilling requirements showed higher percentages of flower bud drop than early-flowering genotypes.