Contributing to the knowledge of the fertilisation process in four apricot cultivars

Abstract

Causes of poor crops in apricot were investigated by studying the reproductive process after pollination. The evolution of the ovules and the growth of the pollen tubes were determined. Also the fertilisation of the ovules and the fruit set obtained, when pollination was delayed, were examined in two groups of cultivars with different fruiting behaviour. ‘Beliana’ and ‘Palstein’, two cultivars that consistently set good yields, presented ovules that mature earlier and in larger number than those of ‘Guillermo’ and ‘Bergeron’, characterised for year-to-year low fruit production. Pollen tubes also grew faster in the first group of cultivars. Differences found between both groups of cultivars, seem to be related to the ability of the ovules to develop and mature after anthesis, and around 50% of them only had a mother cell without an embryo sac, suggesting that development of those ovules was stopped at an early stage. This fact critically influenced fertilisation and, therefore, fruit set. There seem to be a good correlation between percentages of mature ovules a few days after anthesis, the percentages of fertilised ovules and final percentages of fruit set.