Self and cross pollination effects on pollen tube growth and fertilization in self-compatible almond<i>Prunus dulcis</i>‘Tuono’

Abstract

SummaryThe inbreeding consequences linked to self compatibility in the cultivated almond, Prunus dulcis (Mill) D. A. Webb were evaluated histologically in the self-compatible cv. Tuono. Self and cross pollen tubes grow at similar speeds in the pistil of ‘Tuono’. The pollen tubes reach the style base 4 d after pollination. The gametophytic interactions did not help in reducing the occurrence, at this level, of inbreeding effects. The development of the embryo sac stimulated by two types of pollination is differentiated when the pollen tubes reach the style base. However, the fertilization process, marked by the fusion of polar nucleus and the elongation of the embryo sac, shows a delay in the case of the selfed ovule. The differentiation of the pollen sac is in fact realized for 20% of the ovules 5 d after self pollination. In this case 80% of the embryo sacs have unfused polar nuclei. For the same period, 80% of the crossed ovules have polar nuclei which are already fused. The type of pollination seems to have a potential effect on ovule viability of embryo sacs which suggest that the inbreeding effects are revealed after fertilization.