Effects of Biological Factors and Temperature Elevation on Stigmatic Receptivity and Pollen Tube Growth in Diploid and Hexaploid Plum Genotypes [<scp><i>Prunus salicina</i></scp> and <scp><i>Prunus insititia</i></scp>]

ABSTRACT Premise of the study. Biological factors and environmental stresses are predominant elements affecting the progamic phase of sexual plant reproduction. Thus, new knowledge is needed to select and develop cultivars adapted to these changes. This work was conducted to evaluate the pollen growth dynamics and the stigmatic receptivity at normal and elevated temperatures, in 12 Tunisian plum genotypes selected based on six different biological factors. Methods. The pistils were hand‐pollinated using their own pollen, and then the dynamics of pollen tube growth and stigma receptivity of Tunisian plum genotypes were surveyed under ambient temperature and under 35 °C. Key results. Results showed that the differences in flower size, geographical origin and drought tolerance did neither affect pollen growth dynamics nor stigma receptivity. However, the polyploidization enlarged the stigmatic receptivity but does not affect the pollen dynamics. Flowering time and wild plantation fasten the pollen growth and enlarge the stigmatic receptivity. We assume that, in particular case, the flowering plants seem to opt for an enlarged stigmatic receptivity and a rapid pollen growth as reproductive strategies to ‘ hold on for dear life’ . Experiments conducted at 35 °C showed that the temperature elevation accelerates pollen growth dynamics, while it shortens the stigmatic receptivity period. In particular, two accessions: the wild plum ‘Sauvage’ and the late flowering ‘Tasstour Hamra Tardive’ showed faster pollen growth and enlarged stigmatic receptivity, compared to other accessions. Conclusion. The main relevant conclusion of this work resides in the identification of the best adapted Tunisian genotypes that could be selected as pollen sources to extend the pollination period. Especially, accessions presenting a tolerance to high‐temperature deserve serious attention.