Breeding system in Olea ferruginea Royle (Oleaceae): comparative performance of staminate and perfect flowers in reproductive assurance

ABSTRACTOlea ferruginea, a wild widely distributed species of the olive lineage, exhibits andromonoecy with protogynous perfect (hermaphrodite) and staminate (male) flowers. The present communication elucidates the differential performance of staminate and perfect flowers in reproductive assurance. The flowering chronology and function of perfect and staminate flowers in the breeding system were investigated to understand the breeding behavior of the species. In terms of breeding behavior, pollen from staminate and perfect flowers was used to establish their role in breeding system under different pollination treatments. Results indicate higher pollen viability, germination, and pollen tube growth of staminate than perfect flowers. Results from pollen counts and morphological investigations show slight differences in both types. The species is self-incompatible which is indicated by pollen germination, the average number of pollen tubes in the style, and the fruit set following self and cross-pollination. Hand cross-pollination improves natural fruit set, especially when pollen from staminate flowers was used. Although the relict role of attracting pollinators cannot be fully discarded, it is suggested that the main benefit supplied by the formation of staminate flowers in olives is to promote male fitness by raising pollen output at the population level.KEYWORDS: Olea ferrugineaperfect flowersstaminate flowerspollinationpollen germinationpollen tubes AcknowledgmentsThe authors are highly thankful to the Head, Department of Botany, BGSB University Rajouri for help and support during the present study. National Mission on Himalayan studies (NMHS) is greatly acknowledged for financial support under fellowship Grant No: GBPNI/NMHS- 2018-19/HSF-24-02/153. We also like to thank the editor and anonymous reviewers for critically reviewing the manuscript.Disclosure statementWe hereby declare that we have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.Author contributionsSajid Khan: Data curation, Methodology, Software, Formal analysis, Visualization, Writing – original draft, Writing – review & editing. Priyanka Kumari: Data curation, Writing – review & editing. Susheel Verma: Conceptualization, Supervision, Data curation, Methodology, Formal analysis, Investigation, Project administration, Resources, Funding acquisition, Visualization, Validation, Writing – original draft, Writing – review & editing.Data availability statementThe datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found in the article/Supplementary Material.Additional informationFundingThe work was supported by the Ministry of Environment, Forest and Climate Change.