Blooming Phenograms, Pollen Production, and Pollen Quality during Storage of Pistachio Cultivars in New Mediterranean Growing Areas

Pistachio (Pistacia vera L.) is a dioecious, anemophilous, and drought-resistant fruit tree species. It is cultivated in new Mediterranean areas, including the regions of southern Italy (Apulia and Basilicata). It has been estimated that over 40,000 ha are suitable for pistachio cultivation in areas infected by Xylella fastidiosa subsp. pauca. As a newly introduced species, knowledge of its biological reproductive behaviors in its new areas of spreading is essential for appropriate agronomic planning and management. This two-year study (2022 and 2023), carried out in the countryside of Stigliano (MT, Italy), had the objective of evaluating the flowering phenograms, pollen production, and assessing protocols for the conservation and extension of pollen viability, of the most widespread cultivars. A slight delay was observed in the blooming phenograms, compared to other cultivation Mediterranean areas, such as Spain or Sicily. Furthermore, the overlap between female and male phenograms was partial. No significant differences were observed in the polliniferous aptitude of the two male cultivars. Among the different protocols tested, the pollen storage at 33% relative humidity and a temperature of −80 °C maintained the pollen germinability above 50% for up to three weeks. These findings highlight the importance of controlled environmental conditions in preserving pollen viability over extended periods, providing valuable insights for agricultural and botanical research that relies on maintaining pollen viability for breeding and genetic studies.