Exploring Pistacia vera pollination: Phenological and aerobiological insights into the main commercial varieties

Abstract

The pistachio tree (Pistacia vera L.) is a dioecious anemophilous crop with a high economic importance. Nevertheless, it is scarce knowledge about floral phenology and pollen aerobiology of their varieties. Pistachio crop surface is sharply increasing in the Mediterranean basin, due to it is highly adaptable to abiotic stresses. This favors a more sustainable and biodiverse agriculture in the dry areas. The main problem that pistachio crop is facing today are phenological reproductive asynchronies between male and female trees, increased by climate change. The present work analyses phenological and pollen aerobiological dynamic of 23 varieties (9 males and 14 females) for 2019 to 2023 in an orchard located at Córdoba (South Spain). Results showed a staggered flowering timeline firstly in males, being the earlier male varieties, Azkar Randy, C-special, and IA13, flowering in early March, while later males were IA3 and Nazar flowering up to 2 weeks after. The aerobiological pollen curve reflected this gradual although showing time differences between years. The most disturbing results correspond to female cultivars flowering later than males, with a short matching period in cases. Statistics identified the different degrees of reproductive synchronization between sexes, revealing significant variations depending on varieties' couples. The highest phenological matching was for Randy with Golden-Hill (80 %), Avdat with IA13 and IA3 (75 %) and IA3 with Kastel (70 %). However, traditional couples like Peter and Kerman showed a lower coincidence (40 %). To note that only 16 of the 126 potential couples, presented a matching percentage ≥60 %, which is an acceptable minimum threshold to decide to plant together. The results of the study are essential for understanding the pistachio's flowering patterns, pollen aerobiology and potential couples' matching, helping companies and farmers for a better pistachio crop planning and management.