Exploring plant-environment interaction in Iris pallida Lam.

Iris pallida essential oil, among the most expensive in perfumery, enriches many fragrances as a base note with its floral-woody nuances. Its violet-like scent is due to irones, ketone compounds produced during the storage phase of orris rhizomes, and originated from the oxidation of triterpenoid precursors called iridals. Orris, traditionally cultivated in Tuscany as an associated crop requiring minimal agronomic management, has experienced a progressive decline in Italian production over recent decades, despite the increasing demand from the perfume industry. To incentivize its cultivation, a deeper understanding of the critical aspects of the I. pallida production chain is necessary. A plant-environment interaction study was established to better understand the factors influencing rhizome quality and mass yield. Five I. pallida ecotypes traditionally cultivated for fragrance production were transplanted into five different areas and grown for three consecutive years. Biometric measurements were performed during the flowering stage and at the end of each annual cultivation cycle, and the analysis of iridal accumulation and irone production was carried out in every season. Results showed a strong environmental influence on ecotypes’ growth. Iridal and irone concentrations were found not to be a convenient trait to discriminate ecotypes, while rhizome weight was found to be relevant for irone hectare −1 yield prediction. Moreover, rhizome growth rate seemed to be influenced by soil characteristics, opening the way to optimization and simplification of orris agronomic management. The obtained results can potentially be exploited to maximize rhizome quality and select the best-suited ecotypes for each cultivation area. • Iris pallida shows remarkable adaptability across diverse pedo-climatic conditions. • I. pallida ecotypes mainly differ in phenotypic traits, shaped by the environment. • The in-depth examination of I. pallida cultivation allows to optimize rhizome yield. • This study provides a proof of genetic intra-species diversity in Iris pallida .