Influence of pedo-climatic conditions on the quality of iris pallida rhizomes

Abstract

The rhizomes of Iris pallida, known as orris root, are an important source of essential oils for the perfume industry and of the powder used for making gins and cordials. Rhizomes contain irones, ketone compounds formed from iridals during post-harvest ageing. Iris pallida is cultivated in Europe, mainly in Italy and France, and in Morocco and India. The Ital-ian product is highly sought after due to its qualitative characteristics. Little is known about the influence of pedo-climatic conditions on the quality of the cultivated rhizomes. Our investigation was carried out in the Iris pallida cultivation area of Tuscany (Italy) and intended to assess the possible relationship between the chemical profile of iridals, the climate, and soil properties. Seven farms were selected based on the significance of the cultivated surface, i.e., minimum area of 0.3 ha, and the proximity to the weather sta-tions. A climate survey was conducted. Soil was ana-lysed for the main physico-chemical characteristics and rhizomes for the content of iridals. Our results showed that despite the different phys-ico-chemical soil properties and different rainfall re-gimes that characterize the cultivation areas, the irid-als concentrations in rhizomes did not differ among farms. This supports the hypothesis that Iris pallida behaves like a hardy species by adapting well to different cultivation environments, especially to both non-calcareous and calcareous soils. The observed adaptability of this species to different environments might contribute to the spread of this crop even in marginal soils. This could generate more income for farmers. The cultivation of terrace soil could improve soil and water conservation, as well as decrease soil erosion. Further studies are needed to understand the dynamics of the accumulation of iridals in the rhi-zomes, and to identify the factors that influence the iridal transformation in irones.