OPTIMISING THE NUTRACEUTICAL PROPERTIES OF SAFFRON CULTURES: APPLICATION OF A BACTERIAL CONSORTIUM TO ENHANCE ACCUMULATION OF BIOACTIVE COMPOUNDS AND SOIL BIODIVERSITY

Saffron (Crocus sativus L.) is an autumn-flowering geophyte known for its stigmas. However, the stigmas, stamens, and petals contain several bioactive compounds that can be used for pharmacological and nutraceutical purposes. Plant-microbe interactions have been shown to influence plant growth and the accumulation of bioactive compounds. Therefore, the use of bacterial inoculants could be a sustainable tool to improve the production of bioactive molecules. The aim of this study was to evaluate the effect of a selected bacterial consortium inoculation on saffron plant growth and bioactive compound accumulation in stigmas and petals. Two-year field and greenhouse experiments were conducted during the 2022 and 2023 growing seasons. The saffron corms were soaked in the bacterial inoculum for one hour and dried overnight. The control group was treated with water using the same procedure. The growth of the plants was monitored in both greenhouse and field experiments. During the flowering stage, leaves were collected for chlorophyll estimation, and stamens and petals were analysed for carotenoids, phenolic content, and antioxidant activity. Moreover, stigmas were processed to analyse the main bioactive compounds of saffron, including picrocrocin, safranal, and crocin, following ISO protocols. Soil samples were analysed for enzymatic activity (1-dehydrogenase activity - DHA) and microbiota structure (16S rRNA gene metabarcoding by NGS). Results showed that bacterial inoculation had a positive impact on saffron plants, resulting in earlier and more abundant flowering, as well as higher accumulation of bioactive compounds compared to the control. Furthermore, the bacterial inoculation had a positive impact on soil fertility by increasing enzymatic activity and microbial diversity compared to the control. The study highlights the role of bacterial inoculants in managing saffron crops. The findings demonstrated that microbial inoculants could enhance the nutraceutical qualities and yields of saffron, as well as improve soil biodiversity.