AMF Inoculation in Pot : Saffron corms with horizontal diameters of 1.3 to 2.8 cm were sown in pots (4 L; 1 corm per pot) in the last ten days of August 2016. Pots were filled with sterile quartz sand (3 L per pot) on a layer of sterilized expanded clay (1 L per pot). Corms were treated with two inocula (MycAgro Lab, Breteniere, FR), one composed of a single fungus Rhizophagus intraradices (Ri) and one of R. intraradices and Funneliformis mosseae (Ri + Fm). Ten grams of each inoculum were placed under each corm in order to guarantee the contact between the inoculum and the roots and therefore to favor the symbiosis between AMF and roots. Saffron corms used as controls were not inoculated (AMF-). Corms were not treated against fungal pathogens. A randomized block design was used with a total of 48 pots displayed in two experimental plot units (24 pots per unit) and three treatments (8 pots per treatment). Cultivation lasted for one cycle (August 2016-April 2017) in a heated glasshouse of the Department of Agricultural Forest and Food Sciences (DISAFA) of the University of Torino (Italy, 45° 06′ 23.21″ N Lat, 7° 57′ 82.8″ E Long; 293 m a.s.l.), with an average temperature of 22 ℃ during the day and 16 ℃ in the night. Irrigation water (pH 7.4, EC 505 µS cm) was added weekly (250 mL per pot) with a drip system. The corms were fertilized by fertigation (VIGORFLOR, AL.FE. srl, MN, Italy) every two weeks starting from the emergence of the spate, in quantities of 1.5 g/L of water. No flowering occurred because of the small size of the corms.AMF Inoculation in Open Field : Saffron corms with horizontal diameters of 2.5 to 3.5 cm were planted in the last ten days of August 2016 in two Alpine experimental sites located in the municipality of Morgex (45° 45′ 35″ N; 7° 02′ 37.3″ E; 1000 m a.s.l.) and Saint Cristophe (45° 45′ 06″ N; 7° 20′ 37″ E; 700 m a.s.l.) in Italy and cultivation lasted for two cycles (2016-2017 and 2017-2018). Both sites were cultivated with saffron for at least the previous three years. Before starting the experiment both fields were milled. To assess the effects of AMF inocula on saffron cultivation and production, the same treatments used in the pot trial were applied (Ri, Ri + Fm or AMF-). A randomized block design was used, with three experimental plot units (blocks). Each plot unit consisted of 56 corms, planted in a 1.44 m² area (39 corms m^-2). Inter-row planting distance was of 7 cm, while between-row distance was 25 cm. Plots were separated from each other with at least 4 m distance. Before planting, 10 g of inoculum was placed under the corms to ensure contact between plant and the treatment. Irrigation was provided when needed and hand weeding control was conducted during cultivation, while no preplanting fertilization, tillage, or treatments against pathogens were applied. The two Alpine sites were characterized by semicontinental climate, with a long and cold winter . In general, both sites had a sandy-loam texture according to the USDA classification and similar chemical characteristics.

The inoculum composed by R. intraradices and F. mosseae was particularly effective in increasing flower production and saffron yield, while R. intraradices alone increased the content of some bioactive compounds-picrocrocin, quercitrin, crocin II-as well as antioxidant activity.