In centers of origin, alfalfa (Medicago sativa L.) and wild relative populations have evolved to survive in highly diverse environments, with extremes that include the Arctic Circle, the desert areas of Kazakhstan and Western China, and the arid, Mediterranean areas of South Europe and North Africa. Alfalfa has further been disseminated anthropogenically, initially by ancient armies as a fodder source for horses, and in later European conquests to support emerging agriculture.

Selection of alfalfa accessions collected from environments with bioclimatic variables linked to extreme drought, heat, and cold tolerance. The subset includes alfalfa accessions originating from environments with an average monthly temperature range of -44–46ºC, 0–3,414 m elevation, up to 68.25ºN latitude and as low as 153 mm average annual precipitation (checked with satellite imagery to confirm no obvious supplementary water).

The M. sativa subsp. represented in the subset include 14 subsp. sativa, 4 nothosubsp. varia, 1 subsp. caerulea and 9 subsp. falcata. The subset also contains 2 M. sativa subsp. falcata accessions collected from the extreme mildest winter temperature for this sub species, where the minimum temperature of the coldest month was at least 3ºC.

• Humphries AW, Irish B, Peck DM, Webb J, and Julier B (2022) Utilizing Genesys to identify wild relatives of alfalfa with adaptation to diverse climates. World Alfalfa Congress, San Diego 12-19 November 2022.