The article will focus on the mutagenesis programme in agriculture implemented by the Italian Atomic Energy Commission, starting from 1955, through the establishment of a specific technological and experimental system: the so-called “gamma field”, a piece of agricultural land with a radioisotope of Cobalt-60 at the centre. The Cobalt-60 would emit constant radiation, which would bombard the specimens planted in concentric circles around the source, inducing genetic mutations. The Italian gamma field went into operation in January 1960 at the Casaccia Laboratory, about twenty miles north of Rome, with a radiation device made available by the US Government for the Atoms for Peace programme This article will analyse, first of all, how the American experimental model of mutation breeding was translated into the Italian context, becoming instrumental for the establishment of plant genetics within the local academic system; secondly, it will describe how the sociotechnical imaginary embodied by the gamma field was part and parcel of this process of disciplinebuilding and scientific demarcation.