The invention relates to combine harvesters for harvesting seed and grain crops by magnetically treating the freshly threshed seeds in order to alter their biophysical, biochemical and physicochemicl parameters, and can be used in agriculture to magnetize the seeds of different types of crops during combine harvesting.The combine harvester for harvesting seed and grain crops comprising the following, arranged in succession in accordance with the technical process: a header, an inclined chamber, a threshing and separating device and a series of transporting members (a grain auger, distributing augers, elevators, etc.) from the thresher to the grain hopper, has a modular design of the transporting work members wherein each module body is provided with a magnetic field device for acting on a portion of freshly threshed seeds transported from the threshing and separating device to the grain hopper of the combine harvester in a continuous mode. Herein at least one module is provided with a magnetic field device. Furthermore, to increase the germinating ability of seeds and the yield of plants the device is provided with optimum magnetic field parameters specially selected for each specific type of crop and for each individual portion of freshly threshed seeds (be it of a type or even a variety of one and the same type) in the modules for suppression of biological processes, particularly the germinating ability which affects the change of the ripening times of crops for activation of biological processes, particularly the germinating ability which affects the quality of crops for activation of biological processes, particularly the germinating ability which affects their storage life without loss of quality, and other processes.