The exploitation of nitrate-tolerant symbiosis (nts) mutants of pulse legumes is limited by the accompanying supernodulation trait, which causes uncontrolled initiation of excessive symbiotic nodules on the root. The resulting disproportion between the photosynthetic capacity and the catabolic activity of nodules leads to growth deprivation, regardless of the desirable enhancement of symbiotic N fixation. Thanks to different priorities in the evaluation of forage crops like forage pea [Pisum sativum L. ssp. sativum var. arvense (L.) Poir.] in comparison with the pulse legumes, namely N accumulation and biomass production per crop area unit, the deleterious effect of supernodulation might be less perceived in the background of forage varieties. To test this assumption, the effect of the symbiotic mutation of line RisfixC was estimated after introgression into forage pea. Although growth deprivation persisted in a standard forage cultivar background, both the supernodulation and inferior growth were alleviated by as-yet unidentified modifiers present in the Zhodino E900 pea line. The prepared supernodulating/nts forage pea derivatives provide guidance for the development of a one-purpose legume variety with enhanced and stable symbiotic N accumulation.