Carbon costs of dinitrogen fixation associated with dry matter accumulation in alfalfa

Dinitrogen fixation of nodulated legumes theoretically may limit crop yield because of nodule needs for products of photosynthesis; however, this concept is poorly supported by experimental evidence. To determine how nodule C use might limit legume dry-matter accumulation, the C costs of N 2 fixation of alfalfa (Medicago sativa L.) were investigated in the glasshouse during two harvest-regrowth cycles