The Influence of Seed-borne N in¹⁵N Isotope Dilution Studies with Legumes

Abstract

Abstract The distribution of seed-borne N in shoot and root of pea and field bean was studied using three methods: 1) determination of the N content in shoot and root of plants grown in sand culture without other N sources, 2) 15N isotope dilution in plants grown in Rhizobium-free medium supplied with 15N-labelled nitrate and 3) determination of the 15N-enrichment in shoot and root of plants in which the seed-borne N was labelled with 15N. The results from the three methods were concordant, showing that from 44 to 50% of the seed-borne N in the two species was located in above-ground plant parts. The effect of corrections for seed-borne N in studies of nitrogen fixation in legumes is discussed.