Use of a ^sup 15^N2 labelling technique to estimate exudation by white clover and transfer to companion ryegrass of symbiotically fixed N

• Published in: Plant and soil Vol. 369; no. 1-2; p. 187
• Main Authors: Lesuffleur, F, Salon, C, Jeudy, C, Cliquet, J B
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01-08-2013
• Subjects: Ammonium; Biogeochemistry; Grasses; Legumes; Nitrogen; Soils
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-012-1562-3

N rhizodeposition by legumes leads to enrichment of N in soils and in companion plants. N rhizodeposition can be divided into two major components, root exudation and root senescence. Our aim was to quantify N root exudation in white clover (Trifolium repens L.) through an estimation of short-term N rhizodeposition and to assess its impact on N transfer to companion perennial ryegrass (Lolium perenne L.) grown in mixture with clover. ^sup 15^N2 provided in the root atmosphere for 3 days was used to estimate transfer of symbiotically fixed nitrogen (SFN) to the growing medium by clover grown in pure stand and to ryegrass by clover grown in mixture for 2 months. The proportion of N rhizodeposited over the 3 days increased from 3.5 % of SFN in pure stand to 5.3 % in mixture. The ^sup 15^N-enrichment of ammonium from the adhering substrate shows that a part of the rhizodeposited N was released in the form of ammonium. 4 % of the rhizodeposited N was taken up by ryegrass during the labelling period. This study showed a significant contribution of root N exudation to the total N rhizodeposition of legumes and in the transfer of N to grasses.[PUBLICATION ABSTRACT]