Nitrogen Transfer Between Plants: A 15N Natural Abundance Study with Crop and Weed Species

• Published in: Plant and soil 2006-04, Vol.282 (1-2), p.7-20
• Main Authors: Moyer-Henry, K.A, Burton, J.W, Israel, D.W, Rufty, T.W
• Format: Article
• Language: English
• Subjects: Amaranthus palmeri; Arachis hypogaea; Crops; Cyperus esculentus; Experiments; Fertility; Genotypes; Glycine max; mycorrhizal fungi; Nitrogen; nitrogen fixation; nodulation; peanuts; plant biochemistry; plant nutrition; Senna obtusifolia; Sida spinosa; soil nutrients; Soybeans; stable isotopes; Weeds
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-005-3081-y

An increasing amount of evidence indicates that N can be transferred between plants. Nonetheless, a number of fundamental questions remain. A series of experiments was initiated in the field to examine N transfer between N2-fixing soybean (Glycine max [L.] Merr.) varieties and a non-nodulating soybean, and between N2-fixing peanut (Arachis hypogaea L.) or soybean and neighboring weed species. The experiments were conducted in soils with low N fertilities and used differences in N accumulation and/or 15N natural abundance to estimate N transfer. Mixtures of N2-fixing and non-nod soybean indicated that substantial inter-plant N transfer occurred. Amounts were variable, ranging from negligible levels to 48% of the N found in the non-nod at maturity. Transfer did not appear to strongly penalize the N2-fixing donor plants. But, in cases where high amounts of N were transferred, N content of donors was noticeably lowered. Differences were evident in the amount of N transferred from different N2-fixing donor genotypes. Results of experiments with N2-fixing crops and the weed species prickly sida (Sida spinosa L.) and sicklepod (Senna obtusifolia [L.] Irwin & Barneby) also indicated substantial N transfer occurred over a 60-day period, with amounts accounting for 30-80% of the N present in the weeds. Transfer of N, however, was generally very low in weed species that are known to be non-hosts for arbuscular mycorrhizae (yellow nutsedge, Cyperus esculentus L. and Palmer amaranth, Amaranthus palmeri [S.] Watson). The results are consistent with the view that N transfer occurs primarily through mycorrhizal hyphal networks, and they reveal that N transfer may be a contributing factor to weed problems in N2-fixing crops in low N fertility conditions.