Nitrogen acquisition, fixation and transfer in maize/alfalfa intercrops are increased through root contact and morphological responses to interspecies competition

• Published in: Journal of Integrative Agriculture Vol. 20; no. 8; pp. 2240 - 2254
• Main Authors: SHAO, Ze-qiang, ZHENG, Cong-cong, POSTMA, Johannes A., LU, Wen-long, GAO, Qiang, GAO, Ying-zhi, ZHANG, Jin-jing
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2021; College of Resource and Environment Engineering,Jilin Institute of Chemical Technology,Jilin 132022,P.R.China%Forschungszentrum Jülich GmbH,Institute of Bio-and Geosciences-Plant Sciences(IBG-2),Jülich 52428,Germany%College of Resource and Environment Engineering,Jilin Institute of Chemical Technology,Jilin 132022,P.R.China%College of Resources and Environmental Sciences,Jilin Agricultural University/Key Laboratory of Sustainable Utilization of Soil Resources in the Commodity Grain Bases in Jilin Province,Changchun 130118,P.R.China%Key Laboratory of Vegetation Ecology,Northeast Normal University,Changchun 130024,P.R.China; College of Resources and Environmental Sciences,Jilin Agricultural University/Key Laboratory of Sustainable Utilization of Soil Resources in the Commodity Grain Bases in Jilin Province,Changchun 130118,P.R.China; KeAi Communications Co., Ltd
• Subjects: agriculture; alfalfa; biomass production; corn; greenhouse experimentation; lateral roots; leaves; maize/alfalfa intercropping; nitrogen; nitrogen fixation; nitrogen fixation and transfer; nitrogen utilization; nutrient use efficiency; nylon; root morphology; total nitrogen; nitrogen utilization; nitrogen fixation and transfer; maize/alfalfa intercropping; root morphology
• ISSN: 2095-3119; 2352-3425
• DOI: 10.1016/S2095-3119(20)63330-5

Nitrogen (N) fixation by legumes and nitrogen transfer to cereals have been considered as important pathways for overyielding and higher N use efficiency in cereal/legume intercropping systems. However, the extent to which root morphology contributes to N fixation and transfer is unclear. A two-factorial greenhouse experiment was conducted to quantify the N fixation, transfer and root morphology characteristics of the maize/alfalfa intercropping system in two consecutive years using the 15N-urea leaf labeling method, and combining two N levels with three root separation techniques. N application could inhibit N fixation and transfer in a maize/alfalfa intercropping system. Irrespective of the N application level, compared with plastic sheet separation (PSS), no separation (NS) and nylon mesh separation (NNS) significantly increased the total biomass (36%) and total N content (28%), while the N fixation rate also sharply increased by 75 to 134%, and the amount of N transferred with no root barrier was 1.24–1.42 times greater than that with a mesh barrier. Redundancy analysis (RDA) showed that the crown root dry weight (CRDW) of maize and lateral root number (LRN) of alfalfa showed the strongest associations with N fixation and transfer. Our results highlight the importance of root contact for the enhancement of N fixation and transfer via changes in root morphology in maize/alfalfa intercropping systems, and the overyielding system was achieved via increases in maize growth, at the cost of smaller decreases in alfalfa biomass production.