Insufficient nitrogen supply from symbiotic fixation reduces seasonal crop growth and nitrogen mobilization to seed in highly productive soybean crops

Nicolas Cafaro La Menza, Juan Pablo Monzon, John L. Lindquist, Timothy J. Arkebauer, Johannes M.H. Knops, Murray Unkovich, James E. Specht, Patricio Grassini

Research output: Contribution to journalArticlepeer-review

Abstract

Nitrogen (N) supply can limit the yields of soybean [Glycine max (L.) Merr.] in highly productive environments. To explore the physiological mechanisms underlying this limitation, seasonal changes in N dynamics, aboveground dry matter (ADM) accumulation, leaf area index (LAI) and fraction of absorbed radiation (fAPAR) were compared in crops relying only on biological N2 fixation and available soil N (zero-N treatment) versus crops receiving N fertilizer (full-N treatment). Experiments were conducted in seven high-yield environments without water limitation, where crops received optimal management. In the zero-N treatment, biological N2 fixation was not sufficient to meet the N demand of the growing crop from early in the season up to beginning of seed filling. As a result, crop LAI, growth, N accumulation, radiation-use efficiency and fAPAR were consistently higher in the full-N than in the zero-N treatment, leading to improved seed set and yield. Similarly, plants in the full-N treatment had heavier seeds with higher N concentration because of greater N mobilization from vegetative organs to seeds. Future yield gains in high-yield soybean production systems will require an increase in biological N2 fixation, greater supply of N from soil or fertilizer, or alleviation of the trade-off between these two sources of N in order to meet the plant demand.

Original languageEnglish (US)
Pages (from-to)1958-1972
Number of pages15
JournalPlant Cell and Environment
Volume43
Issue number8
DOIs
StatePublished - Aug 1 2020

Keywords

  • Glycine max (L.) Merr.
  • leaf area
  • nitrogen
  • soybean
  • symbiotic fixation

ASJC Scopus subject areas

  • Physiology
  • Plant Science

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