Maize with fewer nodal roots allocates mass to more lateral and deep roots that improve nitrogen uptake and shoot growth

Haichao Guo, Larry M. York

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

Abstract

Simulations indicated that reduced nodal root (NR) number (NRN) was promising for maize breeding, and were partially confirmed by relying on variation in NRN among inbreds. Using maize inbred line B73, experiments were conducted in hydroponics and tall mesocosms containing solid media with treatments involving no NR excision (0% NRE) or excising either 33% or 67% of the NRs as they emerged under high or low levels of nitrogen (N). Reduced NRN was hypothesized to increase elongation of all remaining root classes, N acquisition under low N, and shoot mass. Plants with 67% NRE had 12% and 19% less root mass fraction, 61% and 91% greater lateral to axial root length ratio regardless of N levels, and 61% and 182% greater biomass of embryonic roots under low N, compared with 0% NRE for hydroponics and mesocosms studies, respectively. Under low N in mesocosms, plants with 67% NRE had 52% greater shoot biomass, 450% greater root length at depth, and 232% greater deep-injected 15N content in the shoot relative to 0% NRE. These results reveal the mechanism by which plants with fewer NRs increase N capture and shoot mass by reallocation of biomass to lateral roots, embryonic roots, and first whorl NRs that increases foraging efficiency in solid media.

Original languageEnglish
Pages (from-to)5299-5309
Number of pages11
JournalJournal of Experimental Botany
Volume70
Issue number19
DOIs
StatePublished - Oct 15 2019
Externally publishedYes

Funding

This research was supported by the Noble Research Institute, LLC and the Samuel Roberts Noble Foundation (Cheaper Roots project). We thank Bryce Walker,Anand Seethepalli, and Na Ding for assistance with sampling and root scanning; and David Huhman and Bonnie Watson for their technical assistance in analyzing nitrogen content of samples.

Keywords

  • Adventitious roots
  • compensation
  • corn
  • nitrogen use efficiency
  • plant economy
  • shoot-borne roots

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