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Reduced frequency of lateral root branching improves N capture from low N soils in maize

Authors:

Zhan, A; Lynch, JP

Source:

J Experimental Botany, Feb 2015

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Open-Access Full Text:

http://jxb.oxfordjournals.org/cgi/content/full/erv007?ijkey=M7iIdNV1tTezzae&keytype=ref

Abstract:


Suboptimal nitrogen (N) availability is a primary constraint for crop production in developing countries, while in developed countries, intensive N fertilization is a primary economic, energy, and environmental cost for crop production. We tested the hypothesis that under low N conditions, maize (Zea mays) lines with few but long (FL) lateral roots would have greater axial root elongation, deeper rooting, and greater N acquisition than lines with many but short (MS) lateral roots. Maize recombinant inbred lines contrasting in lateral root number and length were grown with adequate and suboptimal N in greenhouse mesocosms and in the field in the USA and South Africa (SA). In low N mesocosms the FL phenotype had substantially reduced root respiration and greater rooting depth than the MS phenotype. In low N fields in the USA and SA the FL phenotype had greater rooting depth, shoot N content, leaf photosynthesis, and shoot biomass than MS phenotype. The FL phenotype yielded 31.5% more than the MS phenotype under low N in the USA. Our results are consistent with the hypothesis that sparse but long lateral roots improve N capture from low N soils. These results with maize probably pertain to other species. The FL lateral root phenotype merits consideration as a selection target for greater crop N efficiency.

Keywords: Branching, frequency, lateral root, maize, nitrogen, respiration