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

• Published in: Journal of experimental botany Vol. 66; no. 7; pp. 2055 - 2065
• Main Authors: Zhan, Ai, Lynch, Jonathan P.
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.04.2015
• Subjects: Biomass; Nitrogen - metabolism; Phenotype; Photosynthesis; Plant Leaves - genetics; Plant Leaves - growth & development; Plant Leaves - metabolism; Plant Roots - genetics; Plant Roots - growth & development; Plant Roots - metabolism; Plant Shoots - genetics; Plant Shoots - growth & development; Plant Shoots - metabolism; RESEARCH PAPER; Soil - chemistry; Zea mays - genetics; Zea mays - growth & development; Zea mays - metabolism; Branching; maize (Zea mays); respiration; nitrogen (N); lateral root; frequency
• ISSN: 0022-0957; 1460-2431; 1460-2431
• DOI: 10.1093/jxb/erv007

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 the 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.