High nitrate supply reduces growth in maize, from cell to whole plant

• Published in: Journal of plant physiology Vol. 173; pp. 120 - 129
• Main Authors: Saiz-Fernández, Iñigo, De Diego, Nuria, Sampedro, Maria Carmen, Mena-Petite, Amaia, Ortiz-Barredo, Amaia, Lacuesta, Maite
• Format: Journal Article
• Language: English
• Published: Germany Elsevier GmbH 15-01-2015
• Subjects: 1-Aminocyclopropane-1-carboxylic acid; Alterations; Amino Acids, Cyclic - metabolism; Biomass; Cytokinins; Cytokinins - metabolism; Dominance; Ethylene; Maize; Nitrate; Nitrates; Nitrates - pharmacology; Nitrogen - metabolism; Ontogeny; Phytomer; Plant Epidermis - cytology; Plant Epidermis - drug effects; Plant Epidermis - growth & development; Plant Leaves - cytology; Plant Leaves - drug effects; Plant Leaves - growth & development; Plant Roots - cytology; Plant Roots - drug effects; Plant Roots - growth & development; Plant Shoots - cytology; Plant Shoots - drug effects; Plant Shoots - growth & development; Plants (organisms); Productivity; Reduction; Roots; Zea mays - cytology; Zea mays - drug effects; Zea mays - growth & development; Cytokinins; Phytomer; Ontogeny; Nitrate; 1-Aminocyclopropane-1-carboxylic acid
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1016/j.jplph.2014.06.018

Nitrogen (N) is an essential macronutrient that limits agricultural productivity, and both low and high N supply have been suggested to alter plant growth. The overall aim of this work is to study the impact of nitrate (NO3−) in maize yield and the possible causes that induce this alteration.
High NO3− doses did not increase the yield of maize grown neither in the field nor under controlled conditions. In fact, plants grown under controlled conditions for 45 days with NO3− concentrations over 5mM showed a decrease in biomass production. This reduction was perceptible in shoots prior to roots, where phytomer expansion was reduced. Cell size and number were also reduced in the leaves of plants with high NO3−. This alteration was correlated with the increase of 1-aminocyclopropane-1-carboxylic acid in leaves, which was probably translocated from the roots in order to synthesize ethylene. Cytokinins (CKs) also showed a relevant role in this inhibitory effect, increasing in high NO3− plants with a reduction in root and shoot growth, inhibition of apical dominance and a strong decrease of leaf expansion, symptoms described previously as “CK syndrome”. We propose that high NO3− inhibits maize growth by causing hormonal alterations that modify plant growth from cell to whole plant.