Erschienen in:
Agronomy Journal, 100 (2008) 2, Seite 271-276
Sprache:
Englisch
DOI:
10.2134/agronj2007.0059
ISSN:
0002-1962;
1435-0645
Entstehung:
Anmerkungen:
Beschreibung:
<jats:p>Plant‐based diagnostic methods of N nutrition require the critical N concentration (N<jats:sub>c</jats:sub>) to be defined, that is the minimum N concentration necessary to achieve maximum growth. A critical N curve (N<jats:sub>c</jats:sub> = 34.0<jats:italic>W</jats:italic><jats:sup>−0.37</jats:sup> with <jats:italic>W</jats:italic> being shoot biomass in Mg DM ha<jats:sup>−1</jats:sup>), based on whole plant N concentration, was determined for corn (<jats:italic>Zea mays</jats:italic> L.) in France. Our objectives were to validate this critical N curve in eastern Canada and to assess its plausibility to estimate the level of N nutrition in corn. Shoot biomass and N concentration were determined weekly during the growing season at three sites for 2 yr (2004 and 2005); four to seven N treatments were used at each site. Data points were divided into two groups representing either nonlimiting or limiting N conditions according to significant differences in shoot biomass at each sampling date. All data points included in the limiting N group were under the critical N curve and most data points of the nonlimiting N group were on or above the critical N curve, hence confirming the validity of the critical N curve determined in France. The nitrogen nutrition index (NNI), calculated as the measured N concentration divided by the predicted N<jats:sub>c</jats:sub>, ranged from 0.30 to 1.35. A significant relationship between relative grain yield (RY) and NNI (RY = −0.11 + 1.17 NNI if NNI < 0.93 and RY = 0.98 if NNI > 0.93; <jats:italic>R</jats:italic><jats:sup>2</jats:sup> = 0.89) was determined. The critical N curve from France is valid in eastern Canada and the NNI calculated from that curve is a reliable indicator of the level of N stress during the growing season of corn.</jats:p>