Yield variation in organic winter wheat: a diagnostic study in the Southeast of France

Issue		Agron. Sustain. Dev. Volume 25, Number 2, April-June 2005


Page(s)		213 - 223
DOI		10.1051/agro:2005016

Agron. Sustain. Dev. 25 (2005) 213-223
DOI: 10.1051/agro:2005016

Yield variation in organic winter wheat: a diagnostic study in the Southeast of France

Christophe David^a, Marie-Hélène Jeuffroy^b, John Henning^c and Jean-Marc Meynard^d

^a ISARA Lyon, 69288 Lyon Cedex 02, France
^b UMR d'Agronomie INRA-INA PG, BP 01, 78850 Thiverval Grignon, France
^c McGill University, Department of Agricultural Economics, 211 Lakeshore, Sainte-Anne de Bellevue, QC, Canada H9X 3V9
^d INRA SAD, BP 01, 78 850 Thiverval Grignon, France

(Accepted 18 January 2005)

Abstract - A diagnostic method for assessing regional variations in yield was implemented for a network of 24 organic wheat fields located in two neighboring regions, Diois and Val de Drôme (France). We studied: yield and its components; field environmental conditions of the fields; relations between indicators of potential limiting factors and yield components; and linkages between crop management and yield-limiting factors. The yield performances were low and variable (3.5 ± 1.4 t·ha^-1). The relative kernel number (RKN) was significantly related to nitrogen nutrition and weed density at flowering. The nitrogen nutrition index (NNIf) had a strong and positive effect on relative kernel number, while weed density (1/WF) had a negative effect. The percentage of kernel number variation explained by the regression model (RKN = 0.112 + 0.609 × NNIf + 0.2 × 1/WF) was adequate (Adj. R² = 0.53) with a RMSE of 0.09. The duration of the period of grain filling, reflected in the temperature sum, had a strong and positive effect on relative kernel weight (RTKW), while soil compaction and high temperature had a negative influence. Adjusted R²for the model was 0.42 with a RMSE of 0.16. The results confirm that legumes preceding crops improve nitrogen nutrition on subsequent winter wheat, e.g. the Nitrogen Nutrition Index at flowering (NNIf) = 0.51 ± 0.12 for a crop rotation with a rate of legumes over 37% vs. 0.41 ± 0.11 for a crop rotation with a rate of legumes under 25%. Alfalfa preceding crops significantly limited the weed density at harvest while stony soils and early sowing (before November 1st) enhanced weed density.

Key words: organic farming / winter wheat / yield / limiting factors / diagnostic method

Corresponding author: Christophe David davidc@isara.fr

© INRA, EDP Sciences 2005

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.