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Yield variation in organic winter wheat: a diagnostic study in the Southeast of France
C. David1*, M.-H. Jeuffroy2, J. Henning3 and J.-M. Meynard4
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
R2 for 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.
Source
Agronomy for Sustainable Development (2005) 25: 213-223
DOI: 10.1051/agro:2005016
Author Locations & Affiliations
(1) ISARA Lyon, 69288 Lyon Cedex 02, France
(2) UMR d'Agronomie INRA-INA PG, BP 01, 78850
Thiverval Grignon, France
(3) McGill University, Department of Agricultural
Economics, 211 Lakeshore, Sainte-Anne de Bellevue, QC, Canada H9X 3V9
(4) INRA SAD, BP 01, 78 850 Thiverval Grignon,
France
* Corresponding author, E-mail davidc@isara.fr
en français