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Conservation agriculture cropping systems reduce blast disease in upland rice by affecting plant nitrogen nutrition

Dusserre Julie, Raveloson Harinjaka, Michellon Roger, Gozé Eric, Auzoux Sandrine, Sester Mathilde. 2017. Conservation agriculture cropping systems reduce blast disease in upland rice by affecting plant nitrogen nutrition. Field Crops Research, 204 : pp. 208-221.

Journal article ; Article de recherche ; Article de revue à facteur d'impact
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Quartile : Q1, Sujet : AGRONOMY

Abstract : In the central highlands of Madagascar, blast, a serious fungal disease of rice caused by Magnaporthe oryzae, was shown to be less severe in conservation agriculture (CA) than in conventional tillage (CT) cropping systems. To assess the effects of CA cropping systems on rice susceptibility to blast and to understand the mechanisms involved, an experiment was conducted over three growing seasons in two sites (at high and mid-altitude). Two fertilization treatments, one with mineral nitrogen (N) fertilizer, and one without, were studied in interaction with two different cropping systems (CA/CT) and two rice varieties that differ in their susceptibility to blast. The performances of the two cropping systems were assessed, and results showed that yields were no higher in the CA or were lower than in CT cropping systems. The effects of the treatments on upland rice crop growth were measured by leaf N content as an indicator of N crop status, and leaf area index (LAI) as an indicator of canopy density. In all years at both sites, leaf N content during early growth stages was higher in the CT than in the CA cropping system. The LAI was lower in the CA than in the CT cropping system at the high altitude site in all three years, and in two out of three seasons at the middle altitude site. Overall, when the level of blast was high, blast was less severe in the CA cropping system and with no N fertilizer. Leaf N content and LAI were used as intermediate explanatory variables in the statistical analyses, and one or the other or both always masked the effect of the cropping system or of N fertilization. Our results show that leaf N content during early growth stages masks the effect of the cropping system on leaf blast severity. When the LAI is strongly affected by the cropping system, it also masks the effect of the cropping system on the severity of leaf and panicle blast. Very often both variables masked the effects of the cropping system and of N fertilization. These findings should help improve disease management by modifying fertilization practices and crop nutrition in conservation agriculture cropping systems. (Résumé d'auteur)

Mots-clés Agrovoc : Oryza sativa, Riz pluvial, Magnaporthe grisea, Agriculture alternative, Nutrition des plantes, Système de culture, Fertilisation, Engrais azoté, Teneur en azote, Feuille, Région d'altitude, Variété, Rendement des cultures, Expérimentation au champ, Développement biologique, Non-travail du sol, Culture intercalaire, Zea mays, Glycine max, Vicia villosa, Cajanus cajan, Rotation culturale, Agroécosystème

Mots-clés géographiques Agrovoc : Madagascar

Mots-clés complémentaires : Agriculture de conservation

Mots-clés libres : Conservation agriculture, Upland rice, Blast disease, Magnaporthe oryzae, Leaf nitrogen content, Canopy density

Classification Agris : F08 - Cropping patterns and systems
H20 - Plant diseases
F04 - Fertilizing
F62 - Plant physiology - Growth and development

Champ stratégique Cirad : Axe 1 (2014-2018) - Agriculture écologiquement intensive

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Source : Cirad-Agritrop (https://agritrop.cirad.fr/583593/)

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