The critical weed‐free period in organically‐grown winter wheat

Welsh, J. P.; Bulson, H. A. J.; Stopes, C.; Froud-Williams, R. J.; Murdoch, A. J.

doi:10.1111/j.1744-7348.1999.tb05270.x

Cited by 32 publications

(19 citation statements)

References 5 publications

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“…This suggests that the critical period of competition for the crop occurred very early in the crop cycle, essentially before winter. Welsh et al (1999) confirmed that the control of weed emergence in organic wheat crops was the most important at the beginning of the crop cycle.…”

Section: Weed Competition and Nitrogenmentioning

confidence: 53%

Diagnosis of limiting factors of organic oilseed rape yield. A survey of farmers’ fields

Valantin‐Morison

2008

Agron. Sustain. Dev.

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Diagnosis of limiting factors of organic oilseed rape yield. A survey of farmers' fieldsMuriel Valantin-Morison, J.M. Meynard To cite this version: Muriel Valantin-Morison, J.M. Meynard. Diagnosis of limiting factors of organic oilseed rape yield. A survey of farmers' fields. Agronomy for Sustainable Development, Springer Verlag/EDP Sci-Abstract -The yield of organic winter oilseed rape (WOSR) crop is low and variable in organic farming, but the reasons responsible for this problem are not clear. Aiming to identify the factors affecting organic oilseed rape yields, we carried out a diagnostic study on a network of 19 farmers' fields in four contrasting regions of France over a two-year period. Weed density and biomass, nitrogen absorption by the crop and by weeds, and nutrient availability in the soil, as well as the occurrence of pests and diseases, were assessed at four developmental stages. A range of possible limiting factors throughout the crop cycle led us to use a regression procedure for different periods, using the yield components during spring and biomass during autumn as dependent variables. We identified factors limiting yield and the critical time points at which they acted, which has never been done. Yield variation was strongly correlated with number of grains.m −2 . Dry biomass of weeds, nitrogen uptake by weeds and density of weeds appeared to explain 39% of variation in crop biomass in early winter, while pollen beetle and rape stem weevil damage explained 4.5% and 12% of variation in the number of flowers.m −2 and the number of branches.m −2 , respectively. Crop nitrogen deficiencies occurring before branching were strongly correlated with weed biomass in flowering. Analysis of covariance showed that sowing date, soil management and the quantity of organic manure application may have significantly affected the nitrogen nutrition index, nitrogen uptake by plants and ratio of weed biomass: a late sowing date and shallow soil tillage were related to a low crop nitrogen nutrition index and high ratio of weed biomass. From a practical point of view, this study demonstrated that it should be possible to reduce weed competition by ensuring that the amount of nitrogen in soil before sowing is around 100 kg/ha. winter oilseed rape / organic farming / yield variability / yield components / diagnosis / farmers' fields / nitrogen deficiencies / weed competitio * Corresponding authors: morison@grignon.inra.fr, meynard@grignon.inra.fr Article published by EDP Sciences and ava...

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Section: Weed Competition and Nitrogenmentioning

confidence: 53%

Diagnosis of limiting factors of organic oilseed rape yield. A survey of farmers’ fields

Valantin‐Morison

2008

Agron. Sustain. Dev.

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“…The same relationship has been observed in the number of kernels per spike (Satorre and Snaydon 1992; Das and Yaduraju 1999;Welsh et al 1999). In many studies, the effect of weed interference on kernel weight in wheat has been non-significant (Satorre and Snaydon 1992;Hucl 1998;Das and Yaduraju 1999;Welsh et al 1999). Satorre and Snaydon (1992) reported similar results for the yield components of wheat, oat and barley under competition from Avena fatua L.; however, O'Donovan et al (1999) reported that competition from A. fatua L. caused marginal decreases in the kernel weight of barley.…”

Section: Competitive Ability In Grain Cropsmentioning

confidence: 56%

“…In wheat, the number of fertile tillers per unit area has been found to decrease with increased weed pressure (Kirkland and Hunter 1991;Satorre and Snaydon 1992;Huel and Hucl 1996;Das and Yaduraju 1999;Welsh et al 1999). The same relationship has been observed in the number of kernels per spike (Satorre and Snaydon 1992; Das and Yaduraju 1999;Welsh et al 1999). In many studies, the effect of weed interference on kernel weight in wheat has been non-significant (Satorre and Snaydon 1992;Hucl 1998;Das and Yaduraju 1999;Welsh et al 1999).…”

Section: Competitive Ability In Grain Cropsmentioning

confidence: 99%

Competitive ability of wheat in conventional and organic management systems: A review of the literature

Mason¹,

Spaner²

2006

Can. J. Plant Sci.

111

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Mason, H. E. and Spaner, D. 2006. Competitive ability of wheat in conventional and organic management systems: A review of the literature. Can. J. Plant Sci. 86: 333-343. Wheat (Triticum aestivum L.) is the world's most widely grown crop, cultivated in over 115 nations. Organic agriculture, a production system based on reducing external inputs in order to promote ecosystem health, can be defined as a system that prohibits the use of synthetic fertilizers, chemical pesticides and genetically modified organisms. Organic agriculture is increasing in popularity, with a 60% increase in the global acreage of organically managed land from the year 2000 to 2004. Constraints that may be associated with organic grain production include reduced yields due to soil nutrient deficiencies and competition from weeds. Global wheat breeding efforts over the past 50 yr have concentrated on improving yield and quality parameters; in Canada, disease resistance and grain quality have been major foci. Wheat varieties selected before the advent of chemical fertilizers and pesticides may perform differently in organic, low-input management systems than in conventional, high-input systems. Height, early-season growth, tillering capacity, and leaf area are plant traits that may confer competitive ability in wheat grown in organic systems. Wheat root characteristics may also affect competitive ability, especially in low-input systems, and more research in this area is needed. The identification of a competitive crop ideotype may assist wheat breeders in the development of competitive wheat varieties. Wheat varieties with superior performance in low-input systems, and/or increased competitive ability against weeds, could assist organic producers in overcoming some of the constraints associated with organic wheat production. Les contraintes associées à la production de céréales biologiques comprennent la baisse de rendement attribuable aux carences d'élé-ments nutritifs dans le sol et la concurrence des mauvaises herbes. Au cours des 90 dernières années, les efforts internationaux d'amélio-ration du blé se sont concentrés sur la hausse du rendement et les paramètres de qualité; au Canada, on s'est également beaucoup intéressé à la résistance aux maladies ainsi qu'à la qualité du grain. Cultivées de manière biologique, c'est-à-dire sans grand apport d'intrants, il se pourrait que les variétés de blé sélectionnées avant l'avènement des engrais et des pesticides chimiques donnent des résul-tats différents de ceux observés avec les systèmes agricoles usuels, nécessitant des intrants en abondance. La hauteur, la précocité, le tallage et la surface foliaire sont autant de caractéristiques susceptibles de conférer une plus grande compétitivité au blé dans les systèmes de production biologique. Les paramètres des racines pourraient aussi modifier la compétitivité, surtout lorsqu'on utilise peu d'intrants, et il faudrait intensifier les recherches dans ce domaine. L'identification d'un idéotype compétitif aiderait les phytogénéticiens à créer des cu...

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“…Critical period of weed control (CPWC) of some herbaceous field crops. [92] white bean Phaseolus vulgaris L. from the second-trifoliolate and first-flower stages of growth [93] winter wheat Triticum aestivum L. 506-1023 GDD [94] Note: DAE: day after emergence; GDD: growing degree days, calculated as ((T max + T min )/2 -T b ).…”

Section: Mechanical Controlmentioning

confidence: 99%

Integrated Weed Management in Herbaceous Field Crops

2020

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Current awareness about the environmental impact of intensive agriculture, mainly pesticides and herbicides, has driven the research community and the government institutions to program and develop new eco-friendly agronomic practices for pest control. In this scenario, integrated pest management and integrated weed management (IWM) have become mandatory. Weeds are commonly recognized as the most important biotic factor affecting crop production, especially in organic farming and low-input agriculture. In herbaceous field crops, comprising a wide diversity of plant species playing a significant economic importance, a compendium of the specific IWM systems is missing, that, on the contrary, have been developed for single species. The main goal of this review is to fill such gap by discussing the general principles and basic aspects of IWM to develop the most appropriate strategy for herbaceous field crops. In particular, a 4-step approach is proposed: (i) prevention, based on the management of the soil seedbank and the improvement of the crop competitiveness against weeds, (ii) weed mapping, aiming at knowing the biological and ecological characteristics of weeds present in the field, (iii) the decision-making process on the basis of the critical period of weed control and weed thresholds and iv) direct control (mechanical, physical, biological and chemical). Moreover, the last paragraph discusses and suggests possible integrations of allelopathic mechanisms in IWM systems.

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The critical weed‐free period in organically‐grown winter wheat

Cited by 32 publications

References 5 publications

Diagnosis of limiting factors of organic oilseed rape yield. A survey of farmers’ fields

Diagnosis of limiting factors of organic oilseed rape yield. A survey of farmers’ fields

Competitive ability of wheat in conventional and organic management systems: A review of the literature

Integrated Weed Management in Herbaceous Field Crops

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