Effect of barley plant density on wild oat interference, shoot biomass and seed yield under zero tillage

115

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...

Section: Competitive Ability In Grain Cropsmentioning

confidence: 59%

“…1996;Champion et al 1998;Weiner et al 2001) and barley (O'Donovan et al 1999). Champion et al (1998) found that in wheat, this was true up to a certain density, after which no yield increases were seen.…”

Section: Breeding For Competitive Abilitymentioning

confidence: 99%

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

Mason¹,

Spaner²

2006

115

“…Increasing crop seeding rates was also shown to reduce weed competition and thus reduce weed seed production and its negative impact on yields of wheat (Carlson and Hill 1985) and barley (Evans et al 1991;Barton et al 1992;Kirkland 1993;O'Donovan et al 1999). Conceivably, selecting competitive cereal varieties and seeding them at relatively high seeding rates would contribute to the development of more economical and sustainable cropping systems by reducing dependence on herbicides for weed control.…”

Section: Mots Clés: Blé Roux Vitreux De Printemps (Brvp) Blé De Prinmentioning

confidence: 99%

Variable crop plant establishment contributes to differences in competitiveness with wild oat among cereal varieties

O’Donovan¹,

Blackshaw²,

Harker³

et al. 2005

R. 2005. Variable crop plant establishment contributes to differences in competitiveness with wild oat among wheat and barley varieties. Can. J. Plant Sci. 85: 771-776. Field experiments were conducted at three locations in Alberta to determine the relative competitiveness with wild oat (Avena fatua L.) of three hard red spring (HRS) and three Canada prairie spring (CPS) wheat (Triticum aestivum L.) varieties and a semidwarf hull-less barley (Hordeum vulgare L.) (Falcon), and normal height general purpose barley (AC Lacombe). Crop variety significantly affected crop yield loss, wild oat shoot dry weight and wild oat seed yield (competitive indicators). AC Lacombe barley was consistently more competitive than Falcon barley or any of the wheat varieties, while the HRS wheat varieties were mainly more competitive than the CPS varieties. Falcon barley was generally similar in competitiveness to the CPS wheat varieties. Differences among varieties in crop plant density at establishment correlated significantly with the competitive indicators suggesting that this factor contributed to the differences in competitiveness among the varieties. Crop density tended to be higher with the more competitive AC Lacombe barley and HRS wheat varieties than with the less competitive Falcon barley and CPS wheat varieties. Variety and seeding rate did not interact significantly but intentionally increasing the seeding rate improved the competitiveness of all varieties. . La variété a une incidence significative sur la réduc-tion du rendement, sur le poids sec des pousses de folle avoine et sur le rendement grainier de cette dernière (indicateurs de compétitivité). L'orge AC Lacombe est toujours plus compétitive que l'orge Falcon ou que les variétés de blé, mais les cultivars de BRVP sont passablement plus compétitifs que ceux de BPPC. L'orge Falcon est généralement aussi compétitive que les variétés de BPPC. La variation de la densité du peuplement à l'établissement de la culture présente une corrélation significative avec les indicateurs de compétitivité, signe que ce paramètre concourt aux différences de compétitivité entre les variétés. La densité du peuplement a tendance à être plus élevée chez l'orge AC Lacombe et chez les variétés de BRVP, plus compétitives, que chez l'orge Falcon et les variétés de BPPC, moins compétitives. La variété et la densité des semis n'interagissent pas de manière significative, mais l'accroissement délibéré de la densité des semis rehausse la compétitivité de toutes les variétés.

“…Crop density has also been shown to have a major influence on yield losses caused by weeds in barley (O'Donovan et al 1999), wheat (Carlson and Hill 1985) and canola (O'Donovan et al 1988(O'Donovan et al , 1989. Relationships between observed and estimated crop yield loss were generally superior in barley and canola when this function was included in the equations compared to weed density alone (Figs.…”

Section: Discussionmentioning

confidence: 92%

“…In later studies, more complex equations were developed to include the relative time of emergence of wild oat and crop (Cousens et al 1987) or crop density (O'Donovan et al 1999) in addi-tion to wild oat density. Regression equations were also developed for estimating canola yield losses due to volunteer barley (O'Donovan et al 1988) and wheat (O'Donovan et al 1989).…”

Section: Mots Clésmentioning

confidence: 99%

Field evaluation of regression equations to estimate crop yield losses due to weeds

O’Donovan¹,

Blackshaw²,

Harker³

et al. 2005

Self Cite

. 2005. Field evaluation of regression equations to estimate crop yield losses due to weeds. Can. J. Plant Sci. 85: 955-962. Various regression equations based on weed density alone, or relative time of weed and crop emergence or crop density in addition to weed density have been developed in western Canada to estimate the effects of wild oat (Avena fatua L.) and volunteer cereals on yield loss of field crops, and to advise farmers on the economics of weed control with herbicides. In , 1998, several of these equations were evaluated in 9 barley (Hordeum vulgare L.), 9 wheat (Triticum aestivum L.) and 11 canola (Brassica napus L.) fields in Alberta. Wild oat was the dominant weed in the barley and wheat fields, and wild oat or volunteer cereals in the canola fields. In barley and wheat, more complex equations based on both weed density and either crop density or relative time of weed and crop emergence were more reliable in estimating yield losses due to wild oat than those based on weed density alone. In canola, an equation based on volunteer barley and canola density provided the most reliable estimates. Under the assumed crop prices and herbicide costs, these equations also resulted in the best estimates of whether or not a herbicide application resulted in a net profit or loss. Herbicide application was rarely economical in barley, but usually economical in wheat and canola reflecting the different market value of the crops. The implementation of the weed economic threshold concept is likely to be more feasible in low-value crops such as feed barley than in higher-value crops such as canola. Dans l'ouest du Canada, on se sert d'équations de régression pour estimer l'incidence de la folle avoine (Avena fatua L.) et de la repousse spontanée des céréales sur le rendement des cultures d'après la densité de peuplement des adventices, la levée des mauvaises herbes et des cultures ou la densité de peuplement des adventices et de la culture, l'objectif étant de conseiller les agriculteurs sur le désherbage chimique. Les auteurs ont évalué plusieurs de ces équations dans 9 champs d'orge (Hordeum vulgare L.), 9 de blé (Triticum aestivum L.) et 11 de canola (Brassica napus L.) de l'Alberta en 1997, 1998 et 1999. La folle avoine était la principale adventice dans les champs d'orge et de blé alors que ceux de canola étaient surtout envahis par la folle avoine et les repousses spontanées de céréales. Dans les champs de blé et d'orge, les équations plus complexes, reposant à la fois sur la densité de peuplement des mauvaises herbes et sur celle de la culture ou sur la levée relative de l'adventice et de l'espèce cultivée sont plus fiables que les équations se fondant uniquement sur la densité de peuplement de la mauvaise herbe pour estimer les pertes de rendement attribuables à la folle avoine. Dans les champs de canola, c'est l'équation reposant sur la densité des repousses spontanées d'orge et sur la densité du canola qui donne les estimations les plus sûres. Compte tenu du prix hypothétique de la culture et des herbicide...