Incremental crop tolerance to weeds: A measure for selecting competitive ability in Australian wheats

Abstract

Total reliance on herbicides for weed control is unsustainable with the spread of herbicide resistance and the environmental need to reduce pesticide use. Strongly competitive wheat crops that have high tolerance to weed pressure and therefore maintain high yields in the presence of weeds are a low-cost option for reducing dependence on herbicides. We examined the feasibility of selecting for wheat tolerance to weeds by crossing varieties differing for traits associated with competitiveness. Competitive ability and yield potential must be treated as separate traits for selection. Current measures of crop tolerance to weed competition do not separate the two traits so that selection based on these measures is often synonymous with selection for yield potential rather than pure tolerance. We propose a new measure, termed Incremental Crop Tolerance (ICT) that reflects the incremental yield difference between genotypes associated with tolerance, over and above differences in underlying yield potential.

Uso associado e contribuições relativas de genótipos de aveia e de práticas de manejo à competitividade da cultura com plantas concorrentes

“…Uso associado e contribuições relativas de genótipos de ... Em trigo, cultivares competitivos que apresentam elevada tolerância à pressão das plantas daninhas e, dessa forma, mantêm produtividade elevada na presença destas constituem-se em opção de baixo custo para reduzir a dependência aos herbicidas do cereal (Lemerle et al, 2006). O cultivar de aveia UPF 16, nas condições em que foi realizada a pesquisa, revelou elevado potencial no manejo cultural e integrado de plantas daninhas.…”

Differences between organically grown varieties of spring wheat, in response to weed competition and yield

“…Strongly competitive wheat crops that have a high tolerance to weed pressure and maintain high yields in the presence of weeds, are a lowcost option for weed management in organic agriculture and can reduce the dependence on herbicides in lowinput systems (Lemerle et al 2006). The lack of information on the relative performance of cereal crops and their modern varieties, under organic conditions, is a limitation for farmers (Tamm et al 2009).…”

“…Morphological traits associated with wheat competitiveness are tiller number, height, and early vigour, but not one set of characteristics makes wheat plants competitive in all situations (Christensen 1995;Seavers and Wright 1999;Lemerle et al 2006;Watson et al 2006). The competitive ability of wheat could be improved by choosing from available varieties or by breeding for competitiveness.…”

Características morfológicas em plantas de cultivares de aveia como indicadoras do potencial competitivo com plantas daninhas

“…Devido ao rápido surgimento de casos de resistência de plantas daninhas aos herbicidas, a habilidade competitiva pode se tornar um critério ainda mais importante para a seleção de novas cultivares em relação àquelas priorizadas anteriormente em programas de melhoramento de plantas (LEMERLE et al, 2006). No contexto atual da agricultura, conhecer melhor as características de desenvolvimento inicial de cultivares de aveia que possam se associar à habilidade competitiva, a exemplo do que já ocorre com outras culturas anuais, é importante para acrescentar novas estratégias ao manejo integrado de plantas daninhas.…”