Abstract
ABSTRACT: Consecutive application of herbicides has led to the evolution of herbicide-resistant weeds. This resistance is often associated with a fitness cost. Hence, a completely randomized design experiment with three replications was conducted to evaluate the fitness cost of haloxyfop-R methyl ester resistant winter wild oat biotypes (Avena ludoviciana Durieu) possessing Ile-2041-Asn mutation compared to susceptible ones. The pre-germinated F2 generation winter wild oat biotypes were sown in 0.2 m2 pots containing 50 cm of silty-loam soil outdoors and their growth parameters including tiller number, plant height, leaves per plant, leaf area per plant, chlorophyll content index, leaf dry weight, and plant dry weight were measured 30, 70, 100, 115 and 130 days after planting. Leaf area index, leaf area ratio, specific leaf area, relative growth rate, net assimilation rate, and crop growth rate were also calculated. Seed production, 1000 kernel weight, and flag leaf area were measured at the end of the growth period. According to the results, no fitness cost was observed between susceptible and resistant biotypes, indicating that susceptible biotypes may not overcome resistant ones in the field. Although imposing a new selective pressure via application of an herbicide possessing a different mode of action may control both susceptible and resistant biotypes, herbicide rotation must be adapted to impede the evolution of further resistance. Also, the same non-chemical weed management methods such as careful selection of sowing date can be implemented to ameliorate adverse effects of this weed on crop production.
Highlights
Weeds are undesired plants which are considered from the very dawn of agriculture as pests (Powles and Yu, 2010)
The reasons behind occurrence of fitness cost resulted by resistant alleles include: 1) mutations in the enzymeencoding herbicide target leading to resistance may interfere with plant metabolism and function (Vila-Aiub et al, 2009); 2) Herbicide resistant may result in the diversion of resources from growth and propagation to defense (Coley et al, 1985); 3) Pleiotropic effects resulted by resistant alleles might alter ecological relations, e.g. these effects may render the plant less attractive for pollinators (Purrington, 2000; Strauss et al, 2002)
1000 kernel weight, and flag leaf area were measured at the end of the experiment period, and their data were analyzed as a completely randomized design (CRD) with three replication using SAS software ver. 9 and the means were compared via the LSD method at p
Summary
ABSTRACT - Consecutive application of herbicides has led to the evolution of herbicide-resistant weeds This resistance is often associated with a fitness cost. A completely randomized design experiment with three replications was conducted to evaluate the fitness cost of haloxyfop-R methyl ester resistant winter wild oat biotypes (Avena ludoviciana Durieu) possessing Ile-2041-Asn mutation compared to susceptible ones. Um delineamento inteiramente casualizado com três repetições foi conduzido para avaliar o custo de adoção dos biótipos de aveia selvagem de inverno resistentes ao haloxyfop-R methyl ester (Avena ludoviciana Durieu) com a mutação Ile-2041-Asn, em comparação com os suscetíveis. Embora a imposição de nova pressão seletiva via aplicação de um herbicida com modo de ação diferente possa controlar biótipos suscetíveis e resistentes, a rotação do herbicida deve ser adaptada a fim de impedir maior evolução da resistência. Palavras-chave: Avena ludoviciana Durieu, índices de crescimento, efeitos pleiotrópicos, Ile-2041-Asn
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