Comparing Fitness Cost Associated with Haloxyfop-R Methyl Ester Resistance in Winter Wild Oat Biotypes

Abstract

<jats:p>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.</jats:p>

Effect of Herbicides on Forage Dry Matter Yield and Plant Density in the Old Arable Lands in Communal Area of the Eastern Cape Province, South Africa

“…Likewise, HBE significantly reduced the DM yield during the first year. In agreement, [19] found that HBE controls a broad range of annual grasses. Furthermore, contrary to other broadleaf herbicides, HBE herbicides also control grassy weeds and have a direct effect on pasture legumes [20].…”

Herbicide Resistance in Phalaris Species: A Review

“…The fitness cost imposed by herbicide resistance may be quantified by measuring various characteristics of the species, including germination [83], phenology, vegetative characteristics, fecundity, and yield [90]. Conversely, herbicide resistance may impose no fitness cost on the species [91,92]. Furthermore, the mutation responsible for resistance may even lead to positive [93] effects on the growth and reproduction of the species.…”