Abstract
Sterile wild oat (Avena sterilis L.) is an autogamous grass established in warm climate regions. This species has been used as a cover crop in Mediterranean perennial crops during the spring period prior to initiating competition with the main crop for water and nutrients. However, such cover crops need to be controlled (by glyphosate or tillage) before the beginning of summer period (due to the possibility of intense drought stress). In 2011, the olive grove farmers of southern Spain expressed dissatisfaction because of the ineffective control with glyphosate on A. sterilis. Experiments were conducted to determine whether the continued use of glyphosate over a 5 year period had selected a new resistant or tolerant species. The GR50 values obtained for A. sterilis were 297.12 and 245.23 g ae ha−1 for exposed (E) and un-exposed (UE) glyphosate accessions, respectively. The spray retention and shikimic acid accumulation exhibited a non-significant difference between the two accessions. The results of 14C- glyphosate absorption was the same in the two accessions (E and UE), while the translocation from the treated leaf to the rest of the shoots and roots was similar in A. sterilis accessions. Glyphosate metabolism to aminomethylphosphonic acid (AMPA) and glyoxylate was similar in both accessions, but increased after treatment with glyphosate, indicating that metabolism plays an important role in tolerance. Both A. sterilis accessions, present similarity in the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) activity enzyme with different glyphosate concentrations and without glyphosate, confirming that both accessions present the same genomic characteristics. The above-mentioned results indicate that innate tolerance to glyphosate in A. sterilis is probably and partly due to reduced herbicide absorption and translocation and metabolism compared to the susceptibility of other grasses weeds like Chloris inflata, Eleusine indica, and Lolium rigidum.
Highlights
Wild oats are known as Avena fatua L. or various subspecies of A. sterilis L
Dose-response assays of 23 accessions (E, and UE01 to UE22) of A. sterilis resulted to similar GR50 values for all accessions
Less than 55% of glyphosate in relation to its metabolites (AMPA, glyoxylate and sarcosine) was detected in both accessions of A. sterilis (Table 3). These results show that the mechanism of the metabolism is involved in the innate tolerance of A. sterilis to glyphosate
Summary
Wild oats are known as Avena fatua L. or various subspecies of A. sterilis L. The best known subspecies are A. ludoviciana Dur. Sterilis, known as A. macrocarpa Moench) (Chancellor, 1976). A. sterilis is an autogamous grass species, and its isolated populations can produce seeds. In the absence of competition, this weed is characterized by enormous seed production of more than 400 seeds per plant. A. fatua is typical of temperate regions of northwestern Europe, North America, South America (Argentina and Uruguay), Australia, and South Africa. The subspecies of A. sterilis have been mostly established in Mediterranean climate regions, such as southern Europe, and North Africa (Travlos and Giannopolitis, 2010)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
