Study the Non-Target Site Based Mechanisms of Resistance in Aryloxyphenoxy Propionate Resistant-Phalaris Minor Retz. Biotypes

Acetyl co-enzyme A carboxylase inhibitors are commonly used for post emergence control of grass weeds in broad leaf crops. Some of these herbicides are applied to control grass weeds in wheat and barley fields. Recently some aryloxyphenoxy propionate-resistant Phalaris minor Retz. populations that have developed the resistance to diclofop methyl, fenoxaprop-P butyl and clodinafop propargyl, have been detected in wheat fields of Fars where these graminicides had been applied for several years. Previous biochemical studies revealed that mechanism of resistance in SR3, MR4 and AR biotypes is due to presence of an herbicide-resistant ACCase enzyme in the biotypes. There was not significant difference between susceptibility of ACCase enzyme of other resistant biotypes (FR2, FR3, FR4, FR5, FR6, FR8, MR1, MR2, ER1, ER2 and GR2-1) and susceptible one (ES). In order to study the non-target site based mechanism(s) of resistance to diclofop methyl in two resistant Phalaris minor Retz. biotypes, some experiments were conducted to investigate retention, absorption, translocation and metabolism of diclofop methyl in the resistant (SR3 and FR8) and susceptible (ES) biotypes in Agro – Biochemistry Laboratory of Córdoba University, Spain, during 2008. The amount of herbicide retention and absorption did not differ among resistant and susceptible biotypes. Almost all of the absorbed herbicide remained in the treated leaf and only a little bit of diclofop methyl was translocated to other parts of the treated plants in both resistant and susceptible biotypes. The results of this study showed that there was not difference in retention, absorption, translocation and metabolism of diclofop methyl between FR8 and susceptible one; suggesting unknown mechanism of resistance may be involved in FR8 plants