Effect of clodinafop-propargyl application on membrane leakage, phenols and antioxidant enzymes in Phalaris minor

Abstract

Phalaris minor Retz. is a major weed of wheat crop in northern parts of India. Resistance of P. minor to clodinafop-propargyl - an AC Case inhibitor is widespread in northern India. A pot study was conducted to evaluate the effect of clodinafop-propargyl application on membrane leakage, phenols and antioxidant enzymes in two P. minor Retz. populations- one susceptible and other resistant to this herbicide. Clodinafop-propargyl resistant population exhibited no plant mortality at 2X dose of clodinafop but in susceptible population, there was significant reduction in plant density due to X and 2X doses of clodinafop. The membrane leakage increased with increase in clodinafop dose in susceptible and resistant P. minor populations. However, resistant P. minor population exhibited reduction in membrane leakage 10 days after spray (DAS). The phenol content was significantly higher in the leaves of clodinafop-propargyl susceptible biotype than resistant biotype and herbicide application at various doses caused significant increase in the phenol content in a dose-dependent manner in both the biotypes. At 20 DAS, catalase activity exhibited significant decrease due to X and 2X doses of clodinafop in susceptible population but its activity was at par with control when clodinafop was applied at 0.25X and 0.5X doses. Application of clodinafop at X and 2X doses decreased the catalase activity at 1-7 DAS but no significant differences in activity were observed at 10-20 DAS in case of resistant population. Activities of superoxide dismutase and peroxidase exhibited an increase in susceptible P. minor population immediately after herbicide application but were decreased after 7 DAS indicating stress levels exceeded the plant defense limit and ultimately led to plant mortality. In resistant P. minor population, there was increase in SOD and POD activity up to 20 DAS indicating its oxidative stress tolerance.