Impact of post-emergent imazethapyr on morpho-physiological and biochemical responses in lentil (Lens culinaris Medik.)

Yield reduction in lentil crop due to weed infestation is a key hindrance to its growth due to poor weed-crop competition. Imazethapyr (IM), a selective herbicide, target acetolactate synthase (ALS) which catalyzes the first reaction in biosynthesis of branched chain amino acids, required for plant growth and development. The objective of the present study was to investigate the impact of IM treatment on weeds, ALS enzyme activity, antioxidant capacity, osmolyte accumulation, growth and yield related parameters in lentil genotypes. Two IM tolerant (LL1397 and LL1612) and two susceptible (FLIP2004-7L and PL07) lentil genotypes were cultivated under weed free, weedy check and IM treatments. Weed control efficiency reached its peak at 21 days after spray (DAS). Imazethapyr treatment decreased chlorophyll and carotenoid content up to 28 DAS with higher reduction in susceptible genotypes. FLIP2004-7L and PL07 had reduced plant height and lower number of pods under IM treatment which resulted in decreased seed yield. Higher ALS activity in LL1397 and LL1612 at 21 DAS, higher antioxidant capacity and glycine betaine content both at 21 and 28 DAS and lower decrease in relative leaf water content might be mediating herbicide tolerance in these genotypes that led to higher seed yield. The identified IM tolerance mechanism can be used to impart herbicide resistance in lentil.

Automated summary

Yield reduction in lentil crop due to weed infestation is a major obstacle to its growth. This study investigated the impact of the selective herbicide imazethapyr (IM) on lentil genotypes. IM treatment led to a decrease in chlorophyll and carotenoid content, particularly in susceptible genotypes. Susceptible genotypes also showed reduced plant height, lower number of pods, and decreased seed yield under IM treatment. In contrast, tolerant genotypes had higher acetolactate synthase (ALS) activity, antioxidant capacity, and glycine betaine content, as well as less decrease in relative leaf water content, resulting in higher seed yield. These findings suggest that the identified IM tolerance mechanism can be used to enhance herbicide resistance in lentil.