Activity of acetolactate synthase (ALS) of redroot pigweed in relation to imazethapyr application
Seed of weed species redroot pigweed for which there exist possibility of resistance occurrence were collected from different localities in Autonomous Province of Vojvodina, the northern part of the Republic of Serbia (Krivaja, Kikinda, Vrbas and Kačarevo). Studies on herbicide resistance were performed in the period of 2003 to 2009. Biological studies included whole plant studies on plants grown in net-house and biochemical researches confirmed the activity of acetolactate synthase enzyme in vivo. In order to study the occurrence of resistance during the tests, herbicide products based upon active ingredient imazethapyr were used. Values of resistance index were calculated in relation to the referent population collected from the ruderal sites. Based upon the results of biological studies in the redroot pigweed plants from the locality of Krivaja, the presence of resistance was established. Immunological tests confirmed the results of biological assays given that the activity of ALS enzyme was found in all the studied populations. Established resistance is a consequence of physiological changes and accelerated metabolism.
Key words: Redroot pigweed, imazetaphyr, acetolactate synthase activity, dose response curve, resistance.