Abstract
Background: The resistance of weeds to herbicides is a problem that has been increasingly studied because of its great importance in agriculture and rapid growth of this phenomenon worldwide. The quick detection of resistant plants is extremely important for resistance management. Weed resistance to herbicides can be detected through field, greenhouse and laboratory tests. A fast way of detecting resistance is using tissue culture method, where is possible to use resistant plant clones and obtain results faster than whole-plant method in greenhouse. Objective: The aims of the research were to detect the resistance of blackjack to herbicides inhibitors of the acetolactate synthase (ALS), addition in vitro cultivation; determine the herbicide concentration of imazethapyr to 95% control of the susceptible plant population; evaluate explants growth; and, determine the herbicide concentration added to the culture medium where is possible to distinguish a resistant from a susceptible plant. Methods: Experiments were carried out in greenhouse and tissue culture laboratory. Screening was performed to select resistant and susceptible biotypes, tests for specie establishment and dose response curves in vitro were made. Results: The herbicide concentration added to the culture medium that provided 95% susceptible biotype control and efficiently differentiated susceptible biotype from resistant one was 0.6μM of imazethapyr. Conclusions: This method helps recommendations of weed management and provides a quick decision to alternative control of this specie, thus avoiding major damage to the crops.
Highlights
Weeds, present in agricultural systems, interfere with the development of crops, causing great economic damage if not controlled at the right time.Weed control has been carried out primarily through the use of herbicides, due to lower cost and greater efficiency when compared to other control methods
The objectives of this study were: to detect blackjack biotypes resistant and susceptible to acetolactate synthase (ALS) in the Planalto region (RS); determine the best culture medium for the in vitro regeneration of blackjack; determine the concentration of the imazethapyr herbicide necessary for 95% control of the susceptible biotype population; evaluate the growth of resistant and susceptible explants subjected to different concentrations of imazethapyr herbicide; and determining the concentration of imazethapyr herbicide added to the medium in which it is possible to distinguish susceptible from resistant plants
Three experiments were carried out to obtain the herbicide concentration necessary for the blackjack resistance test in in vitro cultivation: the first consisted of collecting seeds and selecting the resistant and susceptible biotypes to be used in the test; the second consisted in the selection of the culture medium for the in vitro regeneration of blackjack; and the third consisted of dose-response curves tests of susceptible and resistant blackjack biotypes to imazethapyr herbicide in in vitro cultivation
Summary
Present in agricultural systems, interfere with the development of crops, causing great economic damage if not controlled at the right time.Weed control has been carried out primarily through the use of herbicides, due to lower cost and greater efficiency when compared to other control methods. There are about 500 biotypes with resistance to herbicides, of which 50 occur in Brazil (Heap, 2019) This plant, belonging to the Asteraceae family, has distribution worldwide, being one of the most competitive weeds in agricultural production systems (Santos and Cury, 2011). Among the weeds that have resistance problems, the blackjack (Bidens pilosa) stands out Conclusions: This method helps recommendations of weed management and provides a quick decision to alternative control of this specie, avoiding major damage to the crops
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