Detecção da resistência de Bidens pilosa, Echinochloa sp. e Oryza sativa a herbicidas inibidores da ALS pelo método de cultivo in vitro

Abstract

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 quick 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. The goals of the research were: to detect the resistance of blackjack, barnyardgrass and weedy rice to ALS inhibitors by herbicide addition in vitro cultivation; determine the herbicide concentration of imazethapyr and imazapyr+imazapic to 95% control of the susceptible plants 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. Experiments were carried out in greenhouse and tissue culture laboratory. Screening was performed to select resistant and susceptible biotypes of each species, tests for species establishment and dose response curves in vitro were made. The herbicide concentrations added to the culture medium that provided 95% susceptible biotypes control and efficiently differenciated susceptible biotypes from resistant ones were 0.6μM of imazethapyr for B. pilosa, 0.9 and 1.3μM of imazapyr+imazapic for Echinochloa sp. and O. sativa, respectively. The validation of this method helps recommendations of weed management and provides a quick decision to alternative control of these species, thus avoiding major damage to the crops.