The objective of this study was to evaluate the response of hairy beggarticks plants to different doses of glufosinate ammonium and the range in sensitivities of the plants and their progenies to the herbicide. Three studies were conducted, all in a greenhouse and repeated at different times. In the first study, two experiments were conducted to examine the dose–response curve, and the treatments were seven different doses of the herbicide glufosinate ammonium (0, 50, 100, 200, 400, 800, and 1,600 g ai ha−1), with four replications each. In the second study, which examined the range in sensitivity of hairy beggarticks to glufosinate ammonium, 44 plants were sprayed with a dose of 200 g ai ha−1of the herbicide. Finally, in the third study, the range in sensitivity of the progeny of hairy beggarticks to glufosinate ammonium was investigated; in this experiment, the progenies of seven of the previous plants were sprayed with 200 g ai ha−1of herbicide. The ammonium contents in the tissues were measured and percent injury wase visually assessed. Ammoniun content in hairy beggarticks leaves was increased more than seven times by glufosinate application and the maximum ammonium content was observed for the highest dose of the herbicide. Variability existed in the ammonium content among the individuals of the population of hairy beggarticks; however, the behavior was not replicated in the same way in the progenies. The survival of the plants after application of the herbicide allows the production of progenies with wide variability in their sensitivity to the product, independent of the behavior for the progenitor plants.

-This study aimed to identify the response of wandering jew (Commelina benghalensis L.) plants to different doses of glufosinate ammonium and the sensitivity of plants populations to the herbicide. Two studies were conducted, both in a greenhouse, and were repeated at different times. In the first study, two experiments were conducted to examine the dose-response curve using seven different doses of the glufosinate ammonium herbicide (0, 50, 100, 200, 400, 800, and 1600 g a.i. ha -1 ) with four replicates each. In the second study, which examined the range in sensitivity of wandering jew plants to glufosinate ammonium, 26 plants were sprayed with a dose of 200 g a.i. ha -1 herbicide. Visual assessments of percent injury and measurements of leaf tissue ammonium content were conducted. The use of untreated wandering jew control plants allowed for the correlation of glufosinate ammonium treatment with the ammonium concentrations in treated plant tissues; the ammonium concentration increased as a function of herbicide application, albeit not linearly with the dose. Ammonium content varied among individuals of the wandering jew plant population.Keywords: Ammonia. Commelina benghalensis L.. Glutamine synthetase. Weed. VARIAÇÃO DA SENSIBILIDADE DE PLANTAS DE TRAPOERABA AO AMÔNIO GLUFOSINATERESUMO -Esse trabalho teve como objetivo identificar a resposta de plantas de trapoeraba (Commelina benghalensis L.) a diferentes doses de amônio glufosinate e a sensibilidade de uma população de plantas ao herbicida. Foram realizados dois estudos, ambos implantados em casa de vegetação e repetidos em diferentes momentos. No primeiro, referente à curva de dose-resposta, realizou-se dois experimentos, tendo como tratamentos sete doses do herbicida amônio glufosinate (0; 50; 100; 200; 400; 800; 1600 g i.a. ha -1 ), com quatro repetições cada. Já no segundo, referente à variação da sensibilidade da trapoeraba ao amônio glufosinate, 26 plantas foram pulverizadas com a dose de 200 g i.a. ha -1 do herbicida. Realizou-se avaliações visuais de injúria e análises do teor de amônia nos tecidos foliares. O controle de plantas de trapoeraba pelo amônio glufosinate pode ser correlacionado ao teor de amônia nos tecidos vegetais, que aumenta em função da aplicação do herbicida, porém não de forma linear em função da dose. Houve variabilidade quanto ao teor de amônia entre indivíduos de uma população de trapoeraba.Palavras-chave: Amônia. Commelina benghalensis L.. Glutamina sintetase. Planta daninha.

-This study aimed to assess the response of Urochloa decumbens plants to different doses of glufosinate ammonium, and the sensitivity of plant population to the herbicide. Two studies were conducted, both in greenhouse and repeated at different times. In the dose-response analysis, two experiments were conducted using seven doses of the glufosinate ammonium (0, 50, 100, 200, 400, 800, and 1,600 g a.i. ha

The sensitivity of weed species to herbicides is variable, and the behavior can be repeated or not in the next generation. The objective of this study was to evaluate the response of morningglory plants to different doses of glufosinate ammonium and the sensitivity of plant populations and their progenies to the herbicide. Three studies were conducted, all in a greenhouse and repeated in two periods. In the first study, two experiments were conducted to examine the dose-response curve, and the treatments were seven different doses of the herbicide glufosinate ammonium (0, 50, 100, 200, 400, 800, and 1,600 g a.i. ha-1), with four replications each. In the second study, which examined the range in sensitivity of morningglory to glufosinate ammonium, 44 plants were sprayed with a dose of 200 g a.i. ha-1 of the herbicide. Finally, in the third study, the range in sensitivity of morningglory progenies to glufosinate ammonium was investigated; in this experiment, the progenies of seven of the previous plants were sprayed with 200 g a.i. ha-1 of herbicide. The ammonium contents in the tissues were measured, and percent injury were visually assessed. Ammonium content in morningglory leaves was increased more than seven times by glufosinate application and the maximum ammonium content was observed for the highest herbicide dose. Variability existed in the ammonium content among the individuals of the morningglory population; however, the behavior was not replicated in the same way in progenies. Plants survival after herbicide application allows the production of progenies with wide variability in their sensitivity to the product, regardless of the behavior verified in progenitor plants.

We aimed to study the response of Conyza sumatrensis to different doses of glufosinate, intrapopulation variation in sensitivity to the herbicide, and the heritability of phenotypic response, and model the evolution of resistance. Three studies were conducted in the greenhouse with two repetitions. First, we tested doses of glufosinate (0, 50, 100, 200, 400, 800 g a.i. ha −1) plus a nontreated check, with four replications. Second, we examined the range in sensitivity of 44 plants to 200 g a.i. ha −1 glufosinate. Third, we evaluated the sensitivity of the progeny of six glufosinate-treated plants to 200 g a.i. ha −1 glufosinate. Plant response was evaluated visually and the ammonium content in leaf tissues was measured. Glufosinate at 400 g a.i. ha −1 caused the highest injury to C.sumatrensis plants. Ammonia accumulation occurred in response to glufosinate treatment, regardless of dose. Ammonia accumulation was correlated strongly with the level of visible plant injury; thus, it is a good indicator of herbicide efficacy. Sensitivity to glufosinate was highly variable within the population. Plants with high ammonia concentration (high injury) after treatment with glufosinate produced progenies that also had high ammonia concentrations after herbicide treatment. The variation in ammonia accumulation among siblings was high. Simulating the exclusion of plants that accumulated more ammonia produced a population that is expected to be less sensitive to glufosinate in the next generation. The stronger the selection pressures by a simulated treatment with glufosinate, the greater the reduction in ammonia accumulation in the progeny and expected sensitivity to glufosinate.