Rapid reduction of herbicide susceptibility in junglerice by recurrent selection with sublethal dose of herbicides and heat stress

Global climate change, specifically rising temperature, can alter the molecular physiology of weedy plants. These changes affect herbicide efficacy and weed management. This research aimed to investigate the combined effect of heat stress (HS) and sublethal doses of herbicides (four active ingredients) on adaptive gene expression and efficacy of herbicide on Echinochloa colona (L.) Link (junglerice). Three factors were evaluated; factor A was E. colona generation (G0-original population from susceptible standard; G1 and G2 were progenies of recurrent selection), factor B was herbicide treatment (florpyrauxifen-benzyl, glufosinate-ammonium, imazethapyr, quinclorac and nontreated check) and factor C was HS (30 and 45 ◦C). The herbicides were applied at 0.125× the recommended dose. Recurrent exposure to HS, combined with sublethal doses of herbicides, favors the selection of plants less susceptible to the herbicide. Upregulation of defense (antioxidant) genes (APX: Ascorbate peroxidase), herbicide detoxification genes (CYP450 family: Cytochrome P450), stress acclimation genes (HSP: Heat shock protein, TPP: Trehalose phosphate phosphatase and TPS: Trehalose phosphate synthase) and genes related to herbicide conjugation (UGT: UDP Glucosyltransferase) was significant. The positive regulation of these genes may promote increased tolerance of E. colona to these herbicides

Herbicide selectivity on soybean crop in soil humidity different function

Climate change is increasingly affecting the quality and quantity of the world's agricultural production. In the state of Rio Grande do Sul, the search for alternatives that maximize productivity and contribute to the economic sustainability of the wetland ecosystem emerges as a justification for the use of the soybean crop in these areas, since it is one of the main commodities of Brazilian agribusiness. Chemical weed control constitutes the most widely adopted management method, however, little is known as the soybean crop responds to the use of herbicides in different soil moisture. Thus, this study aimed to evaluate physiological and biochemical responses in soy after applying herbicides recommended plants for growing in three soil moisture levels. The experiment was arranged in a randomized design in a factorial arrangement (7x3) with four replications. It was used to cultivate soy BMX Power RR, grown in pots (8L), keeping three plants per pot which, in stage V3 were subjected to three soil moisture: field capacity, Dry soil (50% below capacity field) and saturated soil (50% above the field capacity), followed by herbicide treatment: Glyphosate, Sulfentrazone, S-metolachlor, Glyphosate + Sulfentrazone, Glyphosate + S-metolachlor, Glyphosate + Sulfentrazone + S-metolachlor, beyond without herbicide treatment. At seven, 14 and 28 days after application (DAA) were evaluated chlorophyll content, flavonoids, nitrogen balance and gas exchange in the third trefoil fully developed. This time collected is still, leaf material for evaluation of osmotic potential, proline content, hydrogen peroxide, lipid peroxidation and activity of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). For pigments and nitrogen balance index was little variation between treatments, since gas exchange were more affected in dry soil plants, especially at 14 and 28 DAA, with marked effect by the presence of herbicides. At seven DAA the herbicide Glyphosate in dry soil resulted in greater activation of antioxidant enzymes SOD and CAT, as well as increased production of hydrogen peroxide and is probably linked to increased oxidative stress caused by this herbicide. However, after 28 days from the application, increased synthesis of proline in this treatment, which leads to osmotic adjustments and consequent lower enzymatic activity. In saturated soil and field capacity responses triggered by Glyphosate herbicides, Sulfentrazone, S-metolachlor does not follow a pattern, but, in general, lead to lower stress compared to dry soil. The results of this study show that although the variation in soil moisture, changes the soybean crop metabolism, the application of herbicides in dry soil conditions or saturated accentuates this effect and may result in damage to the crop.Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPqAs mudanças climáticas estão cada vez mais afetando a qualidade e a quantidade da produção agrícola mundial. No estado do Rio Grande do Sul, a busca por alternativas que maximizem a produtividade e contribuam para a sustentabilidade econômica do ecossistema várzea surge como uma justificativa para a utilização da cultura da soja nestas áreas, visto que é uma das principais commodities do agronegócio brasileiro. O controle químico de plantas daninhas se constitui no método de manejo mais adotado, porém, pouco se sabe como a cultura da soja responde ao uso de herbicidas em diferentes umidades do solo. Desta forma, o presente estudo teve por objetivo avaliar respostas fisiológicas e bioquímicas em plantas de soja após a aplicação de herbicidas recomendados para a cultura em três níveis de umidade do solo. O experimento foi arranjado em delineamento inteiramente casualizado em esquema fatorial (7x3) com quatro repetições. Foi utilizada a cultivar de soja BMX Potência RR, cultivadas em vasos (8L), mantendo-se três plantas por vaso as quais, no estádio V3 foram submetidas a três umidades do solo: Capacidade de campo, Solo seco (50% abaixo da capacidade de campo) e Solo saturado (50% acima da capacidade de campo), seguido da aplicação dos tratamentos herbicidas: Glyphosate, Sulfentrazone, S-metolachlor, Glyphosate+Sulfentrazone, Glyphosate+S-metolachlor, Glyphosate+Sulfentrazone+S-metolachlor, além do tratamento sem herbicida. Aos sete, 14 e 28 dias após a aplicação (DAA) foram avaliados o índice de clorofilas, flavonoides, balanço de nitrogênio e as trocas gasosas no terceiro trifólio completamente desenvolvido. Neste período coletou-se ainda, material foliar para avaliação de potencial osmótico, teor de prolina, peróxido de hidrogênio, peroxidação de lipídios e atividade das enzimas antioxidantes superóxido dismutase (SOD), catalase (CAT) e ascorbato peroxidase (APX). Para os pigmentos e índice de balanço de nitrogênio houve pequena variação entre os tratamentos, já as trocas gasosas foram mais afetadas nas plantas em solo seco, principalmente aos 14 e 28 DAA, com efeito acentuado pela presença dos herbicidas. Aos sete DAA o herbicida Glyphosate em solo seco resultou em maior ativação das enzimas antioxidantes SOD e CAT, além da maior produção de peróxido de hidrogênio estando, provavelmente, vinculado ao aumento do estresse oxidativo causado por este herbicida. Entretanto, após 28 dias da aplicação, aumenta a síntese de prolina neste tratamento, o que leva ao ajuste osmótico, e consequente menor atividade enzimática. Em solo saturado e capacidade de campo as respostas desencadeadas pelos herbicidas Glyphosate, Sulfentrazone, S-metolachlor não seguem um padrão, porém, de maneira geral, levam a um menor estresse comparado ao solo seco. Os resultados deste estudo mostram que, embora a variação na umidade do solo, altera o metabolismo da cultura da soja, a aplicação de herbicidas em condições de solo seco ou saturado acentua este efeito, podendo resultar em prejuízos para a cultura

Rapid reduction of herbicide susceptibility on Echinochloa colona by recurrent selection with sublethal dose of herbicides and abiotic stress

Não possuiConselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPqNão possu

Rapid Reduction of Herbicide Susceptibility in Junglerice by Recurrent Selection with Sublethal Dose of Herbicides and Heat Stress

Global climate change, specifically rising temperature, can alter the molecular physiology of weedy plants. These changes affect herbicide efficacy and weed management. This research aimed to investigate the combined effect of heat stress (HS) and sublethal doses of herbicides (four active ingredients) on adaptive gene expression and efficacy of herbicide on Echinochloa colona (L.) Link (junglerice). Three factors were evaluated; factor A was E. colona generation (G0-original population from susceptible standard; G1 and G2 were progenies of recurrent selection), factor B was herbicide treatment (florpyrauxifen-benzyl, glufosinate-ammonium, imazethapyr, quinclorac and nontreated check) and factor C was HS (30 and 45 °C). The herbicides were applied at 0.125× the recommended dose. Recurrent exposure to HS, combined with sublethal doses of herbicides, favors the selection of plants less susceptible to the herbicide. Upregulation of defense (antioxidant) genes (APX: Ascorbate peroxidase), herbicide detoxification genes (CYP450 family: Cytochrome P450), stress acclimation genes (HSP: Heat shock protein, TPP: Trehalose phosphate phosphatase and TPS: Trehalose phosphate synthase) and genes related to herbicide conjugation (UGT: UDP Glucosyltransferase) was significant. The positive regulation of these genes may promote increased tolerance of E. colona to these herbicides

Recurrent Selection with Low Herbicide Rates and Salt Stress Decrease Sensitivity of Echinochloa colona to Imidazolinone

Weeds represent an increasing challenge for crop systems since they have evolved adaptability to adverse environmental conditions, such as salinity stress. Herbicide effectiveness can be altered by the quality of water in which the weed is growing. This research aimed to study the combined effect of salt stress and recurrent selection with a sublethal dose of imidazolinone herbicides in the shifting of the sensitivity of Echinochloa colona (L.) Link (junglerice) to imidazolinone herbicides. This study was divided into two experiments; in experiment I, three recurrent selection cycles were conducted in Pelotas/RS/Brazil with imazapic + imazapyr at 0.125× the field rate; and in experiment II, three recurrent selection cycles were conducted in Fayetteville/AR/USA with imazethapyr, at 0.125× the recommended dose. Salt stress was implemented by irrigation with 120 mM sodium chloride (NaCl) solution. The effective dose for 50% control of the population (ED50) values increased from the field population to the second generation (G2) after recurrent selection with a sublethal dose of imidazolinone combined with salt stress, supporting the hypothesis of reduced susceptibility by the combination of these abiotic factors. Recurrent exposure to a sublethal dose of imazapic + imazapyr or imazethapyr, combined with salt stress, reduced susceptibility of Echinochloa colona (L.) plants to imidazolinone herbicides