Ação de mefenpyr como "safener" e estimulante de crescimento de milho
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Data
2021-12-10
Autores
Bianchi, Leandro [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Safeners são substâncias que atuam como protetores de injúrias causadas por herbicidas, como exemplo o mefenpyr-diethyl, cuja ação protetora se dá principalmente em cereais de inverno ao uso de herbicidas inibidores da Acetil Coenzima A carboxilase (ACCase) e Acetolactato sintetase (ALS). Seu mecanismo de ação está atrelado a enzimas que metabolizam herbicidas, ativado por processos fisiológicos e bioquímicos. Contudo, ainda não está claro todas as respostas da utilização de safeners em plantas. Assim, neste trabalho foi realizado um compilado de informações sobre safeners, trazendo uma revisão de literatura abordando os avanços e descobertas sobre a temática (Capítulo 1) e investigado os efeitos protetores da aplicação de mefenpyr-diethyl aos danos por herbicidas na cultura do milho, explorando seus efeitos secundários (Capítulos 2 e 3). Uma série de experimentos foram desenvolvidos para avaliar esses efeitos, realizados no Núcleo de Pesquisa avançada em Matologia (NUPAM). O primeiro experimento (capítulo 2) objetivou avaliar a ação protetora do mefenpyr-diethyl à aplicação de herbicidas inibidores da ACCase, em casa-de-vegetação, combinando o mefenpyr-diethyl (50 g ia ha-1) com herbicidas, sendo: controle, mefenpyr-diethyl, mefenpyr-diethyl + fenoxaprop-p-ethyl (110 g ia ha-1), mefenpyr-diethyl + haloxyfop-p-methyl (62,35 g ia ha-1), mefenpyr-diethyl + clethodim (108 g ia ha-1), mefenpyr-diethyl 5 dias antes da aplicação de fenoxaprop-p-ethyl (110 g ia ha-1), mefenpyr-diethyl 5 dias antes da aplicação de haloxyfop-p-methyl (62,35 g ia ha-1), e mefenpyr-diethyl 5 dias antes da aplicação de clethodim. Realizaram-se avaliações de fitotoxicidade, altura, massa seca, conteúdo total de lipídeos e acúmulo de parte aérea e de massa. Verificou-se que a aplicação de mefenpyr-diethyl não proporcionou proteção suficiente aos herbicidas inibidores de ACCase, entretanto o uso de mefenpyr-diethyl de maneira isolada levou a aspectos estimulantes para a planta de milho, com incremento de massa seca. Para investigar melhor este efeito secundário, foi realizado um segundo conjunto de estudos (Capítulo 3) através da curva dose-resposta, objetivando estabelecer a melhor dose estimulante e o estádio de aplicação, e posteriormente aplicando esses resultados as condições de campo. A primeira parte do experimento foi desenvolvido em casa-de-vegetação com 5 doses do produto: 0; 12,5; 25; 50 e 100 g ia ha-1. O mefenpyr-diethyl foi aplicado em dois estádios fenológicos e o experimento repetido em duas épocas. Foram realizadas avaliações de crescimento diário de altura, área foliar e o acúmulo de massa seca ao longo de 21 dias após a aplicação. A partir da seleção da melhor dose estimulante, foram validados os resultados à campo em relação ao desempenho da cultura, aos componentes produtivos e sistema fotossintético. Neste caso, o experimento continha a testemunha e 3 estádios de aplicação (tratamento de semente (TS), V4 e V6), com 4 repetições e realizados em duas safras. A melhor dose encontrada foi de 50 g ia ha-1 quando aplicado no estádio V3 e V4, proporcionando além de maior altura e área foliar, um acumulo de 2 e 1,3 vezes maior de massa seca em relação à testemunha, respectivamente. À campo, os estímulos foram evidentes na aplicação foliar em v4 e em TS, proporcionando respostas estimulantes na altura, área foliar e na massa seca. Além disso, houve resultados positivos para componentes produtivos com o uso de mefenpyr-diethyl.
Safeners are substances that act as protectors against injuries caused by herbicides, such as mefenpyr-diethyl, whose protective action occurs mainly in winter cereals when using herbicides that inhibit Acetyl Coenzyme A Carboxylase (ACCase) and Acetolactate synthetase (ALS). Its mechanism of action is linked to enzymes that metabolize herbicides, activated by physiological and biochemical processes. However, it is still not clear all the answers of the use of safeners in plants. Thus, in this work, a compilation of information about safeners was carried out, bringing a literature review addressing the advances and discoveries about the topic (Chapter 1) and investigating the protective effects of the mefenpyr-diethyl application to the damages by herbicides in maize, exploring its secondary effects (Chapters 2 and 3). A series of experiments were developed to evaluate these effects, carried out at the Nucleus for Advanced Research in Matology (NUPAM). The first experiment (Chapter 2) aimed to evaluate the protective action of mefenpyr-diethyl to the application of ACCase inhibitor herbicides, in a greenhouse, combining mefenpyr-diethyl (50 g ai ha-1) with herbicides, as follows: control, mefenpyr-diethyl, mefenpyr-diethyl + fenoxaprop-p-ethyl (110 g ai ha-1), mefenpyr-diethyl + haloxyfop-p-methyl (62.35 g ai ha-1), mefenpyr-diethyl + clethodim (108 g ai ha-1), mefenpyr-diethyl 5 days before application of fenoxaprop-p-ethyl (110 g ai ha-1), mefenpyr-diethyl 5 days before application of haloxyfop-p-methyl (62.35 g ai ha-1), and mefenpyr-diethyl 5 days before clethodim application. Phytotoxicity, height, dry mass, total lipid content and shoot and mass accumulation were carried out. It was found that the application of mefenpyr-diethyl did not provide sufficient protection to ACCase inhibitor herbicides, however the use of mefenpyr-diethyl alone led to stimulating aspects for the maize plant, with an increase in dry mass. To better investigate this secondary effect, a second set of studies was carried out (Chapter 3) through the dose-response curve, aiming to establish the best stimulant dose and the stage of application, and later applying these results to field conditions. The first part of the experiment was carried out in a greenhouse with 5 doses of the product: 0; 12.5; 25; 50 and 100 g ai ha-1. Mefenpyr-diethyl was applied at two phenological stages and the experiment was repeated at two times. Daily growth assessments of height, leaf area and dry mass accumulation were carried out over 21 days after application. From the selection of the best stimulant dose, the results were validated in the field in relation to crop performance, productive components and photosynthetic system. In this case, the experiment contained the control and 3 application stages (seed treatment (TS), V4 and V6), with 4 replications and carried out in two seasons. The best dose found was 50 g ai ha-1 when applied at the V3 and V4 stages, providing, in addition to greater height and leaf area, an accumulation of 2 and 1.3 times greater dry mass in relation to the control, respectively. In the field, the stimuli were evident in the foliar application in v4 and in TS, providing stimulating responses in height, leaf area, and in the dry mass. In addition, there were positive results for productive components with the use of mefenpyr-diethyl.
Safeners are substances that act as protectors against injuries caused by herbicides, such as mefenpyr-diethyl, whose protective action occurs mainly in winter cereals when using herbicides that inhibit Acetyl Coenzyme A Carboxylase (ACCase) and Acetolactate synthetase (ALS). Its mechanism of action is linked to enzymes that metabolize herbicides, activated by physiological and biochemical processes. However, it is still not clear all the answers of the use of safeners in plants. Thus, in this work, a compilation of information about safeners was carried out, bringing a literature review addressing the advances and discoveries about the topic (Chapter 1) and investigating the protective effects of the mefenpyr-diethyl application to the damages by herbicides in maize, exploring its secondary effects (Chapters 2 and 3). A series of experiments were developed to evaluate these effects, carried out at the Nucleus for Advanced Research in Matology (NUPAM). The first experiment (Chapter 2) aimed to evaluate the protective action of mefenpyr-diethyl to the application of ACCase inhibitor herbicides, in a greenhouse, combining mefenpyr-diethyl (50 g ai ha-1) with herbicides, as follows: control, mefenpyr-diethyl, mefenpyr-diethyl + fenoxaprop-p-ethyl (110 g ai ha-1), mefenpyr-diethyl + haloxyfop-p-methyl (62.35 g ai ha-1), mefenpyr-diethyl + clethodim (108 g ai ha-1), mefenpyr-diethyl 5 days before application of fenoxaprop-p-ethyl (110 g ai ha-1), mefenpyr-diethyl 5 days before application of haloxyfop-p-methyl (62.35 g ai ha-1), and mefenpyr-diethyl 5 days before clethodim application. Phytotoxicity, height, dry mass, total lipid content and shoot and mass accumulation were carried out. It was found that the application of mefenpyr-diethyl did not provide sufficient protection to ACCase inhibitor herbicides, however the use of mefenpyr-diethyl alone led to stimulating aspects for the maize plant, with an increase in dry mass. To better investigate this secondary effect, a second set of studies was carried out (Chapter 3) through the dose-response curve, aiming to establish the best stimulant dose and the stage of application, and later applying these results to field conditions. The first part of the experiment was carried out in a greenhouse with 5 doses of the product: 0; 12.5; 25; 50 and 100 g ai ha-1. Mefenpyr-diethyl was applied at two phenological stages and the experiment was repeated at two times. Daily growth assessments of height, leaf area and dry mass accumulation were carried out over 21 days after application. From the selection of the best stimulant dose, the results were validated in the field in relation to crop performance, productive components and photosynthetic system. In this case, the experiment contained the control and 3 application stages (seed treatment (TS), V4 and V6), with 4 replications and carried out in two seasons. The best dose found was 50 g ai ha-1 when applied at the V3 and V4 stages, providing, in addition to greater height and leaf area, an accumulation of 2 and 1.3 times greater dry mass in relation to the control, respectively. In the field, the stimuli were evident in the foliar application in v4 and in TS, providing stimulating responses in height, leaf area, and in the dry mass. In addition, there were positive results for productive components with the use of mefenpyr-diethyl.
Descrição
Palavras-chave
efeito secundário, estímulo, Zea mays, seletividade, secondary effect, stimulation, selectivity