Respostas de plantas de Eleusine indica sob diferentes condições hídricas a herbicidas inibidores da ACCase

Abstract

RESUMO-Objetivou-se neste estudo avaliar a eficiência de controle de herbicidas inibidores da ACCase aplicados em pós-emergência em plantas de Eleusine indica submetidas a diferentes teores de água no solo. Os experimentos foram conduzidos em casa de vegetação, com a aplicação de três diferentes herbicidas (fluazifop-p-butil, haloxyfop-methyl e sethoxydim + óleo mineral Assist); o delineamento experimental utilizado para cada herbicida foi inteiramente casualizado, com quatro repetições, constituído de um fatorial 3 x 4, sendo a combinação de três manejos hídricos (-0,03,-0,07 e-1,5 MPa) e quatro doses desses produtos (100, 50, 25 e 0% da dose recomendada). Os parâmetros fisiológicos avaliados foram: taxa fotossintética, condutância estomática, transpiração, temperatura da folha e matéria seca das plantas. As avaliações visuais de fitotoxicidade foram realizadas aos 14 dias após a aplicação. Os manejos hídricos aplicados não influenciaram o controle das plantas nos tratamentos testados, com exceção do herbicida sethoxydim, que teve sua eficiência hídrica prejudicada quando da deficiência hídrica nas aplicações das doses fracionadas. A taxa fotossintética, a transpiração e a condutância estomática foram maiores em plantas submetidas ao manejo hídrico de 13%, as quais apresentaram as menores temperaturas foliares em relação à temperatura ambiente. Palavras-chave: capim-pé-de-galinha, controle químico, restrição hídrica, planta daninha. ABSTRACT-The objective of this study to evaluate the control efficiency of ACCase-inhibiting herbicides applied during post-emergence on plants of Eleusine indica under different soil water contents. The experiments were conducted in a greenhouse, with the application of three different herbicides (fluazifop-p-butyl, haloxyfop-methyl and sethoxydim + oil Assist) Each herbicide experiment was arranged in a completely randomized design with four replications, consisting of a 3 x 4 factorial scheme, with the water management strategy combinations (-0.03,-0.07 and-1.5 MPa) and four doses of these products (100, 50, 25 and 0% of the recommended dose). The physiological parameters were: photosynthetic rate, stomatal conductance, transpiration, leaf temperature and plant dry weight. Visual assessments of plant toxicity were performed at 14 days after application. Water management did not influence plant control in the treatments tested, except for sethoxydim, which had its water efficiency affected as water deficiency occurred during the application of fractionated doses. Photosynthetic rate, transpiration, and stomatal conductance were higher in plants submitted to water management of 13%, also showing the lowest leaf temperatures in relation to ambient temperature.

Effect of water stress on herbicide efficiency applied to Urochloa decumbens

“…Plants without water stress transpire more due to increased stomatal opening, which is inversely proportional to leaf temperature; with increased perspiration, the leaf temperatures decrease. Coinciding with these results, Pereira et al (2011) described that the rate of photosynthesis, transpiration and stomatal conductance were higher in Eleusine indica plants kept without water stress (only with the potential of -0.03 MPa), which presented the lowest leaf temperatures compared to the environment and, consequently, presented higher dry matter and higher values of phytotoxicity with the application of the herbicide sethoxydim.…”

“…According to Deuba (1992), the amount of herbicide that penetrates the leaf cuticle of weeds is affected by conditions such as soil moisture, herbicide characteristics and developmental state of the weed. Corroborating these data, Pereira et al (2011) found that the control effectiveness of Eleusine indica using the herbicide sethoxydim was lower in plants grown under water deficit conditions.…”

“…There are few research studies in the international literature that address this topic; for example, the extant studies are based on other weed species (Pereira, 2010 and2011).…”

Geographic Distribution of Ryegrass Resistent to the Clethodim Herbicide in Rio Grande do Sul1

“…The ACCase present in poaceae is sensitive to inhibition by these herbicides (Rodrigues, 1994). However, some conditions are recommended so that the herbicides can reach a higher efficiency, such as the application when the plants present an elevated metabolic activity (Pereira et al, 2011).…”

Climate Change’s Impacts on Weeds and Herbicide Efficacy: A Review

“…Increases environmental stress on crops may make them more vulnerable to attack by insects and plant pathogens and less competitive with weeds (Patterson, 1995). Pereira et al, (2011) found that the efficacy of sethoxydim was lower in goosegrass (E. indica) plants grown under water-deficit conditions. Similarly, plantain signalgrass (Urochloa plantaginea) plants grown under water stress were not effectively controlled by ACCase-inhibiting herbicides when applied during the later growth stages (Pereira, 2010).…”