Abstract
ABSTRACT: The objectives of this research were to evaluate the interaction between herbicides mixed with saflufenacil for the control of barnyardgrass and to determine the effect on photosynthetic and chlorophyll fluorescence parameters. The experiment was conducted in a greenhouse in a 2x8 factorial scheme, whose factor A tested resistant and susceptible biotypes; and factor B the herbicides: saflufenacil (70 g a.i. ha-1), clomazone (180 g a.i. ha-1), imazapyr + imazapic (73.5 + 24.5 g a.i. ha-1), and cyhalofop (360 g a.i. ha-1), the mixtures of these herbicides with saflufenacil, and control without treatment. Weed control was assessed 7, 14, 21 and 28 days after herbicide application (DAA), as well as shoot dry matter at 28 DAA, photosynthetic parameters using infrared gas analyzer (IRGA), and emission of chlorophyll a fluorescence after 24 and 28 hours of application of treatments, respectively, and interaction of herbicides. Combination of saflufenacil with the herbicides tested in general did not change the response of both barnyardgrass biotypes to the herbicides used. The resistant biotype showed a lower negative effect on chlorophyll fluorescence and photosynthesis parameters in the combination of herbicides with saflufenacil. The herbicide cyhalofop was effective for the control of ALS-susceptible and resistant barnyardgrass.
Highlights
Brazil has succeeded in raising agricultural productivity of flooded rice (Oryza sativa) due to new technologies, such as the Clearfield® (CL) system, which facilitated the control of major weeds such as weedy rice (Oryza sativa) and barnyardgrass (Echinochloa spp.) (CONAB, 2019)
Factor A tested the resistant and susceptible to ALS-inhibiting herbicides barnyardgrass biotypes; factor B consisted of different herbicides treatments, namely saflufenacil (70 g a.i. ha-1), clomazone (180 g a.i. ha-1), imazapyr+imazapic (73.5+24.5 g a.i. ha-1), cyhalofop-butyl (360 g a.i. ha-1), a combination of these herbicides with saflufenacil, and the control
Barnyardgrass control with application of cyhalofop alone and mixed with saflufenacil showed a satisfactory result for both biotypes from 14 days after herbicide application (DAA) and, in general, higher than 90% at 28 DAA, different from the other treatments
Summary
Brazil has succeeded in raising agricultural productivity of flooded rice (Oryza sativa) due to new technologies, such as the Clearfield® (CL) system, which facilitated the control of major weeds such as weedy rice (Oryza sativa) and barnyardgrass (Echinochloa spp.) (CONAB, 2019). The CL system has rice genotypes that are tolerant to the imidazolinones (IMI) chemical group, and has become the major form of weed control in rice Brazilian fields. Competition for light and CO2 is of great importance because this interferes with the rate of photosynthesis and the physiological activity of roots, with direct effect on biomass accumulation and crop yield (ZHANG et al, 2017). Another factor that enhanced competition is the physiological and morphological similarity of plants of the same family, as sunlight since solar irradiation and other demands for resources are often similar (GALON et al, 2018). Yield losses are related to presence of resistant barnyardgrass biotypes on rice fields and to avoid it, the farmers are using tank-mix to their control
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
