Publicação on-line; 25 ref.; 1 table; 2 illus.; Summary (En)

ABSTRACT
Background: Rice lines displaying resistance to quizalofop-p-ethyl
(quizalofop), an acetyl coenzyme A carboxylase (ACCase)-inhibiting
herbicide, were developed to facilitate control of imidazolinone-resistant
weedy rice (red rice), as well as other susceptible grasses.
Objective: To assess the sensitivity of weedy rice accessions from Brazil
to quizalofop.
Methods: Two bioassays were conducted on the greenhouse from March
to June 2016, in a completely random design with a two-factor factorial
combination of treatments and four replications. The factor A was weedy
rice accession and factor B was quizalofop rates (0, 25 and 50 g a.i. ha-1).
It was assessed a total of 84 genotypes in the two bioassays, composed
of 78 weedy rice accessions, 4 rice cultivars, and 2 lines resistant to
aryloxyphenoxypropionate (AOPP) herbicides. Quizalofop was applied
the 2-leaf stage. Weedy rice control was evaluated at 28 and 22 days
after treatment (DAT), respectively for bioassay I and II, using a scale of
0% (no control) to 100% (dead).
Results: All weedy rice accessions were susceptible to quizalofop, being
controlled 100% with 50 g a.i. ha-1. Rice lines SC 964 and SC 965,
resistant to AOPP herbicides, were not injured by quizalofop.
Conclusions: quizalofop is an effective tool for weedy rice control in
ACCase-resistant rice.

Keywords:
aryloxyphenoxypropionate
ACCase inhibitor
red rice
Oryza sativa.