Publicação on-line; 37 ref.; 6 illus.; Summary (En)

ABSTRACT
Background: Soybean cultivation has been an option used to diversify
the production system and perform herbicide rotation in irrigated rice
crops in the lowland soils of the Rio Grande do Sul State, southern Brazil.
However, elevated salinity levels have been detected in these soils that
can inhibit plant growth due to the reduction of the osmotic potential of
the soil solution and can causes toxicity. The combination of stress factors
in the plantation areas can intensify deleterious effects, such as changes
in salinity associated with herbicides that trigger oxidative stress in crops.
Objective: This study aimed to evaluate osmotic potential, cell damage,
and enzyme activities of the antioxidant metabolism on soybean after
treatment with herbicides and salinity stress conditions.
Methods: For this purpose, completely randomized design was used in
a factorial scheme with three replicates. The A factor included four
herbicide treatments, as follows: control (no herbicide), sulfentrazone,
Smetolachlor, and sulfentrazone + S-metolachlor. The B factor was
represented by the following three salinity levels: 0 (control), 60, and
120 mM NaCl, which were applied 24 hours after soybean sowing.
Results: The results showed a significant alteration in the osmotic
potential of soybean plants, mainly at higher salt concentrations. Although
an increase in the lipid peroxidation has been detected in some
treatments, antioxidant enzyme action combined with osmotic adjustment
to reduce oxidative damage were mechanisms found to be employed by
plants to reduce hydrogen peroxide levels.
Conclusions: We concluded that herbicide treatment, in combination
with saline stress, can alter physiological and biochemical processes of
soybean plants

Keywords:
Glycine max
sulfentrazone
S-metolachlor
antioxidant enzymes
saline stress
cellular damage.