Publicação on-line; 30 ref.; 11 illus.; Summary (En)

ABSTRACT
Background: Substantial losses to crops can occur due to the presence
of sourgrass in agroecosystems, which is promoted by its seed dispersal
ability. Environmental factors can affect sourgrass germination and
emergence.
Objective: The objective of this study was to determine the effects of
water restriction, salinity, and depth of sowing on the sourgrass
germination and emergence processes.
Methods: Experiments using sourgrass seeds were conducted under
controlled conditions simulating osmotic and saline stress and seeding
depths. The data collected was submitted to analysis of variance and
adjusted to models by regression analysis.
Results: Smaller osmotic potentials reduced germination, normal
seedlings, and increased quiescence, with no germination occurring from
-0.80 MPa. Salinity caused a decrease in germination from 20 mM NaCl,
influencing the percentage of normal and abnormal seedlings and
quiescent seeds. Seed depth influenced the emergence of seedlings, with
the maximum percentage of emergence (83%) in the seeds placed on the
substrate surface. The maximum depth from which sourgrass seedlings
emerged was 7.6 cm.
Conclusions: The results lead to the conclusion that the sourgrass
germination process tolerates low osmotic potentials and salinity levels.
Despite being small sized seeds, they can emerge from high depths.
These characteristics justify its occurrence in several regions and
agroecosystems, especially in perennial and no-till crops lacking soil
cover.

Keywords:
Digitaria insularis
water stress
seeding depth.