Role of seed environment and covering structures on large crabgrass germination

The success of large crabgrass (Digitaria sanguinalis) growing among summer crops in Argentina, may be partly explained by its escape from weed controls related to the emergence of different seedlings cohorts determined by seed dormancy and germination requirements. The objectives of this work were to evaluate the effect of temperature, red (R):far-red (FR) ratio and the possible role of the caryopses covering structures on the release of seed dormancy in D. sanguinalis. Therefore, the effects of moist pre-treatment duration, light and temperature, as well as the caryopsis covering structures, and imbibition with H2O2 and the extract of caryopses covers on seed germination, were investigated. Moist pre-treatment at 5 and 20 °C promoted dormancy release and fluctuating temperatures between 20/30 °C and light promoted germination. However, exposure to 30 min of light with a high R:FR ratio reduced germination. Removing or puncturing some of the caryopsis covering structures, as well as imbibition with 2.6 M H2O2 enhanced seed germination. Results suggest that the extended seedling emergence throughout the season could be due to the influence of the environmental factors studied here on dormancy release and germination, and that seed covering structures have an important role in seed dormancy imposition for this species.