Emergence of weed seeds affected by depth and time in the soil

Abstract

Weeds are undesirable in certain areas, especially agricultural. The germination and seedling emergence of its seeds is mainly controlled by climatic factors, depth and time of exposure in the soil, in addition to factors related to the species. The objective was to evaluate the seedling emergence of species of black pickerel (Bidens pilosa L.), horseweed (Conyza bonariensis (L.) Cronquist), pigweed (Amaranthus hybridus var. paniculatus (L.) Uline & W.L. Bray), and bitter grass (Digitaria insularis (L.) Fedbe) at different times and soil depths. Seed seedling emergence was evaluated weekly in soil incubated in a completely randomized design, four replications, temperature of 28º, photoperiod of 12 hours and time of 56 days. Seedling emergence was evaluated in four seed arrangements in the soil: 0 - surface, 0-5, 5-10, 10-15 cm. The higher seedling emergence and uniform distribution over time occurred with the black pickerel specie and seeds arranged on the soil surface (17 plants). Horseweed did not seedling emergence. Pigweed did not show high emergency (11 plants) and bitter grass had greater germination on the soil surface (7 seedlings). Thus, black pickerel and bitter grass seeds arranged on the surface have greater seedling emergence compared to those deeper. Furthermore, the seedling emergence of bitter grass and pigweed suffers a reduction over time. This study better understood the germination and seedling emergence of important weeds, which is fundamental for the assertiveness of management programs in agricultural systems.