EMERGENCE OF WEED SPECIES ( Brachiaria ) UNDER SUGARCANE STRAW

Abstract

-The objective of this study was to evaluate the effects of soil cover with sugarcane residue on weed emergence of four weeds from the genus Brachiaria. The study was conducted in an area whose soil was classified as Red Nitosol. Seven different amounts of sugarcane residue (0, 3, 6, 9, 12, 15 and 18 ton ha -1 ) were used as soil cover. The residue of variety SP832847 was used upon four weed species: Brachiaria decumbens, B. brizantha, B. ruziziensis, and, B. humidicola. The experimental design was a randomized block with four replications. The weeds were sown 1 cm deep and covered by the residue. The seeding rate in use was 1,200 plants m -2 . The study was comprised of two phases: the first phase was an evaluation of plant emergence (more than 1 cm for shoots) at 9, 12, 19, 34 and 43 days after sowing (DAS), and in the second phase, plant emergence was evaluated after removal of the straw residue at 89, 130, 175, 196, 217

Management of superficial straw associate with strategy of physical improvement of the soil in the emergence of weeds

“…Thereby, only the data starting from the 0.02 to 0.07 m layer will be presented (Table 1) for characterizing the soil physical structure, superficially, and to establish relations with the weed emergence and the soil physical condition. Combined to this is the fact weed seeds in the soil are mainly concentrated in its superficial layer when under the no-till system (Silva et al, 2016). The non-significance of SD and TP along the soil profile is probably related to the absence of changes in these physical parameters, indicating that the mobilization by the shanks did not change such properties and there are no physical problems in the area.…”

“…This yield reduction in the area with rolled straw should be related to the soil physical state, which had a high soil area with resistance above 2.5 MPa (Figure 1C, D). In areas with low weed incidence, Silva et al (2016) mention that straw management does not influence the crop yield, only the cover decomposition speed and seed distribution in the soil. This disagrees with the data found in this study, probably due to the soil physical conditions that here show restrictive effects on plant development.…”

“…In a maize crop under NTS, the cover management prior to the sowing reduced weed infestation in accordance to the straw (Favarato et al, 2014). Rolling the black oat cover was more efficient, compared to non-rolling it, in suppressing the "capim-papauã" or plantain signal grass (Urochloa plantaginea) (Silva et al, 2016).…”

“…Besides the benefits related to the soil, this production system provides a reduced seed germination in photoblastic positive weeds (Silva et al, 2016). These advantages, when in association, result in increased crop yield and system sustainability (Qiu & Wang, 2018;Karayel & Šarauskiset, 2019).…”

Allelopathic Potential of Rice Cultivars Sowing in Santa Catarina State on Weedy Rice

“…This effect was expected because the soil cover plays an important role in the weed control, primarily due to the physical effect, which limits the passage of light, creating difficulties for the germination of the seeds (Pires et al, 2008), and through the barrier it forms, hindering the initial growth of seedlings, which is one of the main control methods (Guerra et al, 2015). Seeds of reduced size, such as weedy rice (Poaceae), are more susceptible to the physical effect of soil cover with straw (Monqueiro et al, 2011, Silva Jr. et al, 2016.…”