Competitividade De Espécies Forrageiras Do Campo Nativo Com Capim-Annoni Em Solo Com Diferentes Níveis De Adubação E Calagem

Abstract

A infestação de capim-annoni (Eragrostis plana Ness) nas áreas de pastejo em campo nativo ameaça a preservação do Bioma Pampa e a atividade pecuária no Rio Grande do Sul (RS). O objetivo deste trabalho foi avaliar a influência de tratamentos de adubação e calagem sobre a competitividade de espécies forrageiras do campo nativo com o capim-annoni, em área infestada pela invasora. Foi realizado um experimento em área de campo nativo infestada com capim-annoni no Centro de Pesquisa do DDPA/SEAPDR em Viamão – RS, sem uso de herbívoros domésticos, para avaliação do efeito dos tratamentos sem interferência do pastejo seletivo. Foram avaliados quatro tratamentos: T0 - sem adubação e calagem; T1 - apenas calagem; T2 - com adubação (nitrogênio, fósforo e potássio) e calagem; T3 - adubação com o dobro da dose de fósforo, mais potássio e calagem. Foram acompanhadas a evolução da composição botânica e o desenvolvimento das espécies do campo nativo e do capim-annoni por dois anos, através da avaliação da cobertura vegetal do solo e da produção de massa seca, como também as modificações da fertilidade do solo. Os resultados de produção de massa seca mostraram que a adubação nitrogenada do tratamento T2 beneficiou o crescimento do campo nativo e desfavoreceu o capim-annoni. Com a adubação nitrogenada do tratamento T2, espécies de gramíneas cespitosas do campo nativo atingiram maior altura e provavelmente competiram com o capim-annoni por meio de sombreamento, resultando na redução do crescimento da invasora.
 

Drought tolerance in tough lovegrass (Eragrostis plana): Understanding mechanisms and competitive ability

“…We observed an increase in root dry mass allocation under water deficit stress, reflecting the key drought avoidance strategy of biomass partition that allows roots to explore water reserves from deep-soil layers (Alou et al, 2018). Indeed, E. plana is characterized by a deep root system, as evidenced by its higher root biomass than native species (including P. notatum), at 0-40 cm soil depth (Abichequer et al, 2009), indicating its competitive advantage under water stress.…”

“…Rangeland pastures, such as those of southern Brazil, are characterised by a diversity of grass species with contrasting growth strategies (Marques et al, 2017); for example, the native C4 Paspalum notatum Flügge is used as a high quality forage species in areas of low precipitation in southern Brazil, due to its large and deep fibrous root system (Acuña et al, 2010). These drought avoidance characteristics, combined with high levels of root production (Abichequer et al, 2009), tolerance to low temperatures and high levels of seed production and viability (Medeiros et al, 2014), are shared between E. plana and P. notatum, likely leading to competition; however, a clear understanding of drought responses and associated interspecific competition between E. plana and P. notatum remains lacking. Thus, the aim of this study was to test for competitive differences in tolerance to drought conditions in the invasive species E. plana and the forage species P. notatum, due to variation in morphological, physiological, and biochemical trait responses to contrasting levels of water deficit.…”

Biology of the invasive species Eragrostis plana in Southern Brazil: What have we learned and how may this help us manage it?

“…Tillering is the stage most tolerant to water deficit, measured in terms of stomatal conductance and relative leaf water content (Bastiani et al, 2024). The root system is deep (up to 40 cm) and highly developed (Abichequer et al, 2009;Reis Leite, 1993), and under water stress, dry mass allocation to the root increases (Bastiani et al, 2024). This species can increase antioxidant system activity even under moderate stress, preventing reactive oxygen species accumulation, and, as stress abates, the plant rapidly induces osmolyte production to recover (Bastiani et al, 2024).…”

“…An extensive and deep root system is critical to E. plana competition because it helps access water and nutrients (Abichequer et al, 2009).…”

“…In addition, applying 200 kg of N ha −1 , 190 kg ha −1 of P 2 O 5 , and 140 kg ha −1 of K 2 O contributed to enhancing Pangola grass ( Digitaria eriantha ) growth and reducing E. plana growth, promoting a higher control index (Faleiro et al, 2021). In another study, liming and fertilisation, as recommended for pastures in Southern Brazil, favoured native grass and stunted E. plana growth, promoting higher native grass species height, resulting in ground shading and reducing invasive species growth (Abichequer et al, 2022). In areas outside native grasslands, where the invasive species also occurs, growing forage in winter followed by a crop (soybean, rice) in summer, reduced E. plana expansion, as shown in a soil seed bank assessment (Lamego et al, 2020).…”