Productivity, Control, and Decomposition of Irrigated Forage Species under Glyphosate Doses and Shading

Abstract

Light intensity available in growing environments may influence the susceptibility of plants to glyphosate and decomposition of their residues. This study aimed to assess the productivity, control, and decomposition of forage straw submitted to glyphosate doses and exposed to full sun and 50% shade. Two experiments were carried out, one for Piatã grass (Urochloa brizantha cv. Piatã) and other for Tanzania grass (Megathyrsus maximus cv. Tanzania). The experimental design was a randomized block design with strip-plot and four replications. Two growing environments (at full sun and under 50% shade) were installed in strips in the growing area, combined with six doses of glyphosate (0, 360, 720, 1,080, 1,440, and 1,800 g a.e. ha-1) used for forage desiccation. Shade did not change Tanzania grass productivity (p<0.05), but it reduced Piatã grass productivity (p>0.05), suggesting its low tolerance to light restriction. Tanzania grass is more tolerant to glyphosate when compared to Piatã grass, especially at full sun conditions. In general, the evaluated forages present a high susceptibility to glyphosate as incident radiation is reduced, which allows using lower doses to desiccate them in shaded environments. Straw decomposition of Piatã and Tanzania grasses was slower under shading. In this environment with light restriction, straw is more durable and has a better quality for the no-tillage system.

Luminous restriction and chemical control with glyphosate in integrated management of Urochloa brizantha L.

“…The higher sensitivity of U. brizantha and Meghatirsus maximus to glyphosate in an environment with 50% light restriction, compared to plants kept in full sun, was reported Brant et al (2018). The higher sensitivity to glyphosate by weeds grown in shaded environments, compared to plants kept in full sun, was also observed for Commelina benghalensis , Macroptilium atropurpureum (Costa et al, 2020), Cyperus rotundus , Merremia cissoides (Ferreira et al, 2022a), and for Euphorbia heterophylla (Ferreira et al, 2022b) corroborating what was found in the present study.…”

“…Research, Society and Development, v. 11, n. 17, e177111738758, 2022 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10. 33448/rsd-v11i17.38758 This research study innovates in relation to Brant et al (2018) for testing intermittent shading in simulation of what happens in field conditions with shading by other larger species. Studies on the response of plants to light restriction use the shade of trees in cultivation environments (Santos et al, 2017), or artificial shading with sombrite (Parissi and Koukoura, 2009;Martins et al, 2014, Costa et al, 2020, Brant et al 2018, Ferreira et al, 2022a.…”

“…33448/rsd-v11i17.38758 This research study innovates in relation to Brant et al (2018) for testing intermittent shading in simulation of what happens in field conditions with shading by other larger species. Studies on the response of plants to light restriction use the shade of trees in cultivation environments (Santos et al, 2017), or artificial shading with sombrite (Parissi and Koukoura, 2009;Martins et al, 2014, Costa et al, 2020, Brant et al 2018, Ferreira et al, 2022a. However, these two types of light restriction differ in light incidence since, in natural conditions, there is an alternation between direct and diffuse radiation that affects the understory, which does not occur in artificial shading.…”

“…It is estimated that in Brazil alone, more than 60 million hectares are planted with this species due to the high adaptation to climatic conditions and high productivity of biomass and seeds (Duarte et al, 2019;Santos et al, 2007). With the growth in the last decade of no-tillage and integrated production systems, its use has become even more widespread (Brant et al, 2018). U. brizantha also compose integrated production systems such as intercropping in consortium with coffee, fruit, and timber species (Pedrosa et al, 2014;Fidalski et al, 2009;Santos et al, 2017), requiring its control for production of straw either for direct planting or as soil cover.…”

Urochloa brizantha E Andropogon gayanus EM MONOCULTIVO E CONSÓRCIO SOB DIFERENTES NÍVEIS DE ADUBAÇÃO

“…A decomposição rápida da palhada de algumas espécies pode colocar o solo a uma exposição por maior tempo, ainda mais, quando as regiões apresentam condições edafoclimáticas como temperatura, luminosidade, clima e pluviosidade, acelerando esse processo. Sendo assim, recomenda-se a aplicação de espécies que tenham uma taxa de decomposição mais lenta, que por consequente aumentará a eficiência da cobertura do solo (BRANT et al;.…”