Resposta de azevém (Lolium multiflorum Lam.) à elevada concentração atmosférica de CO2 e da aplicação de herbicidas

Abstract

In the south of Brazil, the Italian ryegrass stands out as a soil cover crop and as an important forage, especially in lowlands. On the other hand, in agricultural crops it is considered a weed, being problematic in the pre-sowing of soybeans and rice showing resistance to herbicides. In addition, studies mention that this species has allelopathic compounds that suppress weeds that can also harm the emergence of rice seedlings (Oryza sativa L.), which is one of the main cereals present in human food. There is a concern about how this species will behave in the face of global climate changes and how it will affect its positive and negative aspects, making it necessary to know how the plants respond physiologically and phenotypically to the increase in the concentration of atmospheric CO2. Thus, this work aimed to: evaluate phenotypic changes and the effects on the growth and reproduction of Italian ryegrass (Lolium multiforum Lam.) Grown in an atmosphere with a high concentration of CO2 (700 ppm), as well as, to investigate the allelopathic effect of Italian ryegrass plants dried with herbicides, in the subsequent sowing of rice in succession with pasture. For this, experiments were conducted in Open Top Chambers (OTC) where the Italian ryegrass and rice plants were grown with two concentrations of CO2 400 ppm (current) and 700 ppm (2050 climate change scenario). The results show that Italian ryegrass plants grown in high CO2 concentration show an increase in tillering and vegetation cover, however, less height, and a reduction in the quantity of grains produced, without altering the nutritional quality of the forage. In relation to interaction with herbicides used in desiccation for the seed of irrigated rice, or glufosinate in desiccation of azevem cultivated in high CO2 reduced to germination of rice seed.