Aumento da concentração de CO2 atmosférico e seus efeitos na interação planta daninha/cultura da soja
Carregando...
Data
2018-07-13
Autores
Santos, Jucileia Irian dos
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Até o final do século XXI, as projeções de mudanças climáticas baseadas na emissão de gases de efeito estufa sugerem aumento na concentração de dióxido de carbono atmosférico, em até 750 ppm. Se as projeções se realizarem, teremos alterações significativas no desenvolvimento vegetal e, consequentemente, nos sistemas agrícolas, alterando, portanto, as interações entre plantas daninhas e culturas. Em vista disso, o presente trabalho objetivou avaliar: (1) o efeito do incremento da concentração atmosférica de CO2 na interação entre plantas daninhas (Euphorbia heterophylla e Amaranthus viridis) e soja (Glycine max); (2) as características fisiológicas e bioquímicas dessas plantas em duas concentrações de CO2; e (3) a capacidade de competição através da absorção de nutrientes. Foram desenvolvidos três experimentos, em câmaras de topo aberto (OTCs). Nos dois primeiros experimentos, o delineamento experimental utilizado foi inteiramente casualizado, em esquema fatorial 5x2, sendo cinco condições de convivência (monocultura de soja, de caruru e de leiteiro, e convivência de soja com caruru e de soja com leiteiro) e duas concentrações de CO2 (400 e 800 ppm). No terceiro experimento, foi utilizado um esquema fatorial 2X5: duas concentrações de CO2 (400 e 800 ppm) e cinco épocas de avaliações (7, 14, 21, 35 e 50 dias após o transplante), sendo as espécies cultivadas separadamente sem coexistência. No primeiro experimento, os resultados demonstraram que o aumento de CO2 afetou diferentemente as três espécies, sendo que a interferência intraespecífica de soja e caruru foram maiores em 800 ppm, enquanto que de leiteiro foi maior em 400 ppm. A convivência da soja com caruru e da soja com leiteiro resultou em prejuízo mútuo, tanto para soja quanto para as plantas daninhas, no entanto, quando a soja se desenvolveu em convivência com leiteiro, a interferência interespecífica foi maior em 800 ppm. No segundo experimento, o incremento de CO2 resultou em maior assimilação de carbono pela fotossíntese somente em soja, no entanto, houve aumento na eficiência do uso da água e no teor de carotenoides, para as três espécies estudadas. De forma geral, o incremento de CO2 atmosférico reduziu o teor de malondialdeído em soja, caruru e leiteiro, no entanto maior atividade da enzima SOD foi observada nessas três espécies. O perfil metabólico foi modificado em decorrência do aumento da concentração de CO2, sendo que condição ambiente apresentou maior teor de sacarose, enquanto que plantas em elevado CO2 apresentaram maior teor de glicose. Já em relação ao metabolismo secundário, a soja e o leiteiro apresentaram maior síntese de compostos flavonoides em elevado CO2, enquanto que o caruru apresentou redução do flavonoide rutina.
By the end of the 21st century, climate change projections based on the emission of greenhouse effect gases suggest an increase in the concentration of atmospheric carbon dioxide, in up to 750 ppm. In this scenario, we have significant changes in plant development, and consequently, in agricultural systems, thus altering the interactions between crops and weeds. Based on that, the aims of this work were to evaluated the effect of increasing of atmospheric CO2 concentration on the interaction between weeds (Euphorbia heterophylla and Amaranthus viridis) and soybeans (Glycine max), and the physiological and biochemical characteristics of these plants at two concentrations of CO2. Two experiments were carried out in open-top chambers (OTCs), in a completely randomized experimental design in a 5x2 factorial scheme: five coexistence conditions (monoculture of soybean, Slender Amaranth and wild poinsettia, and coexistence of soybean with Slender Amaranth and soybean with wild poinsettia) and two concentrations of CO2: 400 and 800 ppm. In the first experiment, the results showed that the increase of CO2 was different on the three species, and the intraspecific interference of soybean and slender amaranth was higher in 800 ppm, while in wild poinsettia the intraspecific interference was higher in 400 ppm. The coexistence of soybeans with slender amaranth and soybeans with wild poinsettia resulted in mutual injury, for both soybean and for weeds, however, when soybean was developed in coexistence with wild poinsettia, interspecific interference was higher in 800 ppm. In the second experiment, increase of CO2 resulted in greater carbon assimilation by photosynthesis only in soybeans, however, there was increase in the water use efficiency and in the carotenoid content, for the three species. In general, the increase of atmospheric CO2 reduced the lipid peroxidation in soybean, slender amaranth and wild poinsettia, but a greater activity of the SOD enzyme was observed in these three species. The metabolic profile was changed by the higher CO2 concentration, wherein at 400 ppm presented higher sucrose content, while plants 800 ppm presented higher glucose content. The secondary metabolism of soybean and wild poinsettia presented a higher synthesis of flavonoid compounds at 800 ppm, while slender amaranth showed decrease of flavonoid rutin.
By the end of the 21st century, climate change projections based on the emission of greenhouse effect gases suggest an increase in the concentration of atmospheric carbon dioxide, in up to 750 ppm. In this scenario, we have significant changes in plant development, and consequently, in agricultural systems, thus altering the interactions between crops and weeds. Based on that, the aims of this work were to evaluated the effect of increasing of atmospheric CO2 concentration on the interaction between weeds (Euphorbia heterophylla and Amaranthus viridis) and soybeans (Glycine max), and the physiological and biochemical characteristics of these plants at two concentrations of CO2. Two experiments were carried out in open-top chambers (OTCs), in a completely randomized experimental design in a 5x2 factorial scheme: five coexistence conditions (monoculture of soybean, Slender Amaranth and wild poinsettia, and coexistence of soybean with Slender Amaranth and soybean with wild poinsettia) and two concentrations of CO2: 400 and 800 ppm. In the first experiment, the results showed that the increase of CO2 was different on the three species, and the intraspecific interference of soybean and slender amaranth was higher in 800 ppm, while in wild poinsettia the intraspecific interference was higher in 400 ppm. The coexistence of soybeans with slender amaranth and soybeans with wild poinsettia resulted in mutual injury, for both soybean and for weeds, however, when soybean was developed in coexistence with wild poinsettia, interspecific interference was higher in 800 ppm. In the second experiment, increase of CO2 resulted in greater carbon assimilation by photosynthesis only in soybeans, however, there was increase in the water use efficiency and in the carotenoid content, for the three species. In general, the increase of atmospheric CO2 reduced the lipid peroxidation in soybean, slender amaranth and wild poinsettia, but a greater activity of the SOD enzyme was observed in these three species. The metabolic profile was changed by the higher CO2 concentration, wherein at 400 ppm presented higher sucrose content, while plants 800 ppm presented higher glucose content. The secondary metabolism of soybean and wild poinsettia presented a higher synthesis of flavonoid compounds at 800 ppm, while slender amaranth showed decrease of flavonoid rutin.
Descrição
Palavras-chave
Incremento de CO2 atmosférico, Mudança climática, Interferência, Perfil metabólicos de plantas daninhas