Warming offsets the benefits of elevated CO2 in water relations while amplifies elevated CO2-induced reduction in forage nutritional value in the C-4 grass Megathyrsus maximus

Autor(es)

Habermann, Eduardo ; de Oliveira, Eduardo Augusto Dias ; Contin, Daniele Ribeiro ; Costa, Joao Vitor Campos Pinho ; Costa, Katia Aparecida de Pinho ; Martinez, Carlos Alberto

• Tipo de documento: Artigo Científico
• Fonte: FRONTIERS IN PLANT SCIENCE; v. 13, p. 15-pg., 2022-12-05.

Resumo

Tropical grasslands are very important to global carbon and water cycles. C-4 plants have increased heat tolerance and a CO2 concentrating mechanism that often reduces responses to elevated concentrations of CO2 ([CO2]). Despite the importance of tropical grasslands, there is a scarcity of studies that elucidate how managed tropical grasslands will be affected by elevated [CO2] and warming. In our study, we used a combination of a temperature-free air-controlled enhancement (T-FACE) and a free-air carbon dioxide enrichment (FACE) systems to increase canopy temperature and [CO2] under field conditions, respectively. We warmed a field-grown pasture dominated by the C-4 tropical forage grass Megathyrsus maximus by 2 degrees C above ambient under two levels of [CO2] (ambient (aC) and elevated (eC - 600 ppm) to investigate how these two factors isolated or combined regulate water relations through stomatal regulation, and how this combination affects PSII functioning, biochemistry, forage nutritive value, and digestibility. We demonstrated that the effects of warming negated the effects of eC in plant transpiration, water potential, proline content, and soil moisture conservation, resulting in warming canceling the eCO(2)-induced improvement in these parameters. Furthermore, there were additive effects between eC and warming for chlorophyll fluorescence parameters and aboveground nutritive value. Warming sharply intensified the eCO(2)-induced decrease in crude protein content and increases in forage fibrous fraction and lignin, resulting in a smaller forage digestibility under a warmer CO2-enriched atmosphere. Our results highlight the importance of multifactorial studies when investigating global change impacts on managed ecosystems and the potential consequences for the global carbon cycle like amplification in methane emissions by ruminants and feeding a positive climate feedback system. (AU)

• Processo FAPESP: 08/58075-8 - Miniface climate-change impact experiment to analyze the effects of elevated CO2 and warming on photosynthesis, gene expression, biochemistry, growth, nutrient dynamics and yield of two contrasting tropical forage species
• Beneficiário: Carlos Alberto Martinez y Huaman
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Temático
• Processo FAPESP: 16/09742-8 - Relações hídricas, trocas gasosas, anatomia foliar e análises termográficas de duas espécies forrageiras sob aquecimento e deficiência hídrica em condições de campo
• Beneficiário: Eduardo Habermann
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 14/26821-3 - Análise comparativa das relações hídricas em espécies forrageiras C3 e C4 submetidas a elevado nível de CO2 e aquecimento em sistema TROP-T-FACE
• Beneficiário: Eduardo Habermann
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 14/00317-7 - Fluxo de carbono e de gases estufa em ecossistema de pastagem composta por Panicum maximum Jacq. e Stylosanthes capitata Voegel cultivadas sob elevada concentração de CO2 e elevada temperatura em sistemas FACE/T-FACE
• Beneficiário: Eduardo Augusto Dias de Oliveira
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado