Balancing trade-offs: Enhanced carbon assimilation and productivity with reduced nutritional value in a well-watered C₄ pasture under a warmer CO₂-enriched atmosphere

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Habermann, Eduardo ; de Oliveira, Eduardo Augusto Dias ; Bianconi, Matheus Enrique ; Contin, Daniele Ribeiro ; Lemos, Maria Teresa Oliverio ; Costa, Joao Vitor Campos Pinho ; Oliveira, Kamilla Silva ; Riul, Beatriz Neroni ; Bonifacio-Anacleto, Fernando ; Viciedo, Dilier Olivera ; Approbato, Andressa Uehara ; Alzate-Marin, Ana Lilia ; Prado, Renato de Mello ; Costa, Katia Aparecida de Pinho ; Martinez, Carlos Alberto

• Tipo de documento: Artigo Científico
• Fonte: Plant Physiology and Biochemistry; v. 207, p. 13-pg., 2024-02-16.

Resumo

The concentration of atmospheric CO2 and temperature are pivotal components of ecosystem productivity, carbon balance, and food security. In this study, we investigated the impacts of a warmer climate (+2 degrees C above ambient temperature) and an atmosphere enriched with CO2 (600 ppm) on gas exchange, antioxidant enzymatic system, growth, nutritive value, and digestibility of a well-watered, managed pasture of Megathyrsus maximus, a tropical C-4 forage grass, under field conditions. Elevated [CO2] (eC) improved photosynthesis and reduced stomatal conductance, resulting in increased water use efficiency and plant C content. Under eC, stem biomass production increased without a corresponding increase in leaf biomass, leading to a smaller leaf/stem ratio. Additionally, eC had negative impacts on forage nutritive value and digestibility. Elevated temperature (eT) increased photosynthetic gains, as well as stem and leaf biomass production. However, it reduced P and K concentration, forage nutritive value, and digestibility. Under the combined conditions of eC and eT (eCeT), eT completely offset the effects of eC on the leaf/stem ratio. However, eT intensified the effects of eC on photosynthesis, leaf C concentration, biomass accumulation, and nutritive value. This resulted in a forage with 12% more acid detergent fiber content and 28% more lignin. Additionally, there was a decrease of 19% in crude protein leading to a 15% decrease in forage digestibility. These changes could potentially affect animal feeding efficiency and feedback climate change, as ruminants may experience an amplification in methane emissions. Our results highlight the critical significance of conducting multifactorial field studies when evaluating plant responses to climate change variables. (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: 20/16359-1 - Aclimatação, fluxo de carbono e emissão de gases estufa em pastagens de Brachiaria brizantha cv. Marandu e Brachiaria Mavuno inoculadas com Azospirillum brasilense sob atmosfera aquecida em condições de campo
• Beneficiário: Eduardo Habermann
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• 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: 14/00317-7 - 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