Physiological and productive performance of forages Brachiaria brizantha cv Marandu inoculated with Azospirillum brasilense and subjected to warming in a future climate simulation experiment

• Grant number: 23/18208-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): March 01, 2024
• Effective date (End): December 31, 2024
• Field of knowledge: Biological Sciences - Botany - Pant Physiology
• Principal Investigator: Carlos Alberto Martinez y Huaman
• Grantee: Luiza Beraldi Gallo
• Host Institution: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Climate change and its effects are the biggest environmental challenges we face today. More frequent and more intense extreme weather events, such as droughts, floods and heatwaves, which significantly impact food production, are recent evidence of climate change. There are two approaches to tackling climate change: Adaptation, developing ways to live with climate change by adjusting to the current and future climate scenario, and Mitigation, reducing the effects of climate change by reducing greenhouse gas emissions into the atmosphere. In Brazil, around 90% of beef cattle are raised on pasture. Four of the seven programs of the Brazilian Low Carbon Agriculture Plan (ABC Plan), the recovery of degraded pastures, biological nitrogen fixation, Crop-Livestock-Forest integration and adaptation to climate change, are related to pastures and their management. In this proposal, we intend to generate a scientific basis for better pasture management and contribute to the ABC plan. We will study the effects of heating (increasing the plant's temperature by +2°C) and inoculation with two strains of nitrogen-fixing bacteria: Azospirrillum brasilense: CNPSo 2083 and CNPSo 2084, developed by EMBRAPA, on the physiological performance of the forage grass: Brachiaria brizantha cv Marandu. Physiological and yield parameters of the forage will be assessed. The T-FACE (Temperature free-air controlled enhancement) system will be used to increase the plant's canopy temperature by +2°C in a future climate simulation experiment. Our hypothesis is that Brachiaria plants inoculated with N-fixing bacteria show better physiological performance than non-inoculated plants, all year round, including at high temperatures in the dry and rainy seasons. The proposed hypothesis is plausible because there is strong evidence that in inoculated grasses, in addition to fixing N from the air, the Azospirillum bacteria also stimulate root growth, maintaining plant productivity even in conditions of scarce water availability. The proposal will continue the research into the impacts of climate change on tropical forage species carried out at USP/RP, São Paulo, using the T-FACE system. This proposal will have a significant scientific and environmental impact, as it will suggest solutions regarding the use of nitrogen fixation to adapt C4 forage grasses to dry and rainy season heating. Solutions related to mitigation will also be considered, as the use of biological N fixation through bacteria will make it possible to reduce the use of nitrogen fertilizers and thus reduce N2O emissions. This study will also have an important social and economic impact, as we will study the performance of Brachiaria brizantha cv Marandu, which is widely used in Brazilian livestock farming, in responding to warming. The results of the research will be disseminated as a scientific article and lectures to the community, as well as to farmers using different media in appropriate language, highlighting the relevance of the results to society.