CO₂ enrichment in protected agriculture has been extensively studied as a strategy to enhance crop productivity, resource use efficiency, and climate resilience. This systematic review examines the scientific literature on CO₂ enrichment in greenhouses, vertical farms, and controlled environment agriculture (CEA) systems, with a focus on its impact on crop physiology, photosynthesis, agricultural yield, modeling and simulation techniques, injection technologies, and sustainability challenges. A comprehensive bibliometric and systematic search was conducted in the Scopus database using key terms related to CO₂ enrichment and sustainable protected agriculture, following the PRISMA methodology. From an initial set of 212 documents, 171 were selected after removing duplicates, inaccessible articles, and studies not directly relevant to this context. The findings indicate that CO₂ enrichment can significantly improve photosynthetic efficiency, water use efficiency, and crop productivity, although its impact varies depending on species, environmental conditions, and application strategies. Computational models, such as CFD and machine learning, have optimized CO₂ distribution in controlled environments, contributing to more precise and resource-efficient agricultural practices. However, environmental and economic concerns, particularly energy consumption, carbon footprint, and the sustainability of CO₂ sources, remain critical challenges. To ensure the sustainable adoption of CO₂ enrichment, it is essential to integrate renewable energy sources, carbon capture and reuse technologies, and advanced CO₂ injection systems. This review provides a holistic assessment of current knowledge, identifying opportunities and barriers for the development of climate-smart protected agriculture systems that align with global sustainability goals and contribute to food security and environmental stewardship.

This study addresses solar energy applications in protected agriculture, focusing on greenhouses and related technologies. A bibliometric and technical analysis is developed, covering research published between 1976 and 2024, to identify the main trends and challenges in the use of solar energy in controlled environments. The methodology was based on the PRISMA approach, using the Scopus database to retrieve relevant documents. From an initial total of 221 documents, 216 were selected after a filtering and debugging process, ensuring the relevance of the final set. In the analytical phase, the results showed a moderate growth of 3.68% in the annual publication rate, highlighting the impact of research on solar energy’s application to air conditioning and energy efficiency in greenhouses. Most of the studies reviewed feature hybrid systems that combine solar energy with other resources, and we highlight both advances in climate control through artificial intelligence and the implementation of photovoltaic and thermal technologies to improve the energy efficiency of agricultural systems. The results also underline the importance of tomato cultivation in the selected studies, reflecting its global economic impact. The conclusions highlight the need for the further integration of energy storage and desalination technologies, especially in arid regions with high solar irradiation, to ensure the sustainability of greenhouses. It is proposed that future research should address the wider implementation of hybrid systems and advanced climate control technologies, optimizing both the use of energy resources and the performance of crops under cover. In addition, it is recommended that international collaboration be strengthened to address technical and climatic challenges in protected agriculture and to expand the adoption of innovative solutions in different geographical contexts.

CO₂ enrichment in protected agriculture is a key strategy for enhancing crop productivity and quality, optimizing photosynthetic efficiency, and mitigating the impacts of climate change. In this study, a comprehensive bibliometric analysis of research on CO₂ enrichment is conducted by compiling and evaluating 171 relevant documents published between 1982 and 2024 in Scopus, utilizing R-Studio and VOSviewer for data processing. The analysis explores scientific output trends, predominant research methodologies, influencing factors, and emerging applications in controlled-environment agriculture. The findings reveal an exponential growth in scientific publications since 2015, with Asia and Europe leading the research landscape. The physiological and agronomic benefits of CO₂ enrichment in C3 crops, particularly tomatoes and lettuce, include enhanced photosynthesis, improved nitrogen assimilation, and reduced abiotic stress. Additionally, advancements in sustainable CO₂ capture and delivery technologies, such as industrial capture and fermentation-based systems, have been documented. However, significant challenges remain regarding the economic feasibility, accessibility for small-scale farmers, and environmental sustainability of CO₂ enrichment strategies. A network analysis of scientific collaboration highlights an increasing trend of international cooperation, with China, the United States, and Japan emerging as key contributors. The integration of plant physiology, agricultural engineering, and environmental sustainability reflects a transition toward multidisciplinary approaches aimed at optimizing CO₂ utilization in controlled environments. This study underscores the potential of CO₂ enrichment as a transformative tool in protected agriculture. However, its large-scale adoption necessitates international collaboration, rigorous research on socio-economic and environmental impacts, and the development of context-specific technologies. Strengthening global research networks and fostering applied innovation will be essential to ensuring the widespread and sustainable implementation of CO₂ enrichment strategies in protected agriculture.