Global food production must meet the dietary requirements of a growing population, which is expected to reach 8–11 billion by 2100, while reducing the environmental impact of agricultural practices. The agricultural sector accounts for 21–37% of global greenhouse gas emissions, 70% of freshwater, and contributes considerably to biodiversity loss and challenges that are further intensified by climate change. Controlled Environment Agriculture (CEA) serves as a sustainable strategy to address global food production and promote consistency and resource-efficient crop production. However, nutrient imbalances remain a key challenge in hydroponic CEA systems. To address these nutrient-related challenges, plant sap analysis is being considered as real-time monitoring tool and precise nutrient management in CEA systems. Compared to traditional nutrient tissue analysis, sap analysis shows stronger correlations with crop performance during active growth. For instance, petiole sap nitrate-nitrogen (NO3−-N) and total nitrogen (N) in tomato leaves show correlation coefficients of r = 0.6–0.8 during their rapid vegetative growth stages. Sap analysis shows potential improvements in nutrient efficiency, crop quality, and sustainability within CEA. This review investigates the principles, methodologies, and advancements in plant sap analysis, contrasting it with traditional nutrient testing methods. It also addresses challenges such as variability in sap composition, the lack of standardized protocols, and economic considerations, while emphasizing real-time nutrient management to achieve and sustainability in CEA.
Rauf et al. (2025) studied this question.