Crushed, Squeezed, or Pressed? How Extraction Methods Influence Sap Analysis

Sap analysis provides a fast and promising approach to diagnosing plant nutritional status, yet methodological gaps remain a crucial obstacle to widespread adoption. Understanding how different extraction methods influence sap composition is key to improving the consistency and diagnostic reliability of this technique. Therefore, five methods were compared based on a range of chemical and physical parameters of broccoli petiole sap. Multiple statistical approaches were used to evaluate method effects on individual parameters and their inter-relationships. Extraction method significantly influenced chemical profiles—altering means, variability and distributional shapes—whereas physical attributes varied less across methods. Relationships among traits were observed; however, the consistency of patterns varied depending on the method. Overall, these results suggest that refining method selection could enhance both diagnostic reliability and the depth of interpretive analysis. This calls for rethinking current sap analysis practices, raising awareness of methodological variability and encouraging the development of robust, standardized approaches for reliable and comparable sap-based diagnostics.