Extraction of cucumber phloem sap based on the capillary–air pressure principle

Changes in the substances in phloem sap can effectively reflect the nutritional status of cucumber plants during their growth. Because of the limitations of the time-consuming and complex operations of existing phloem sap extraction methods, the authors proposed a new extraction method based on the capillary-air pressure principle and designed a new sap sampling device. To examine the feasibility of the new sampling device, sap sampled from the same plant with the new method and the common EDTA method was analyzed by gas-phase mass spectrometry. The data showed that the number of substances in the sap sampled using capillary–air pressure was higher than that observed using the EDTA method. The concentration of substances sampled using capillary–air pressure was much higher than that observed using EDTA.