THEORIES OF ASCENT OF SAP

ASCENT OF SAP
  • Sap is a liquid containing water and dissolved mineral salts. The upward movement of water from the root system to the aerial parts of the plant through the xylem is known as ascent of sap. Xylem is the main water conducting tissue and the ascent of sap take place through the xylem.
  • The ringing experiment of Malphigi proved that ascent of sap takes place through xylem. A ring of bark (all tissues outside the xylem) is removed from the stem and the plant is left as such for a few days. The leaves above the ringed part of the stem remain fresh and green.
  • This shows that the ascent of sap occurs through xylem. Similarly, if a portion of xylem is removed by making a hole in the stem, the leaves above that portion showed wilting symptom. This again confirms the ascent of sap is through xylem.
     

Last modified: Tuesday, 4 October 2011, 4:30 AM