Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Physical Nature of Irreversible Deformation of Plant Cells

James A. Lockhart
Plant Physiology
Vol. 42, No. 11 (Nov., 1967), pp. 1545-1552
Stable URL: http://www.jstor.org/stable/4261194
Page Count: 8
  • Read Online (Free)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Physical Nature of Irreversible Deformation of Plant Cells
Preview not available

Abstract

Etiolated mung bean hypocotyl segments were incubated in 0.25 M mannitol solutions with indoleacetic acid. They were then deformed mechanically with a longitudinal tensile force at a constant strain rate. The magnitudes of the mechanical forces were comparable to those of the hydrostatic forces existing in normally growing tissues. Each segment was repeatedly deformed and returned to zero force. The total deformation was increased at each cycle. The irreversible and elastic changes in length and diameter were measured for each deformation and the changes in surface area and volume calculated. In addition the applied stress and the work of irreversible and of elastic deformation were determined as functions of deformation. It was found that irreversible elongation, irreversible change in surface area and total change in surface area all were linear functions of total imposed elongation. However, very little change in volume occurred during the deformations. The work of irreversible deformation was found to be independent of temperature between 8° and 25°. It was also virtually independent of rate of deformation measured over a 5-fold range of deformation rates. From these results it is concluded that the irreversible deformation of mung bean hypocotyl tissue occurs by plastic deformation rather than by viscous flow. Thus, the irreversible deformation occurred as a result of breaking cross-links of a cross-linked polymer system.

Page Thumbnails

  • Thumbnail: Page 
1545
    1545
  • Thumbnail: Page 
1546
    1546
  • Thumbnail: Page 
1547
    1547
  • Thumbnail: Page 
1548
    1548
  • Thumbnail: Page 
1549
    1549
  • Thumbnail: Page 
1550
    1550
  • Thumbnail: Page 
1551
    1551
  • Thumbnail: Page 
1552
    1552