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This article in AJ

  1. Vol. 84 No. 4, p. 618-621
    Received: July 25, 1991

    * Corresponding author(s):
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Scanning Electron Microscopy for Studying Root Morphology and Anatomy in Alfalfa Autotoxicity

  1. Ramesh S. Hegde and
  2. D. A. Miller 
  1. Dep. of Agronomy, 1102 S. Goodwin Ave., Univ. of Illinois, Urbana, IL 61801.



The aqueous extract of alfalfa (Medicago sativa L.) shoots inhibits root elongation, shoot elongation, and/or germination of alfalfa itself-a phenomenon termed autotoxicity. The study of the mode of action of allelopathic and/or autotoxic compounds at the plant organ and cellular levels is limited by the depth of field, resolution, and magnification of a light microscope compared to a scanning electron microscope. Scanning electron microscopy techniques were used to study the morphology and anatomy of the roots inhibited by the water-extract of alfalfa shoots. Investigations on the morphology of shoot-aqueous-extract-inhibited, 5-d old ‘WL-316’ alfalfa roots revealed a 46% reduction in density and 54% reduction in length of root hairs compared to the control. Anatomical differences between the inhibited and uninhibited alfalfa roots were also observed. Shoot aqueous extract did not cause clogging of xylem vessels. The scanning electron microscope is a valuable tool in the study of the mode of action of allelopathic or autotoxic compounds at the plant organ as well as cellular levels.

Part of the thesis of the senior author submitted to the Univ. of Illinois in partial fulfillment of the requirements for the degree of doctor of philosophy in agronomy.

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