Effect of RotyIenchulus reniformis on Reflectance of Cotton Plant Leaves


  • H. W. Gausman
  • C. M. Heald, Jr.
  • D. E. Escobar


Differences between light reflectance from leaves of cotton (Gossypiurn hirsutum) plants grown with a low- or no-nematode (Rotylenchulus reniformis) population (nonstressed), and from leaves grown with a high nematode population (stressed) were measured in field and greenhouse experiments. Reflectance was measured spectrophotometrically in the laboratory on single leaves and spectroradiometrically in the field on plant canopies. Nematode-stressed cotton plants were stunted with fewer, smaller, and darker-green leaves than nonstressed plants. Over the 0.5- to 2.5-/[mu]m waveband, stressed leaves had lower reflectance than nonstressed leaves of the same chronological age for both field- and greenhouse-grown plants. Reflectance differences between stressed and nonstressed leaves in the visible (0.5 to 0.75 [mu]m), near-infrared (0.75 to 1.35 [mu]m) and infrared water absorption (1.35 to 2.5 [mu]m) regions were primarily caused by differences in leaf chlorophyll concentration, mesophyll structure, and water content, respectively. Results indicate the potential for remotely sensing nematode-infested plants to distinguish them from normal plants. Key words: stressed and nonstressed leaves, remote sensing, chlorophyll content.