Effects of water deficit and manganese toxicity on two cultivars of soybeans (Glycine max (L.) Merr.: Possible applications in remote sensing

Abstract

The effects of water deficit and excess Mn on leaf temperatures of two soybean cultivars were tested in greenhouse experiments on Mn toxic Loring soil. Cultivars used were Mn sensitive Forrest and Mn tolerant Lee. Water stress was created by withholding known amounts of water for a period of 12–24 hours. The untreated Loring soil produced Mn toxicity in Forrest but not in Lee. Hence, Mn was added as MnSO₄‐H₂O to induce toxicity in both cultivars; Mn treatments were 0 and 200 ug g‐1 for Forrest and 0 and 600 ug g‐1 for Lee. Both Mn and water stress increased leaf temperature. The interaction of water stress and Mn stress on leaf temperature could not be distinguished because both increased leaf temperature. Hence, under field conditions the detection of Mn induced leaf temperature change requires that water stress effects be eliminated. However, the effects of water stress on leaf temperature alone would be useful in assessing drought damage to crops. Since leaf temperature differences can be detected by remote sensing techniques, the results of this experiment will assist in the interpretation of remote sensing data.

Notes

Present Address: Science Applications International Corporation 400 Virginia Ave. S.W., Suite 810, Washington, DC 20024

Present Address: University of Maryland, Department of Geology, College Park, MD 20742