MEASUREMENT OF LEAF RELATIVE WATER-CONTENT BY INFRARED REFLECTANCE

From basic considerations and Beer's law, a leaf water content index incorporating reflectances of wavelengths from 0. 76 to 0. 90 mu m and from 1. 55 to 1. 75 mu m (Landsat Thematic Mapper Bands TM4 and TM5, respectively) was developed that relates leaf reflectance to leaf relative water content. For the leaf succulent, Agave deserti, the leaf water content index was not significantly different from the relative water content for either individual leaves or an entire plant. Thus, the leaf water content index may be able to estimate average relative water content of canopies when TM4 and TM5 are measured at a known relative water content and fraction of dead leaf material.