Spectra of Normal and Nutrient-Deficient Maize Leaves

Reflectance, transmittance and absorptance spectral of "normal" and six types of nutrient-deficient (N, P, K, S, Mg, and Ca) maize (Zea mays L.) leaves were analyzed at 30 selected wavelengths from 500~2600 nm. The analysis of variance showed significant differences in reflectance, transmittance and absorptance in the visible wavelengths among leaf numbers 3, 4, and 5, among the seven treatments, and among the interactions of leaf number and treatments. In the infrared wavelengths only treatments produced significant differences. The chlorophyll content of leaves was reduced in all nutrientdeficient treatment s. Percent moisture 'was increased in S-, Mg-, and N-deficiencies. Positive correlations were obtained (r = 0.7) between moisture content and percent absorption at both 1450 and 1930 nm. Polynomial regression analysis of leaf thickness and leaf moisture content showed that these two variables were significantly and directly related (R = 0.894). Leaves from the Pand Ca-deficient plants absorbed less energy in the near infrared than the normal plants; S-, Mg-, K-, and N-deficient leaves absorbed more than the normal. Leaf thermo grams were prepared on normal and Sand Ndeficient leaves. Both Sand N-deficient leaves had higher temperatures than normal maize leaves. IJournal Paper No. 4839, Purdue University Agricultural Experiment Station. Supported by: U.S.D.A. Contract #12-14-100-10292 (20), NASA Grant NGR 15-005-1'12, N. S. F. Grant GB5701, National Institute of General Medical Science Career Grant K6-2l839, and Training Grant GM01392. 2Research Agronomist, Research Associate, Former Graduate Assistant , Professor of Biology, and Associate Professor of Agronomy.