Spectral Properties of Soybean Leaves1

Abstract

AbstractLight transmission and reflection by leaves are dependent on leaf pigmentation, morphology, and internal structure, all of which may be different in different ages and varieties of soybean leaves. These differences were measured and characterized in the hope that they would prove to be useful in varietal identification by remote sensing techniques.The reflectance and transmittance of three varieties of soybean leaves were measured over a wavelength range from 500 to 2500 nm using a ratio recording spectroreflectometer. Spectral characteristics of soybean leaves as affected by leaf age were determined. Reflection and absorption of light incident on the upper surfaces (faces) were compared with that of the lower surfaces (backs) of the same leaves. The spectral characteristics of three varieties of soybeans did not differ very much except in the visible region of the spectrum studied. Relatively young leaves reflected more than did old leaves of the same variety in the visible. This was associated with the chlorophyll development. The upper surface reflected less than did the lower surface of the same leaves in the visible region. Such differences were explained on the basis of internal leaf structure and composition.Although the spectral properties of the three soybean varieties have been established, it was not possible to make varietal identification on the basis of the spectral qualities.