Reflectance of Cotton Leaves and Its Relation to Yield1

Abstract

A study was made of the effects of soil salinity, cotton leaf relative turgidity, and Cl content on reflectance and transmittance of radiation by single leaves. The relation of color film density to soil salinity, percentage ground cover, and cotton yield was also investigated. Reflectance from single leaves increased as soil salinity, leaf moisture deficit, and Cl content increased. Aerial photographs of field cotton on saline and nonsaline soils showed greater reflectance from cotton not affected by salt. (Kodak Ektachrome infrared aero film was used.) Multiple regression analyses indicated that under field conditions reflectance measured as film density was influenced by soil salinity and percentage ground cover. Since the same plant and soil factors that affect reflectance from the crop canopy also affect cotton yield, regression equations were calculated to express yield as a function of film density. The regression equations accounted for from 51 to 75% of the variation in yield.