Water and Air Changes in Grapefruit, Corn, and Cotton Leaves with Maturation1

Abstract

AbstractRecent progress in remote sensing of agricultural areas from aircraft and spacecraft has motivated new research in the basic understanding of the interaction of light with plant leaves. Many plant leaves can be simulated by a transparent plate model with rough plane‐parallel surfaces. A plant leaf can be specified in this model by two optical parameters associated with an imaginary index of refraction and two parameters that represent the geometrical configuration of the internal leaf structure. The model leads to determination of water and air in a leaf by non‐destructive procedures. Previous work that reported on maturation of cotton leaves grown hydroponically in a growth chamber has been extended to leaves of potted grapefruit seedlings, field‐grown corn, and field‐grown cotton plants. Significant differences are observed between the measured water in a leaf and the equivalent water thickness (EWT) calculated from spectrophotometric measurements. The EWT is about 15% greater than the thickness of water that can be removed from the leaf by oven drying at 68 C for 72 hours. Measures of the intercellular air spaces in the leaves are in general agreement with previous results except that the corn leaves are not as compact as expected.