Effects of Defoliation, Deradication, and Darkening the Blade upon Translocation of C14 in Sugarcane

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Abstract
Actively growing lateral and basal shoots increase the percentage of downward translocation of photosynthetically-labeled sucrose made in a single blade. Roots exert no force attracting the translocate. Defoliation above or below the fed blade increases translocation to the stem, the removal of upper leaves having greater effect than the removal of lower leaves. Thus removal of competing streams increases translocation. Defoliation of all but the fed blade does not damage its ability to translocate; therefore, the pull of transpirationfrom the other leaves does not affect translocation. Cutting off the fed blade above the fed part, or darkening the fed blade with foil, or both treatments (after removing the feeding chamber) decreased translocation from the fed leaf resulting in an accumulation of labeled sucrose in the sheath; thus a major bottleneck in the translocation is at the attachment of the sheath to the stalk. Since translocation from a blade is increased by the removal of the other blades, and can take place well in a blade detached from the stalk, a major force of translocation is within the blade itself.