Degree Type

Dissertation

Date of Award

1989

Degree Name

Doctor of Philosophy

Department

Agronomy

First Advisor

J. H. Dekker

Second Advisor

T. W. Jurik

Abstract

The role of competition for light in interference between velvetleaf and soybean was evaluated at the whole plant and canopy levels in field and greenhouse studies conducted from 1986 to 1988 at Ames, Iowa. Analysis of deWit replacement series results indicated that interference between velvetleaf and soybean did not occur early in the growing season when individual plants were fairly widely separated. However, as canopy closure occurred, velvetleaf gained resources at the expense of soybean and, thereby, reduced the vegetative and reproductive growth of the crop. The presence of verticillium wilt disease in velvetleaf reduced its ability to interfere with soybean. Velvetleaf has several attributes that enhance its ability to compete with soybean for light. These include a rapid early growth rate; rapid, extensive stem growth which leads to a tall stature; and a branching pattern that situates much of the leaf area near the top of the plant, above the leaves of shorter competing species. Additionally, active leaf movements which improve the water use efficiency, light interception, and photosynthetic activity of velvetleaf (and concomitantly increase shading of associated shorter species) also contribute to its greater ability to compete for light.

DOI

https://doi.org/10.31274/rtd-180813-8898

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Williiam Charles Akey

Language

en

Proquest ID

AAI8920106

File Format

application/pdf

File Size

90 pages

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