Efficacy of glufosinate and weed control in transformed corn and soybean
Steckel, Gregory Joseph
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https://hdl.handle.net/2142/20511
Description
Title
Efficacy of glufosinate and weed control in transformed corn and soybean
Author(s)
Steckel, Gregory Joseph
Issue Date
1996
Doctoral Committee Chair(s)
Wax, Loyd M.
Department of Study
Crop Sciences
Discipline
Crop Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Agronomy
Chemistry, Agricultural
Language
eng
Abstract
Glufosinate is a postemergence herbicide that inhibits the glutamine synthetase enzyme in plants, causing an accumulation of ammonia, inhibition of photosynthesis, and ultimately plant death. The use of this herbicide has been limited to no-tillage prior to planting or in noncrop areas. Recent developments in gene transfer technology have produced crop plants that are tolerant to postemergence applications of glufosinate. Information on glufosinate efficacy on annual weed species is limited. The objectives of this research focused on defining use rates and application timings of glufosinate for effective weed control, evaluating weed control programs in tolerant corn and soybean, and characterizing foliar absorption and translocation of glufosinate as possible physiological mechanisms for plant tolerance.
Field experiments demonstrated that weed species sensitivity to glufosinate was influenced by rate and application timing. Giant foxtail was the most sensitive species evaluated and was controlled effectively with the 280 g/ha rate of glufosinate applied at the 10-cm application timing. Common cocklebur and Pennsylvania smartweed required a rate of 420 g/ha of glufosinate to be adequately controlled. Common lambsquarters was the most tolerant species evaluated and was not consistently controlled even with the 560 g/ha rate of glufosinate. The 10-cm weed height application timing generally gave the best control on all weed species compared to glufosinate applied at either the 5 or 15-cm timing.
Glufosinate tolerant corn displayed excellent safety to all rates of glufosinate that were applied. Glufosinate applications of 400, 600, and 800 g/ha caused some minimal soybean injury but did not result in grain yield reduction. The most consistent season long weed control in either the corn or soybean experiment was provided by glufosinate applied sequentially, followed by a cultivation, or tank-mixed with a residual herbicide compared to a single application of glufosinate postemergence.
Increased absorption and translocation of glufosinate was correlated with efficacy for the four weed species at the whole plant level. Cumulative absorption of glufosinate increased with time and had the following order 24 HAT giant foxtail $>$ barnyardgrass $>$ velvetleaf $>$ common lambsquarters agreeing with the growth reduction data. Translocation of glufosinate from the treated leaf was found to be greater in the two grass species compared to the two broadleaf species and was also related to the degree of whole plant activity that was achieved.
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