HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (16) Citing Articles via Google Scholar Google Scholar Articles by King, C.A. Articles by Vories, E. D. Search for Related Content PubMed Articles by King, C.A. Articles by Vories, E. D. Agricola Articles by King, C.A. Articles by Vories, E. D. Related Collections Weed Management Soybean Agricultural Pesticides Crop Growth and Development Crop Physiology & Metabolism

SOYBEAN

Plant Growth and Nitrogenase Activity of Glyphosate-Tolerant Soybean in Response to Foliar Glyphosate Applications

^a Dep. of Crop, Soil, and Environ. Sci., Univ. of Arkansas, 1366 W. Altheimer Dr., Fayetteville, AR 72704
^b Dep. of Biol. and Agric. Eng., N.E. Res. and Ext. Cent., Univ. of Arkansas, Keiser, AR

Corresponding author (lpurcell{at}uark.edu)

Glyphosate [N-(phosphonomethyl)glycine] inhibits 5-enolpyruvylshikimate-3-phosphate synthase, EC 2.5.1.19 (EPSPS), thereby blocking aromatic amino acid synthesis. While glyphosate-tolerant (GT) soybean [Glycine max (L.) Merr.] contains resistant EPSPS, the N₂-fixing symbiont in soybean root nodules, Bradyrhizobium japonicum, does not contain a resistant enzyme, and glyphosate spray to GT soybean may interfere with the symbiotic relationship. Glyphosate-tolerant soybean was treated with glyphosate at several different stages of development to evaluate N₂ fixation, growth, and yield in a series of greenhouse, growth chamber, and field experiments. Early applications of glyphosate generally delayed N₂ fixation and decreased biomass and N accumulation in the cultivar Terral TV5866RR (TV5866RR) harvested at 19 d after emergence (DAE), but plants had recovered by 40 DAE. The biomass and N content of GT soybean were also decreased by glyphosate in plants that were grown with available soil N. There were differences in sensitivity to glyphosate among GT cultivars, with biomass decreases in response to glyphosate ranging from 0 to 30% at 40 DAE for the most tolerant and sensitive cultivars that were evaluated. In growth chamber studies, N₂ fixation was more sensitive to water deficits in glyphosate-treated plants. In field studies, there was no measured effect of glyphosate on GT soybean at Fayetteville, AR where there was adequate soil water throughout the growing season. However, glyphosate tended to decrease biomass and seed yields under conditions of limited soil water at Keiser, AR.

Abbreviations: ARA, acetylene reduction activity • DAE, days after emergence • DI, deionized • EPSPS, 5-enolpyruvylshikimate-3-phosphate synthase • FTSW, fraction of transpirable soil water • GT, glyphosate tolerant

This article has been cited by other articles:

				A. L. Cerdeira and S. O. Duke The Current Status and Environmental Impacts of Glyphosate-Resistant Crops: A Review J. Environ. Qual., August 9, 2006; 35(5): 1633 - 1658. [Abstract] [Full Text] [PDF]

				P. P. Motavalli, R. J. Kremer, M. Fang, and N. E. Means Impact of Genetically Modified Crops and Their Management on Soil Microbially Mediated Plant Nutrient Transformations J. Environ. Qual., May 1, 2004; 33(3): 816 - 824. [Abstract] [Full Text] [PDF]

				R. M. Zablotowicz and K. N. Reddy Impact of Glyphosate on the Bradyrhizobium japonicum Symbiosis with Glyphosate-Resistant Transgenic Soybean: A Minireview J. Environ. Qual., May 1, 2004; 33(3): 825 - 831. [Abstract] [Full Text] [PDF]

				L. G. Heatherly, S. R. Spurlock, and K. N. Reddy Influence of Early-Season Nitrogen and Weed Management on Irrigated and Nonirrigated Glyphosate-Resistant and Susceptible Soybean Agron. J., March 1, 2003; 95(2): 446 - 453. [Abstract] [Full Text] [PDF]