Effects of Maturity and Determinacy in Soybean on Host-Parasite Relationships of Heterodera glycines
AbstractThe effects of soybean maturity and determinacy on the host-parasite relationships of Heterodera glycines were investigated in a field microplot study over 2 years. Determinate and indeterminate isolines of the maturity group (MG) III cultivar Williams 82 and the MG V cultivar Essex were grown in microplots artificially infested with a race 3 isolate of H. glycines at three initial population (Pi) densities (0, 300, and 3,000 eggs/100 cm³ soil). Soybean seed yields, nematode final population (Pf) densities and reproductive index (Pf/Pi), and root colonization by Macrophomina phaseolina, the causal agent of charcoal rot, were monitored in each year. Seed yields were reduced (P = 0.05) in the presence of H. glycines in both years, but losses were greater in 1996 in the absence of drought stress. Yield loss was lower (P = 0.06) for the determinate isoline of Essex than for the other cultivar-isoline treatments across years. Nematode reproduction was density-dependent in the more conducive environment of 1996 but was unaffected by soybean maturity or determinacy traits. Root colonization by M. phaseolina increased (P = 0.05) in the presence of high H. glycines densities on determinate, but not indeterminate, isolines. Differences in H. glycines-induced yield loss among cultivar-isoline treatments were not related to nematode reproduction, M. phaseolina colonization, or environmental stresses. These results indicate that the effects of soybean maturity and determinacy on H. glycines-soybean interactions are not independent and that their combined effects must be considered in geographic regions where both traits vary.
Copyright and Permissions
All material published by the Society of Nematologists (SON), except for papers prepared by United States and Canadian government employees, is copyrighted and protected under the U.S. copyright law. Under the Copyright Act of 1976, the term of copyright for materials registered by an organization is 75 years from the date first published. Before publishing any manuscript, SON requires that authors transfer full and complete ownership of any copyright to SON by signing a JON Page Charge/Copyright Form (.pdf). SON then registers the copyright. Subsequent use of published materials requires written permission from the SON and may be obtained by contacting the current Editor-in-Chief and state where and how the material will be used.
The author warrants that the article is an original work not published elsewhere in whole or in part, except in abstract form, and that the author has full power to make this grant. If portions of the article have been published previously, then the author warrants that permission has been obtained from the copyright holder and the author will submit a copy of the permission release with this copyright transfer form.
SON shall claim no proprietary right other than copyright. Authors and coauthors retain the right to revise, adapt, modify, or otherwise use all or part of the article in future works of the author(s), such as press releases, lectures, and reviews, provided that all such use is for the personal noncommercial benefit of the author(s). All patent rights are retained by the author(s).