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Agronomy Journal Abstract -

Soybean Growth Responses and Intraspecific Competition from Simulated Seedcorn Maggot Injury


This article in AJ

  1. Vol. 82 No. 6, p. 1057-1063
    Received: June 5, 1989

    * Corresponding author(s):
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  1. Leon G. Higley  and
  2. Larry P. Pedigo
  1. D ep. of Entomol., Univ. of Nebraska, Lincoln, NE 68583-0816
    D ep. of Entomol., Iowa State Univ., Ames, IA 5001



The consequences of early-season insect injury on subsequent plant development often are obscure. Further, such injury may produce intraspecific competition between injured and uninjured plants. We examined these issues by studying the impact of simulated seedcorn maggot (SCM) [Delia platura (Meigen) (Diptera: Anthomyiidae)], injury to soybean [Glycine max (L.) Merr.], in field studies from 1983 to 1986 in Iowa. Simulated SCM injury includes plant density (simulating stand reductions) and normal to Y-plant ratios (simulating various proportions of plumule injury). The Y-plants are plants that have had the plumule destroyed and subsequently develop two main stems. Our objectives were to describe how simulated SCM injury affected: (i) development of soybean stands, individual normal plants, and individual Y-plants, and (ii) intraspecific competition between normal and Y-plants. Higher crop growth rates (CGRs) and leaf area indices (LAIs) were associated with higher plant densities. Generally, plumule-injured plants were more affected by plant density than uninjured plants. Examinations of competition between uninjured and plumule-injured plants indicated that uninjured plants were competitively superior to plumule-injured plants. Competitive interactions were influenced by plant density, Phenological delay associated with plumule injury contributed to height differences between uninjured and injured plants, which led to substantial differences in leaf area, number of nodes, and other developmental parameters between injured and uninjured plants. Consequently, unequal competitive ability between uninjured and injured plants was identified as a major consequence of plumule injury.

Contribution from the Dep. of Entomol., Journal Paper no. J-13545 of the Iowa Agric. and Home Econ. Exp. Stn., Projects 2580 and 2633.

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