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This article in AJ

  1. Vol. 97 No. 3, p. 823-831
     
    Received: Sept 7, 2004
    Published: May, 2005


    * Corresponding author(s): thomison.1@osu.edu
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doi:10.2134/agronj2004.0237

Early-Season Defoliation Effects on TopCross High-Oil Corn Production

  1. T. F. Mangena,
  2. P. R. Thomison *a and
  3. S. D. Strachanb
  1. a Hortic. and Crop Sci. Dep., The Ohio State Univ., Columbus, OH 43210
    b Pioneer Hi-Bred Int., P.O. Box 1004, Johnston, IA 50131

Abstract

High-oil corn (Zea mays L.) produced with the TopCross grain production system is planted as a physical mixture (a TC Blend) containing 91% high-yielding, male-sterile hybrid (grain parent) seed and 9% pollinator seed. Field experiments were conducted at two locations in Ohio in 1999 and 2000 to determine if high-oil corn (HOC) TC Blends are more sensitive to defoliation damage than their normal-oil corn (NOC) hybrid counterparts consisting of 100% male-fertile plants. Corn plants were 100% defoliated at V5 and 50 and 100% defoliated at V13. Defoliation similarly affected grain yield and oil concentration of HOC TC Blends and NOC hybrids. Complete defoliation at V13, averaged across years and hybrids, was the most damaging defoliation treatment, reducing grain yields 29%. Defoliation did not significantly alter grain oil concentration of HOC grain parents (74.5 g kg−1) or NOC (34.5 g kg−1). Defoliation caused similar responses in ear weights and oil concentrations in both components (the pollinator and the grain parent) of the HOC TC Blends. The lack of hybrid × defoliation interactions for ear yield components and various agronomic traits indicates that HOC TC Blends and their respective NOC counterparts responded similarly to early-season defoliation over a range of environmental conditions. Guidelines for assessing early-season leaf injury in conventional corn may be suitable for assessing leaf injury in HOC TC Blends.

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