|Williams, William - Paul|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/1/2005
Publication Date: 10/23/2005
Citation: Clements, M.J., Williams, W.P. 2005. Corn husk characteristics potentially associated with resistance to aflatoxin contamination of grain: a preliminary study [abstract]. In: Proceedings of the 2005 Multicrop Aflatoxin/Fumonisin Elimination & Fungal Genomics Workshop, October 23-27, 2005, Raleigh, North Carolina. p. 88.
Technical Abstract: Feeding damage from several insect pests on corn ears contributes to conditions that favor severe Aspergillus and Fusarium ear rots and severe mycotoxin accumulation in grain. Husk characteristics that serve as barriers to insect movement often are negatively associated with insect feeding damage to ears, and therefore are thought to serve as mechanisms of resistance to disease development and mycotoxin accumulation in grain. Typically, husk tightness has been quantified subjectively either shortly after silking or after plants have dried down and are ready for harvest. Rationale for timing of husk tightness evaluations is not available in literature. Our objective is to identify a plant growth stage or seasonal period at which differentiation of husk tightness among various corn genotypes is maximized. We examined four methods of evaluating husk tightness over six sampling periods in replicated trials at Mississippi State University in 2005. Force required to remove husk leaves from the ear was measured mechanically (gauged pull) and subjectively (subjective pull). Force required push a 3-mm dia. steel rod longitudinally along the ear between husk leaves and kernels was measured mechanically from the tip to the shank end of the ear (adhesion from the tip) and from the shank to the tip end of the ear (adhesion from the shank). Greatest differentiation of husk tightness among genotypes was observed between 28 to 35 days post mid-silk for the four methods evaluated. Gauged pull at 28 days post mid-silk provided greatest range of data, and good resolution to differentiate the four genotypes tested; however, all four methods warrant further examination as potential methods of quantifying husk tightness. This study will be repeated in 2006 along with, potentially, an evaluation of husk tightness among F2:3 families associated with resistance or susceptibility to aflatoxin contamination in grain in another study. Information on timing of husk tightness evaluations will optimize studies aimed at differentiating genotypes with tight or loose husks and the identification of quantitative trait loci associated with husk tightness.