Minimizing abrasion losses from film-coated corn seeds

Film-coating is a widely used technology to apply plant protection agents, beneficial microorganisms, and other substances to seeds. During handling and planting operations, fragments of the seed coat can become detached by mechanical abrasion and are released into the environment. Modest reductions in abrasion losses have been achieved by selecting polymers and formulations with improved adherence to seed surfaces. The objective of this study was to investigate a novel approach for reducing abrasion risk with film-coated corn (Zea mays L.) seeds and to evaluate an improved image-based protocol for rapid and effective evaluation of seed abrasion. This study demonstrated that the risk of abrasion losses from film-coated corn seeds was minimized by removing the outer wax layer of the seed pericarp prior to applying coat formulations. Removal of the outer wax layer did not affect seed germination or seedling growth, but it did improve the adhesion strength of the coat to the seed surface and effectively reduced abrasion losses. Coating surface of dewaxed seeds with three different treatment formulations, viz., a commercial seed-coating polymer, a starch-based bioplastic and a soy protein isolate-based preparation, reduced fragment release by 97.6%, 94.8%, and 98.9%, respectively, with respect to non-surface dewaxed seeds. Seed coatings placed in soil for six days deteriorated 2.5% and 72.1% for commercial and bioplastic formulations, respectively, whereas the soy protein isolate coating formulation deteriorated almost completely under the same conditions. Thus, removing the outer wax layer before film-coating seeds and using novel seed coat formulations improved environmental profile of coated seeds.