Disclosed are methods of enhancing growth of corn plants, comprising treating corn seed or the corn plant that germinates from the seed with an effective amount of at least one chitooligosaccharide, wherein upon harvesting the corn plant exhibits at least one of increased plant yield measured in terms of bushels/acre, increased root number, increased root length, increased root mass, increased root volume and increased leaf area, compared to untreated corn plants or corn plants harvested from untreated corn seed.