Influence of sowing date on emergence characteristics of maize seed coated with a temperature-activated polymer

Cold, wet soils, coupled with a short growing season, create a narrow window of optimum time for planting corn (Zea mays L.) in the northern Corn Belt. Temperature-activated polymer (TAP) coatings designed to inhibit planted seed from imbibing water until adequate soil temperatures are reached to promote germination and emergence may offer potential for planting corn exceptionally early. A study from 2000 to 2002 was conducted in west central Minnesota on a Barnes soil (Calcic Hapludoll) to determine the potential for earlier-than-average planting of TAP-coated corn seed. The objective was to compare emergence characteristics of coated and uncoated hybrid corn planted early and at a near-average planting date. Seed planted 29 Mar. 2000 and 24 Apr. 2002 remained in the soil for as long as 26 to 32 d before emerging. In these instances, stands from TAP-coated seed, which ranged from 60 to 90% of seed planted, were generally greater than those of uncoated seed, which ranged from 49 to 68%. Stand establishment and time required to obtain 50% and from 10 to 90% emergence for most early planted coating X hybrid seed combinations were similar to uncoated seed planted at near-average planting dates of 1, 14, and 16 May in 2000, 2001, and 2002, respectively. When both coated and uncoated seed were sown at an average planting date, stand establishment was similar, but emergence for coated seed was generally delayed. Results of this study indicate that TAP coatings protected seeds from injury caused by extended exposure to cold soils, and therefore, might be a useful management tool for early corn planting.