Tillage, hybrid and thermal factors in corn establishment in cool soils

Abstract

Low seedbed temperatures at planting reduce corn ( Zea mays L.) germination, rate of emergence and final stand establishment at many corn producing locations in Canada. Adoption of conservation tillage at these locations and the accumulation of surface residue results in lower seedbed temperatures in the spring and further increases the need for corn hybrids with superior cold tolerance during germination and early growth. In a 3-year study at a continental location (Ottawa, Ontario (45°22′N, 75°43′W)), rate of emergence and final stand establishment were determined each year for a single commercial hybrid planted under four tillage management treatments (conventional mouldboard, chisel, ridge and no-till). In a separate 2-year study under conventional tillage, with three planting dates, carried out at Ottawa and at a maritime (Charlottetown, Prince Edward Island (46°14′N, 63°9′W)) location, the range in emergence rate and stand establishment were determined for 11 commercial hybrids bred for northern production areas. Seedbed temperatures were monitored in both experiments. Rate of emergence and final stand establishment of all hybrids were reduced by lower seedbed temperatures, and there were differences between the response of different hybrids to seedbed temperature. Conservation tillage, in particular, no-tillage, resulted in more variable emergence rates and reduced stand establishment compared with those of conventional tillage. Refinement of the corn temperature response function for the emergence period resulted in an improved thermal index for corn development from planting to emergence.