To ensure uniform maize emergence, the soil at the seeding depth must warm up to 10–12 °C. At temperatures below 10 °C, the germination period extends to 4–6 weeks, which creates a risk of seed rot and 'temperature paralysis' due to metabolic disruption. The exception is cold-tolerant flint maize hybrids, which are capable of germinating at 7–8 °C.
The selection of the sowing date is critically dependent on the balance of moisture and heat. Early sowing allows for the maximum utilization of stored spring moisture, which is necessary for seed imbibition; however, excessive waterlogging in cold soil promotes the development of fungal diseases. Dent hybrids are more sensitive to adverse sowing conditions than flint hybrids, which have a denser seed coat.
Delaying sowing relative to the optimal period leads to a significant decrease in yield due to a shortened growing season. This complicates the achievement of physiological maturity of the ears and increases grain moisture at harvest; therefore, the primary agronomic goal is to complete sowing operations within the shortest possible timeframe once the temperature optimum is reached.
General information about the subject — on the page
Sowing date.