The Iowa Cold Test
The (Iowa) Cold Test gives a reasonable idea of emergence under less than ideal, but not severe, conditions. The Iowa Cold Test has been conducted at Iowa State for more than 40 years.
Corn (primarily, but also soybean, cereals and other species) traditionally is tested at 10°C (50°F) for seven days and then at 25°C (77°F) for seven days., but a quick cold test is available – three days at 10°C and four days at 25°C. The 14 days test can be reduced to seven days cold and 4-5 days warm without significantly differing from the longer test.
The Iowa Cold Test
Test Details
Two replications of 100 seeds are placed on Versapak® that has been moistened and chilled overnight at 10C. The amount of water added will bring the sand/soil used to cover the seeds to 70% of its water holding capacity. The germination cart is returned to 10C for seven days without light. The cart is moved to 25C for seven additional days (4-7 are an option). A quicker option is to for the cold period to be three days and the warm period four days.
Seedlings that emerge through the sand/soil mixture are evaluated according to modified AOSA Rules For Testing Seeds. The modification reflects the need for stronger root and shoot development under stressful conditions. The use of sand & soil are recommended in the AOSA Seed Vigor Testing Handbook.