Relationship Between Laboratory Cold‐Test Methods and Field Emergence in Maize Inbreds1

Abstract

AbstractReliable estimates of field emergence under adverse planting conditions are required for maximum crop management. The “cold‐test” is widely used as such a parameter. Various versions of the laboratory cold‐test for corn (Zea mays L.) were studied on 15 inbred lines. Substrates ranged from sterile Kimpak to sand‐soil mixtures to a test utilizing pure soil. All procedures incorporated a 10 C 7 day stress period followed by a grow‐out period at approximately 25 C. Variability between test results on the same sample was as much as 60%. The lowest coefficient of variability was achieved with a method incorporating a cellulose substrate covered with a small amount of soil. The test utilizing the sterile substrate was found to have laboratory performance characteristics similar to the soil tests. It appears that for the inbreds studied, much of the cold‐test response is due to the temperature stress and little to the soil.The ability of any of the tests to predict field emergence was quite variable. The lowest correlation and predictability was recorded with the method suggested by the AOSA Vigor Committee, while the sterile substrate test exhibited intermediate correlation performance compared to the other methods involving soil or soil mixes.The cold‐test is not a consistently reliable predictor of early field emergence. The variability inherent in the test makes comparison between laboratories difficult.