The influence of the environment on seed and seedling mortality

Summary 1. Some of the differences between various techniques of cold testing corn have been examined. No significant difference was found between the results of cold testing by exposing grains to temperatures between 3° and 20°C after 0 and 2 days pre-treatment at 20°C (Erratic results are reported for the mortality induced by exposure of pre-germinated grains to 0°C).2. Mortality in the cold test increased with time of exposure up to 10 days (the longest period involved in the experiments). Varietal differences between Wisconsin 275 and Virginian White Horsetooth became more pronounced with increased period of exposure.3. There was relatively little change in mortality between the cold tests conducted at 3° and 8°C compared to the large change between 8° and 15°C. It is suggested that the temperature of the test should be standardised within the lower range, where small uncontrolled variations in temperature will have least effect on the tests. Attention is called to the fluctuation in soil temperature which may be caused by variations in atmospheric humidity in a constant temperature room.4. Comparison of cold tests made (a) in jam jars of soil with subsequent sowing of the grains in damp sand at a higher temperature with (b) tests involving grain treated in boxes of soil in which the grains remainin situ through all phases of the test, reveal no differences due to these contrasted procedures.