LIFE SPAN OF SEEDS 



35 



were buried bj'' Duvel in 1902. Thirty-two sets of 107 species of wild and 

 cultivated plants were placed in sterile soil in flower pots covered with 

 porous clay lids and buried outside at three different depths, 8, 22, and 

 42 inches. Records of the tests for 1, 3, 6, 10, 16, and 20 years are now 

 available. The tests for the 30-year period were made in 1933, but unfor- 

 tunately there has been great delay in publication. 



Seeds of a number of sorts of wild plants showed little or no germination 

 after shorter burial periods, but considerable to excellent germination after 

 longer burial periods. This may have resulted either from the use of less 

 favorable germination conditions in the earlier tests, or from the gradual 

 after-ripening of the seeds in the soil. At any rate, the conditions used for 

 the later tests Avere fairly favorable for the germination of seeds of wild 

 plants on the surface of flats of sterilized soil in a greenhouse. This provided 

 light, fluctuating temperatures, and the stimulative effect of the soil. It is 

 regrettable that samples of the seeds were not placed in dry storage under 

 a variety of conditions, including sealed storage in the soil. This would 

 have answered the interesting question of the relative life span of the seeds 

 in several dry storage conditions and in the moist soil. 



After 20 years' burial, some seeds of 51 of the 107 species were still alive. 

 The folloAving gives the families, genera, and the highest germination for 

 each genus of those seeds still alive after 20 years. 



Seeds of cultural plants that were dead after 20 years in the soil (and 

 most of them died even after one year in the soil) were: oats, meadow 

 fescues, barley, rye, wheat, corn, onion, asparagus, hemp, buckwheat, cab- 

 bage, turnip, pea, cowpea, bean, pepper, tomato, watermelon, muskmelon, 

 cucumber, lettuce, sunflower, and pine. Seeds of cultural plants that 

 showed some live seeds after 20 years in the soil were: timothy, Kentucky 



