Life-span of seeds

Abstract

Probably few sections of human knowledge contain a larger percentage of contradictory, incorrect and misleading observations than prevail in the works dealing with this subject, and, although such fables as the supposed germination of mummy wheat have long since been exploded, equally erroneous records are still current in botanical physiology. In addition, there are considerable differences of opinion as to the causes which determine the longevity of seeds in the soil or air. The works of de Candolle, Duvel and Becquerel are the most accurate and comprehensive dealing with the question, and, in addition, Vilmorin has published very useful data in regard to the seeds of culinary vegetables. The subject is still, however, in an incomplete and fragmentary condition. Since Ewart's classical work was written, many new data and much evidence have been accumulated in this field, and definite advances have been made in several phases of the subject, including the nature of the changes involved in the degeneration of seeds with age and the effect of storage conditions on their rate of degeneration. Many new records have appeared on life-span of seeds of wild plants in herbaria and seed cupboards and of seeds of cultivated plants in storage. We also now have available considerable reliable data on the life-span of seeds in soil. On the basis of their life-span under optimum conditions, Ewart divides seeds into three biological classes: (A) microbiotic, whose life-span does not exceed 3 years; (B) mesobiotic, whose life-span ranges from 3 to. 15 years; and (C) macrobiotic, whose life-duration ranges from 15 to more than 100 years. As we shall see later, we do not have final information on the optimum storage conditions of many sorts of seeds. Indeed, it is questionable whether we have it for any kind. Until we possess such information, these terms do not have very definite meaning. As we learn of better and better storage conditions for a given sort of seed, it may jump from the microbiotic to the mesobiotic or even to the macrobiotic class.