Recent Advances in Seed Preservation Techniques

Abstract

Although seed longevity and storage have been of interest to humankinsd since the beginning of agriculture, the systematic collection and long-term preservation of seed germplasm is only a relatively recent practice of the 20th century. Seed longevity claims of thousands of years have not been verified by the scientific community However, seed viabilities in the range of a few hundred years have been well documented. Even some vegetable seeds, which have been thought to survive only a few decades, have recently been shown to germinate after more than 50 years of storage. The search for physiological, biochemical, and/or biophysical mechanisms of seed deterioration has begun to shed new light on how seeds lose their vigor and germinability. Some studies of particular interest have focused on the integrity of cell and organelle membranes, the fragility of DNA and chromosomes, and more recently the role of water in controling longevity at various temperatures. In the case of membrane integrity, we have learned that membranes undergo phase transitions between the gel and liquid crystalline configurations, depending upon the moisture content; and, that this can be controlled by temperature. The genetic integrity of a seed or a population of seeds can be altered considerably during seed aging and deterioration, thus resulting in loss of variability or genetic shifts in populations. A better understanding of the interrelationships between seed moisture content and storage temperature has just recently shed new light on the potential longevity of orthodox seeds. This understanding of deterioration may lead to the rescue of aged seeds and the retrieval of valuable genes once thoughtlost. In addition to the factors of moisture content and temperature, the seed developmental stage, is now known to be vitally important in the preservationof recalcitrant seeds. In this day, modern genebanks cannot limit themselves to orthodox seed preservation alone.