Seed Banks

Abstract

During recent years the occurrence of genetic erosion in the centres of diversity of cultivated plant species, as Professor Hawkes has pointed out in this volume, can be observed in an ever increasing and in part dangerous amount. On the other hand due to the work of plant breeding our crop plants are becoming more and more uniform. In other words, the genetic diversity or heterogeneity is decreasing to such an extent that genetic variability of our crop plants is in great danger. An impressive example (which also illuminates the agricultural significance of this phenomenon) is the fall of the maize yield in the USA in 1970 caused by the attack of Helminthosporium maydis (Southern corn blight). The overall average drop in yield was 15% and losses of up to 50% were recorded in individual areas. The almost exclusive use of the so-called “Texas Cytoplasm” in the hybrids gave rise to a degree of uniformity which made an epidemic of the disease possible.