ABSTRACT
Pre-harvest sprouting is widely recognized as being a significant problem in the production of quality cereal grain in many areas of the world. Consequently it is not surprising that many breeders are trying to improve the tolerance of their varieties either through deliberate selection of more tolerant parents or by selection within breeding populations. In general, the source of tolerance has been selected from within the existing cultivated germplasm for the species in question, unlike the situation in disease resistance breeding where erosion of resistance genes has forced breeders to look at wild species and related genera. In wheat there are a considerable number of recognized species and races, many of which have not been subjected to intense selection or domestication, which represent a potential pool of new and different sources of tolerance to sprouting. MacKey (1976) discussed the property of seed dormancy and noted that wild cereals where all characterized by levels of dormancy which enabled them to survive and adapt to particular environments. MacKey (1976) also discussed the loss, during domestication, of some mechanisms which prevented precocious germination. Whilst some of these are likely to be incompatible with the agronomic and quality requirements of modern cereals, others may well be of considerable use. Gordon (1983) examined a range of wheat varieties and species and noted considerable variation in sprouting tolerance. The aim of the present investigation was to extend this study to include members of all the commonly recognized species and races of wheat (Peterson, 1965), to characterize tolerance in relation to the range already established in the hexaploid bread wheats 149and, in addition, to compare wheat with the alternate winter cereal crops such as barley and triticale which are currently cultivated in Australia.
