The Longevity of Seeds

Roberts (1961) showed that plotting the results of serial germination tests of subsamples of a seed lot stored under controlled conditions provides a sigmoidal curve that conforms to a negative cumulative normal distribution (Fig. Thus, individual seeds within a lot die at different times and the frequency distribution of deaths is normal. It is not possible, therefore, to obtain a single measure of the longevity of a seed lot. Many authors have, however, used the time taken for germination to fall to 50% (p 50 ) as a measure of longevity, an advantage of this period