Tetrazolium staining predicts germination of commercial seed lots of European native species differing in seed quality

The germination of 113 commercially available seed lots taken from eight European native species was evaluated and the requirement for dormancy-breaking treatment (250 mg l(-1) gibberellic acid, GA(3); cold stratification) investigated. Laboratory germination, assessed as radicle emergence, of seed lots of single species from different suppliers was highly variable, ranging from 0 to 99%. This highlighted the problem of seed quality in the European native seed market. GA(3) gave small increases in germination, indicative of little dormancy, in six species (Centaurea nigra, Cyanus segetum, Knautia arvensis, Prunella vulgaris, Silene vulgaris and Valeriana officinalis) and the effectiveness of dormancy-breaking treatments did not differ between suppliers (i.e. seed origin). In Papaver rhoeas, GA(3) increased germination of some lots indicating intra-specific variation in dormancy. Only a cold stratification treatment significantly enhanced germination in Rhinanthus minor. A tetrazolium (TZ) testing protocol was developed for the eight species which predicted germination of each species in only two days. Furthermore there was a predictive relationship (R-2 = 0.95) between TZ staining and germination across all species. We therefore propose that TZ staining could be used as a rapid routine method for assessing the germination of many native species, even when dormancy is present.