AbstractThe germination of raspberry seeds was favoured by applying certain combinations of chemical pretreatment before giving up to six weeks of moist-chilling before sowing, by adding 500 p.p.m. gibberellic acid just before sowing, and by providing supplementary light after sowing. The most useful chemical pretreatment was 20 minutes with concentrated sulphuric acid followed by six days with 1.0 per cent calcium hypochlorite containing an excess of calcium hydroxide. For some seed samples such pretreatment eliminated the need for a subsequent period of moist-chilling, but for others a six-week period of moist-chilling was still required. Pretreatment with higher concentrations than 1.0 per cent of calcium hypochlorite, 0.5 per cent of sodium hypochlorite, or 1.0 per cent of thiourea, or pretreatment with the stated concentrations of these chemicals but in each case without the addition of calcium hydroxide, frequently delayed or prevented germination. The results of these studies are in accord with the hypothesis that the germination capacity of raspberry seeds is determined by interactions between growth inhibitors and promoters. Such substances have been detected in blackberry seeds and it is suggested that a similar situation exists in seeds of the raspberry.