A bioassay with excised potato shoot-tips for assessing the effect of growth-inhibiting volatile compounds in the potato

Summary A bioassay technique is described for assessing growth-regulatory activities of volatile compounds in the potato. Excised potato shoot-tips (3 mm) were cultured aseptically in an aqueous medium in the dark at 25°C. After 7–12 days in culture, growth rates were measured by the increase in length of the treated shoot-tips. The addition of low concentrations (1 μmol/l) of gibberellic acid (GA₃) and kinetin to the culture medium enhanced shoot growth. Known sprout suppressants inhibited growth of shoots in the bioassay. Of those tested 1,4-dimethylnaphthalene was found to be the most potent. The effectiveness of these known suppressants of sprout growth of whole potato tubers in inhibiting growth in the bioassay is presented as evidence of the validity of using this bioassay to detect unknown growth inhibitory volatile compounds evolved by stored potatoes.