The use of growth retardants to improve microtuber formation by potato (Solanum tuberosum)

The growth retardant chlormequat stimulated microtuber formation by a recalcitrant cultivar of potato (Solanum tuberosum), but reduced microtuber fresh weight in a cultivar that tuberised readily in its absence. Inhibition of microtuber growth by high concentrations of chlormequat was confirmed using a different in vitro system where all cultivars tuberised in the absence of growth retardants.Alternative growth retardants were tested. Daminozide also had a detrimental effect on microtuber fresh weight, but ancymidol and paclobutrazol did not inhibit microtuber growth at the concentrations required for stimulation of tuberisation by recalcitrant cultivars. In addition, 10^-5 M ancymidol and paclobutrazol inhibited premature sprouting of microtubers in vitro.Abbreviations BA benzyladenine - DMSO dimethyl sulphoxide - FW fresh weight - PAR photosynthetically active radiation - SE standard error