In vitro microtuberization of potato (Solanum tuberosum L.): effect of plant bioregulators

Effect of plant biodegradators and gelled, liquid and mist media on in vitro stimulation and development of microtubers were studied using "Desiree", "Russet Burbank" and "Spunta" potato cultivars. While apices removal enhanced, "chloromequat and benzyladenine" overcame the inhibitory effect of apex on microtuberization. Exogenous gibberellic acid inhibited microtuberization. Results of the time course experiment revealed that microtuberization and microtuberization potential varied with cultivar and plant bioregulator. In general, average stimulating power, number of microtubers and average microtuber weight were superior when ancymidol was applied (5 mg 1-1) to all cultivars. Average stimulating power was rapid for ancymidol or benzyladenine (0.5 day). Benzyladenin, however, enhanced average stimulating power alone ("Desiree" and "Spuntta") or in presence of chloromequat or salicylic acid ("Desiree"). No transfer is required for "Russet Burbank" and "Desiree" in all plant bioregulator treatments and in absence of benzyladenine, respectively. Maximum average microtuber weight (111.2 mg) was achieved in "Desiree" with 28 days incubation in chloromequat alone. "Russet Burbank" proved to be recalcitrant with prominent premature sprouting. Benzyladenine at 5.0 mg 1-1 showed a reduction in this phenomenon in all cultivars. Average microtuber weight in "Russet Burbank" was reduced with each increase in uniconazole concentration. In contrast, salicylic acid and daminozide had no effects even at 10 mg 1-1. All cultivars produced microtubers when cultured on liquid media; number of microtubers per shoot was 0.9, 0.8 and 0.2 for "Russet Burbank", "Desiree" and "Spunta", respectively. Microtubers of "Desiree" and "Spunta" produced during a storage period of 26 weeks sprouted shortly upon reculturing. Therefore, it is recommended that nodal cuttings of "Desiree" and "Spunta" be cultured in liquid media in presence of ancymidol and benzyladenin (5 mg 1-1 each)