Microtuberization and dormancy breaking in potato (Solanum tuberosum L.)

This thesis describes experiments designed to improve microtuberization efficiency, and to evaluate a range of dormancy-breaking agents for microtubers and minitubers. Provision of continuous darkness, agitation to cultures, mechanical resistance to stolons, or lower levels of medium nitrogen did not improve microtuberization. The 16/8 h d/n cycle at step 1 of microtuberization was significantly better than 12/12 or 8/16 h d/n cycles based on microtuber yield. Cultures exposed to prolonged step 2 or 2 successive harvests, rather than a single harvest at 30--35 d, had significantly improved microtuber yield. In a series of chemical and mechanical treatments applied to microtubers and minitubers, with or without variable periods of cold storage, 500 mg l -1 GA3 was the most efficient in breaking-dormancy and inducing precocious sprouting. GA3 was the only agent that was able to break dormancy of minitubers that had not been cold stored. After 2 weeks of cold storage, minitubers treated with GA3 also broke dormancy, while Signal was less effective in promoting sprouting. (Abstract shortened by UMI.