| Potato minitubers are small pathogen and disease-free seed tubers that are field planted to produce basic seed potatoes. Minitubers have a longer dormancy period than regular tubers. Predictable and consistent dormancy release of potato minitubers is necessary to ensure uniform sprouting and vigorous plant development. Circumstances often require that minitubers be planted soon after they have been harvested from greenhouse benches, creating insufficient storage to satisfy dormancy without additional treatment. There have been few non-hazardous, reliable methods to stimulate early release of potato minituber dormancy in a predictable manner, especially for long dormancy cultivars. Plant growth regulators are important in the regulation and termination of potato minituber bud dormancy. Gibberellins and cytokinins are known to release potato tuber bud dormancy while abscisic acid (ABA) is likely the principal dormancy-inducing plant hormone. This research was based on the primary hypothesis that bud dormancy in potato minitubers can be released by application of plant growth regulators, chemicals and exposure to a magnetic field. The objectives were to explore the effects of different temperature regimes, plant growth regulators, electromagnetic field and chemicals on minituber bud dormancy and to develop a more effective minituber dormancy release protocol.; Alpha-galactosidase is a key catabolic enzyme of the raffinose family oligosaccharides (RFO), involved in seed germination of many species. Its primary function is to break the terminal-linked moiety from galactose containing oligosaccharides. Reducing sugars (fructose and glucose) are known to increase during low temperature storage, presumably as products of enzymatic hydrolysis of complex storage carbohydrates. Phenolic compounds are relatively stable secondary plant metabolites, thought by some to play a role in defense against predators and diseases, and in some species are reported to change as plants pass from a dormant to non-dormant state. We hypothesized that alpha-galactosidase, soluble sugars and total phenolics are related to potato minituber dormancy and dormancy release. The objectives were to explore the relationship of these metabolites to potato minituber bud dormancy and emergence from dormancy.; Abscisic acid (ABA), N6-benzyladenine (BA), Florel (ethrel), ProGibb, kinetin, Pro-BA (ProGibb and BA); Pro-Florel (ProGibb and Florel), BA-Florel (BA and Florel) plant growth regulators, catechin, magnetic field, temperature regimes, minituber sizes, 2,2'-azobis-(2-amidinopropane) hydrochloride (AAPH), and 2,2'-azino-bis(3-ethylbenzothiazolamine-6-sulfonic acid) (ABTS+) (free radical producers) were used as dormancy release agents in this research. (Abstract shortened by UMI.)... |
