Studies on the Potato Sprout Suppressant/Fungicide Tecnazene

Leonard, Martin John (1988) Studies on the Potato Sprout Suppressant/Fungicide Tecnazene. PhD thesis, University of Glasgow.

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This thesis describes work relating to the use of potato sprout suppressant chemicals - compounds which are used to control the sprouting of potatoes during extended storage. In particular, several implications of the use, in commercial situations, of one of these compounds, tecnazene, were assessed. This included a study on the effects on subsequent field growth of a range of tecnazene residues in seed potatoes at planting - this chemical having previously been cited as a cause of delayed emergence and reduced yield. A storage experiment and field trial are described from which it was concluded that a specific effect on emergence and yield cannot be attributed to a given residue at planting, although this can be a useful guide in broader terms. It was considered that a residue at planting of less than 1-1.5 mg/kg on a whole tuber basis would have little effect on emergence and yield. It was also noted that tecnazene treatment resulted in an increased number of stems from each tuber, and in turn to a higher proportion of smaller tubers. This effect was noted for even the lowest application rate indicating that tecnazene treatment could perhaps be used to manipulate tuber size distribution while having little or no effect on emergence and total yield. The method of residue analysis employed in the above work is described in a separate section, along with an assessment of tecnazene toxicology. Two other commercial problems linked to the use of sprout suppressants were investigated, both of which are related to the use of tecnazene in large scale commercial potato stores: The effect of vapour phase application of tecnazene on the healing of tuber wounds is discussed, based on results obtained using a rapid method for assessment of the degree of suberisation and periderm development. Tecnazene treatment appeared to have no detrimental effect on wound healing in contrast to the other major sprout suppressant chemical, chlorpropham, which clearly inhibited the process. This is an important point as incomplete healing of tuber wounds results in water loss and facilitates infection by fungal or bacterial pathogens. The effect of tecnazene, either alone or in combination with chlorpropham, on the incidence of internal sprouting in treated tubers was also studied. This phenomenon occurs when sprouts grow into a tuber rather than out and away from tuber, and renders such tubers useless for processing into crisps. The results indicated that while internal sprouting can occur in the absence of tecnazene, the pattern of sprouting induced by tecnazene treatment would appear to increase the incidence of this disorder. The remaining section of work in this thesis was based on a subject of less practical significance, but of much interest - the mode of action of tecnazene. It was considered that tecnazene might act by inhibiting gibberellin biosynthesis or action and for this reason bean seedling bioassays were conducted in which very dilute aqueous solutions of tecnazene were fed to the plants. This did result in some growth inhibition when compared to controls although it was not nearly as marked as that effected by a known gibberellin biosynthesis inhibitor which was included in these assays, a fact which could possibly be partly explained by the very limited aqueous solubility of tecnazene. Any growth inhibition induced by tecnazene could be overcome by application of exogenous GA3, although, again partly for reaons of solubility, this need not necessarily implicate gibberellin biosynthesis inhibition or site blocking. Further work, probably at the cell constituent level, is required.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Organic chemistry, Agriculture
Date of Award: 1988
Depositing User: Enlighten Team
Unique ID: glathesis:1988-77942
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 30 Jan 2020 15:47
Last Modified: 30 Jan 2020 15:47

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