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Title: Dormancy and sprout control in root and tuber crops
Author: Cheema, M. U. A.
ISNI:       0000 0004 2714 5330
Awarding Body: University of Greenwich
Current Institution: University of Greenwich
Date of Award: 2010
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Research objectives were to study dormancy/sprout control in potato and sweetpotato, and to identify novel sprout control strategies. Consistent with sprout stimulation by gibberellins (GAs) in potato, 10 mM GA3 enhanced sprout length and number in sweetpotato roots and sprout growth was decreased by 20 ml/L piccolo (GA synthesis inhibitor). Continuous application of 10 ppm ethylene or greater prevented sprouting in sweetpotato roots over 4 weeks storage at 25° C. Sprout growth was also inhibited by 1000 ppm aminoethoxyvinylglycine (AVG) (ethylene synthesis inhibitor) or 625 ppb 1-methylcyclopropene (1-MCP) (ethylene antagonist). Continuous ethylene treatment or single 1-MCP treatment could be a practical sprout control method for sweetpotatoes stored at >15° C. 5 ppm or greater ethylene increased root respiration rates, but this effect was reduced by 1-MCP or AVG. Sugar content in ethylene treated roots +/- 1-MCP or AVG were lower than untreated roots, with lowest levels in roots treated with ethylene alone. Hormonal control of dormancy/sprout growth was studied in excised buds from potato tubers transformed to over-express a bacteria gene encoding 1-deoxy-D-xylulose 5 phosphate synthase (DXS), which exhibit arrested buds, Five weeks post-harvest over-expressing lines, DXS1 and DXS2, showed greater sprout growth compared to wild type when treated with 1 mM GA3 or tZR in 2009, whereas DXS1 showed less sprout growth 4 weeks post-harvest in 2007. There was no difference in DXS1 and DXS2 behaviour 4 months after harvest in 2007. The different behaviour of DXS1 over seasons and with time from harvest underlines how tuber state can change with maturity. No consistent differences were found in chemical profile of peel among potato tubers of accessions with a range of dormancy characteristics. Although 1, 4-Dimethylnaphthalene has been identified as a natural sprout suppressant, it could not be detected in any accession even though measurements were sensitive to below 100 ppb.
Supervisor: Rees, Deborah ; Westby, Andrew Sponsor: Natural Resources Institute
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: SB Plant culture