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When bisected or deeply cut by knife, yam tubers (Dioscorea rotundata Poir.) undergo a process of wound repair which comprises: (a) an immediate migration of starch to the cut surface (within 5-10 h of injury); (b) after 2-3 days, the formation of a suberized layer beneath the cut surface; (c) after approx. 5 days, the production of periderm (cork). Concurrent with these structural changes are a rapid increase in the rate of respiration, a hydrolysis of starch to sugar and an increase in invertase activity. Metabolic activity remains high until healing is complete. When tubers are wounded by surface abrasion or severe bruising these wound-healing processes do not occur. Weight loss and respiratory activity of bruised tubers remain high until decay. Abrasions or superficial cuts are not sealed off by a layer of periderm, and in consequence a prolonged loss of moisture content and an increased susceptibility to pathogen attack result.
The New Phytologist © 1976 New Phytologist Trust