The Aetiology of Vascular Discoloration in Cassava Roots after Harvesting: Association with Water Loss from Wounds

Abstract

Abstract When root pieces of cassava, Manihot esculenta Crantz (cv. Yellow Heart or cv. Cuba Sweet), with an area of periderm removed or with a transverse cut uncovered, were held at low humidity and at 22°C, vascular discoloration consistently developed within 2 days. Vascular discoloration was prevented when injured pieces were stored at high humidity or when wounds were covered by a semi‐permeable film. When pieces were injured by removal of periderm, at high humidity the respiratory rate was unaltered but at low humidity an increase in respiratory rate occurred after 1 day. When pieces were injured by a transverse cut, at high humidity respiratory rate increased during the first day but decreased thereafter, whereas at low humidity the initial increase was followed by a further increase in respiratory rate after 2 days. It is suggested that vascular discoloration and a respiratory increase may occur in freshly harvested cassava roots as a result of stress produced locally by high rates of water loss at cuts and abrasions.