Relationships of hollow heart in Irish potatoes to carbohydrate reabsorption and growth rate of tubers

Abstract

Tubers of Irish Cobbler that were hollow grew faster than non-hollow tubers on the same plant. However, tubers of varieties without hollow heart grew just as rapidly as tubers of the variety with hollow heart. Therefore tuber growth rate was related to hollow heart occurring within a variety but could not account for differences between varieties. When plant foliage was pruned the C-14 label from sucrose was translocated from the tuber to the top of the plant. Our studies suggest hollow heart can occur in small tubers under the following conditions: (i) moisture stress in the tubers resulting in conversion of starch to sugar, followed by a rapid influx of water into the tuber resulting in rapid enlargement of the perimedullary zone and a separation in the pith that later develops into hollow heart, and/or (ii), following injury to some cells in the tuber due to reabsorption of minerals and carbohydrates or depletion of food reserves followed by tuber enlargement. It seems probable however that hollow heart that is initiated in large tubers is only associated with excessively rapid tuber enlargement without the involvement of reabsorption or depletion of food reserves.