Some anatomical and physiological potato tuber characteristics and their relationship to hollow heart

Abstract

The inception site of hollow heart (HH) and possible relationships between HH and physiological or anatomical characteristics of tubers were investigated. Scanning electron micrographs revealed cells at the site of HH inception were physically rather than enzymatically degraded. Transmission electron micrographs of tuber pith cells from non hollow (NH) tubers showed cell wall and cytoplasm width varied among cultivars but were not related to HH resistance. Water potential of NH tuber tissues at the pith, bud, center and stem end of 3 cultivars and one selection varying in resistance to HH was determined. Although the water potential gradually became less negative as tubers advanced in maturity, no differences were found in water potential between pith cells in various parts of tubers or among cultivars. Tuber pith cells increased in size concomitant with tuber growth. In all tubers pith cells were largest in the center and stem end and smallest in the bud end, but differences in mean pith cell size among cultivars were not related to HH susceptibility. However, within a cultivar the bud, center, and stem end pith cells of HH tubers were all smaller than the corresponding pith cells from similarly sized NH tubers.