Fertilisation of three potato cultivars i.e. Herms, Lady Rossetta and Lady Joy
with Calcium chelate and Calcium nitrate decreased Erwinia sp. tuber rots, increased starch content and the cation content in the medulla. Greater effect was observed on Herms tubers compared to Lady Rosetta and Lady Joy. Weight loss due to soft rot incidence was significantly reduced by approximately 50% after 5 weeks of storage nd by one and a half fold after 18 weeks. The reduction in potato soft rot was inversely related to the content of tuber calcium in the field. The tubers obtained from plots Irealed with calcium salts had calcium contents in the medulla of tested cultivars ranging between 21.5 to 6. tpprn (on dry weight basis) with the greatest content in Herms tubers. When tuber calcium was increased, the decayed tubers due to Erwinia soft rot was significantly reduced and tuber starch content was enriched in the tissue. The scanning electron microscopy (SEM) revealed compactness of cell structure and cell wall integrity due to calcium application. Calcium application preferentially enriched the outer cell layers of the treated tubers causing lessening in the intemal diameters of parenchyma cells.