INFLUENCE OF STORAGE TEMPERATURE, TUBER SIZE AND NITROGEN NUTRITION ON THE CONTENT OF VITAMIN C IN POTATO

In 2002 some experiments were carried out on potato of the cv. 'Desiree' with the aim to evaluate the influence of storage temperature (5°C, 24°C), nitrogen nutrition (0, 140, 300, 600 kg/ha) and tuber size on the L-Ascorbic acid content, chemically measured by HPLC analysis and by histological studies by silver nitrate staining technique to locate its presence. The evolution of the content of the organic acid in the buds located on the rose end and on the lateral eyes of the tubers was effected during the storage period. The results underlined that, during the storage period, the L-Ascorbic acid content of potatoes decreased, during the first storage phases in the tubers stored at 24°C. Nitrogen fertilisation caused the reduction in the content in L-ascorbic acid, with 20% of concentration in the tubers treated, compared with non fertilised control. Little was the influence of the tuber size on the L-AsA content. The study on the evolution of the L-ascorbic acid content in the buds of the eyes underlined the increase of the content in L-ascorbic acid 33 days after harvesting, suggesting possible involvements of this organic acid during the dormancy period of the tuber.