Ascorbic Acid and Total Phenolics Content in Early Potatoes as Affected by Growing Season, Genotype and Harvest Time

The influence of genotype and harvest time was investigated on tuber ascorbic acid (AA) and total phenolics contents of early potatoes in two growing seasons (winter-spring and summer-autumn crops) in the Mediterranean area. Genotypes included 4 advanced breeding clones suitable for early potato production and 3 commercial cultivars: 'Marabel', 'Nicola' and 'Spunta'. The harvest time was made at 102 and 120 days after planting in the winter-spring season and at 77 and 100 days after planting in the summer-autumn season. AA content was very similar in the two growing seasons, whereas in the summer-autumn season much higher levels of total phenolics were found in all studied genotypes. Genotype appeared to play an important role in affecting ascorbic acid and phenolics content with breeding clone M4 showing a higher tendency than other genotypes to accumulate the two compounds in tubers. After a delay of harvest time, phenolics content of tubers decreased in both growing seasons, whereas ascorbic acid content increased in winter-spring and decreased in summer-autumn. Our results indicate that by choosing growing season, genotype and harvest time, it is possible to increase the actual daily intake of ascorbic acid and phenolics in our diet.