Seasonal carbohydrate changes in two sweet orange varieties of the Navel group

Sugar and starch levels were determined in leaves, fruits, bark and roots of the ‘Navelate’ variety (low yield) and compared with those of ‘Washington Navel’ (standard yield). Old leaves had the lowest sugar content in May, while young leaves had a decreasing content from spring to summer in both varieties. ‘Navelate’ had lower sugar content in leaves, bark and roots than ‘Washington Navel’. Starch levels in the leaves showed a maximum towards the end of May. In winter, ‘Navelate’ had a higher starch content, mainly in the roots and bark, due to its low yield.