Ezequiel Lopes do Carmo

Chemical composition of potato tubers: the effect of cultivars and growth conditions

AbstractThe aim of the study involved evaluating the chemical composition of tubers of five potato cultivars that were grown under the same cultural practices in soils with low, medium, and high availability of phosphorus. The experimental designs corresponded to a randomized block with four replicates. Tuber samples were analyzed in terms of moisture, ash, protein, lipid, total sugar, fiber, starch, and phosphorus contents. The results suggested that increased availability of phosphorus in soil allowed the production of tubers with higher dry matter content, lower total sugar content, and a higher percentage of starch and protein. Hence, the aforementioned parameters constitute important factors corresponding to the nutritional and industrial quality of potatoes. Increased phosphorus availability in soil can promote significant changes in the composition of potato tubers, and thereby in potential uses of tubers.

FRUIT COMPOSITION OF 'NIÁGARA ROSADA' AND 'FOLHA-DE-FIGO' GRAPEVINES UNDER DIFFERENT TRAINING SYSTEMS

ABSTRACT - This work aimed on evaluating the influence of training systems in berries composition of ‘Niagara Rosada’ and ‘Folha-de-Figo’ grapevines grown in Caldas, MG. Yield per plant; diameter, weight, temperature and potassium content of the berries; pH, soluble solids, reducing sugars, total acidity and organic acids of the must; anthocyanins and phenolic compounds of the skins and phenolic compounds of the seeds were evaluated in grapevines training in vertical shoot position, lyre trellis, pergola Veronese or simple string in 2006 and 2007 seasons. ‘Niagara Rosada’ and ‘Folha-de-Figo’ grapevines training in pergola Veronese and lyre trellis, respectively, showed higher yield than the other training systems under study. Ber-ries grown under the four different training systems were cooler than ambient temperature, resulting from partial or deep shade clusters. Berries harvested from pergola Veronese trellis system showed lower soluble solids and reducing sugars levels in both cultivars. These preliminary data show that training systems exerted little influence on berries composition.Index terms: Vitis labrusca, phenolic compounds, sugars, anthocyanins, management, quality.