Sweet potato constitutes a source of energy and nutrient which is very important economically, especially, for the poorest people in the world, supplies calories, vitamins and minerals in the diet. The determination of the harvest age has great influence on vegetative production, quality, productivity and root biomass. The planting season is determined by climatic elements, which have influence on the growth, development and crop productivity. The objective of this paper was to evaluate the agronomic performance of sweet potato cultivars, as a function of the age of harvest in two growing seasons. Two experiments were conducted, the first in the rainy season and the second in the dry season in semiarid Brazil. In both experiments, the experimental design was a randomized block with split plots with four replications, being the plot formed by three cultivars (ESAM 1, Paraná and Mãe de Família), and the subplot by 5 harvest times (90, 105, 120, 135 and 150 days after planting). The length and diameter of commercial roots, dry mass of roots and shoots, and fitomass production were determined. The diameter, total dry mass of roots, commercial and total productivities of roots showed increasing responses with increasing harvest age in both crop growing seasons. The Paraná cultivar showed the best productive performance among cultivars. The harvest age of 150 days after planting was more productive. The best time of cultivation was in the dry season. Considering the importance of sweet potatoes, further studies are recommended in order to solve some problems related to adaptability and cultural reproduction in other regions to elucidate the effects of harvesting ages and growing seasons at longer intervals.
Key words: Ipomoea batatas, productivity, roots, tuberous.