Yield and nutritional composition of sweet potatoes storage roots in response to cultivar, growing season and phosphate fertilization.

Sweet potato is an important food security crop, and the world market for this root is on the rise. Based on the physiological changes in plants in response to climatic conditions and fertilization, this study evaluated the effects of the growing season (rainy and dry season) and P2O5 doses (0, 50, 100, 200 and 400 kg ha-1) on total yield, marketable classes yields, as well as chemical composition of storage roots of two sweet potato cultivars. The storage roots yield was greater in the rainy season. The optimum agronomic and economic doses were 128 and 95 kg ha-1 P2O5 for the cultivar Canadense. Cultivar Uruguaiana did not respond to phosphate fertilization, but its storage roots had higher contents of dry matter, lipids, fibers, total and reducing sugars, and starch. Sweet potato cultivation in the rainy season with doses up to 100 kg ha-1 P2O5 increase root yield in marketable size classes in higher economic value and with higher carbohydrate contents. The results can help producers schedule the planting and harvesting of sweet potatoes throughout the year and contribute to the seasonal management of phosphate fertilizer application. [ABSTRACT FROM AUTHOR]