Yield of sweet potato clones in response to nitrogen doses

Determining the agronomic and economically suitable nitrogen dose for the sweet potato crop is a challenge. The objective of this study was to evaluate the effect of N doses on the biomass production and yield of tuberous roots, and to determine the economic dose for the sweet potato crop. The study was carried out from March to August 2011 in Sao Cristavao, Sergipe State, Brazil. A randomized block design was used, in a 5x3 factorial scheme, testing five rates of N (0, 30, 60, 120 and 240 kg/ha), using urea as N source, and three sweet potato clones (IPB-052, IPB-075 and IPB-149), with three replications. The commercial cultivar Brazlandia Branca (IPB-052) was considered as control. Plants were harvested at 150 days after planting. All clones studied reached values higher than the national average root yield (11.84 t/ha). The aboveground part biomass of the evaluated clones responded linearly to the N doses applied. Rate of 130 kg/ha N provided the highest yields for total tuberous roots considering the evaluated sweet potato clones.