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This paper reports a preliminary study of four sweet potato varieties, Russia, Napoleão, Roxa and Viçosa, carried cut in 1939-40 at the Central Experiment Station, Instituto Agronomico. Comparative plots of each variety were harvested after 3, 4, 5, 6, 7, 8 and 9 months of vegetation, the product being then examined for the following characters : a) Total yield b) Number of roots c) Average weight of the potates d) Production of different grades e) Qualities of the fresh roots f) Culinary value of the sweets potatoes The yield after three months of vegetation was very small for the four varieties, but increased considerably in the later harvests. The variety Napoleão attained its highest yield after six months, being early; Roxa yielded most after seven months, being medium early, and the varieties Russia and Viçosa were late, giving their maximum yield only after eight months. The last named variety, in spite of occupying third and fourth position as regard to yield up to the fifth harvest (seven months), exceeded greatly the others at the eight and nine month harvests. The number and average weight of rcots varied according to the variety, and influenced the yield in different ways. The increase in yield of the variety Roxa resulted from an increase in the number of rcots, the average weight of these remaining practically the same at the various harvests. The var. Napoleão, on the other hand, increased in yield as a result of an increase in the weight of the rcots, the number of these not varying significantly at the success ve harvests. Both factors influenced the yield of the var. Russia and Viçosa, especially the increase in weight of the roots. Grading ihe product in six different sizes showed that the yield of the var. Roxa is predominantly of small sized sweet potatc es ; the var. Russia has medium roots. Napoleão has large rcots and Viçosa, very large ones. Other characters of the roots as shape, color, etc., were also studied, and culinary te sts were made with fresh sweet potatoes and with roots that had been cured under the sun.
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