Carbohydrates concentration in leaves of potato plants affected by nitrogen fertilization rates
Palavras-chave:
Solanum tuberosum L.. Açúcares. Amido. Quarta folha. Correlação.Resumo
At poor conditions of nitrogen (N) in the soil, potato plants may accumulate starch in leaves and be indicative of N
nutritional stress. The objective of this work was to determine the effects of N rates (0, 50, 100, 200 and 300 kg ha-1 of N)
on the concentrations of carbohydrates (total soluble sugars-TSS, reducing sugars-RS, non-reducing sugars-NRS and
starch) in the fourth leaf (FL) of two potato cultivars (Asterix and Atlantic) and their critical levels (CL) associated to the
N fertilization rate necessary to obtain the maximum physical (MPE) and economic (MEE) efficiency of tubers. A
randomized block design with four replications was used in both experiments. On day 21 after plant emergence, four FL
were collected from four plants. Potatoes plants fertilized with low rates of N accumulated less TSS in leaves than those
properly fertilized. The opposite occurred with content of starch. The cultivars showed similar responses to five doses
of N in relation to contents of starch and TSS. However, the response to the increase in doses of N for RS, NRS and
Starch/NRS is cultivar-specific. The correlations between contents of RS, NRS and Starch/NRS with the starch and TSS
were dependent on the potato cultivar.
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