Resumo

GILETTO, Claudia Marcela; RATTIN, Jorge Edgardo; ECHEVERRIA, Hernán Eduardo  e  CALDIZ, Daniel Osmar. Nitrogen nutrition assessesment in new potato processing cultivars. Cienc. suelo [online]. 2006, vol.24, n.1, pp.65-75. ISSN 1850-2067.

The introduction and evaluation of new potato cultivar must be done in combination with a suitable management profile, in order to achieve improvements in yield, quality and profitability. A crucial aspect within this profile is nitrogen nutrition. During 2003/04 seasons nitrogen nutrition was assessed in potato processing cultivars (Innovator, Russet Burbank, Gem Russet and Bannock Russet). As diagnosis methods to estimate the nutritional state petiole dry matter nitrate-nitrogen concentration (N-NO₃ -BSp); petiole sap nitrate-nitrogen concentration (N-NO₃ -Jp), and leaf chlorophyll content (Green Index GI) were evaluated. Cultivars showed a different average concentration and N-NO₃ - BSp evolution, showing a differential response to nitrogen doses and application time. It was possible to relate N-NO₃ - BSp with soil characteristics. Independently of the cultivar, N-NO₃ - Jp was less stable during time than N-NO₃ - BSp, due to a higher sensitiveness to detect changes in the nutritional status of the crop. The GI was more affected by foliage color variation among cultivars than nitrogen fertilization; which confirmed that the GI should be used with a high N control plot per variety for proper comparisons. At 74 days after planting, the N-NO₃ - BSp was related with relative yield (RR) showing that the thresholds levels of 11 g kg ^-1, and of 1g L ^-1 to BSp and Jp, respectively, could be used as a reference to assess the nutritional status of new cultivars. However, no association was found between RR, GI and the nitrogen sufficiency index (NSI), when they were considered at tuber initiation and early tuber bulking.

Palavras-chave : Potato processing cultivars; Petiole nitrate; Green index.

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