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Horticultura Brasileira

versão impressa ISSN 0102-0536versão On-line ISSN 1806-9991

Resumo

LORENZO, Gabriel A; MASCARINI, Libertad  e  GONZALEZ, Mariel N. Effect of N doses on spectral reflectance, chlorophyll content and nutrients on gerbera plants. Hortic. Bras. [online]. 2017, vol.35, n.2, pp.278-285. ISSN 0102-0536.  http://dx.doi.org/10.1590/s0102-053620170220.

In soilless crop, nutritional management must ensure the concentration and balance of nutrients, in order to obtain high productivity and quality, while fine adjustment of fertilization contributes to reduce environmental impact. Under the assumption that (1) an optimum level of N can be determined for gerbera, which provides the maximum potential productivity, (2) that the N level can be detected through a nondestructive technique, such as crop reflectance, and (3) that variations occur according to season, the objectives of this study were 1) to determine the effect of different doses of N on soilless-grown gerbera, 2) to detect patterns of spectral reflectance which could predict nutritional deficiencies, and 3) to detect variations of response to N dose in different season. In a soilless gerbera cv "Sunway" cut flower crop, three doses of N were tested, and flower production, spectral reflectance, leaf area, nutrient and chlorophyll content in leaf were recorded. The annual production did not differ significantly (110-113 flowers/m2/yr), however differences in specific moments in relation to N dose were found, showing better results for the highest dose in spring (22 vs. 12 flowers/m2/months), but the medium dose showed better response in the autumn (12 vs. 5 flowers/m2/months), while no difference occurred in winter or such differences were not quantitatively important (2 flowers/m2/months). Linear models that were constructed from the spectral reflectance allowed us to estimate the chlorophyll content, nitrogen and leaf area index (LAI) in a nondestructive way. The LAI could serve as an index for the nutritional management, looking to keep about 3, 4 and 2 m2leaf/m2ground in autumn, winter and spring, respectively.

Palavras-chave : Gerbera jamesonii; nitrogen; multispectral radiometer; soilless culture..

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