Resumo

MARTINEZ, JUAN MANUEL; GALANTINI, JUAN ALBERTO  e  LANDRISCINI, MARÍA ROSA. DIAGNÓSTICO DE FERTILIDAD NITROGENADA EN EL SUDOESTE BONAERENSE MEDIANTE EL USO DE UN CLOROFILÓMETRO EN TRIGO. Cienc. suelo [online]. 2015, vol.33, n.1. ISSN 1850-2067.

The chlorophyll meter is a promising tool for monitoring the N status through the green index (IV). The hypothesis is that estimates from the use of a chlorophyll meter is more closely linked to the N harvested from dry matter than to wheat (Triticum aestivum L.) grain yield, which is affected by climate variability. The objectives of this study were to i) determine IV sensitivity to predict total dry matter (MST) and grain yield, protein content and N-uptake, and ii) evaluate N-availability at planting in order to establish reference plots for using a chlorophyll meter during different stages of wheat. In 2010, a nitrogen fertilization trial was conducted in pots, while in 2011 and 2012, the trials were conducted on two sites in the Southwest of the Pampas (SOB) under no-tillage. In two (Z22 y Z40) and three (Z22, Z40 y Z70) stages of the crop, chlorophyll meter readings were taken for the field and pot trials, respectively. The field prediction of MST and grain yield, protein content and N uptake with chlorophyll meter readings showed significant regressions with low goodness of fit (R² = 0.11 to 0.29). In the pot experiment, the prediction of N-uptake for the three sampled stages increased, without differences in slopes and with a high goodness of fit (R²=0.79). The chlorophyll meter would be a promising indicator of N-uptake by the crop; in sub-humid regions, however, it would not be an accurate tool to predict grain yield or protein content in wheat crops. Also, a chlorophyll meter would be useful to estimate the available N needed by the wheat crop and to determine the nutritional status of the plant.

Palavras-chave : Green index; ACA 303; Sub-humid Region.

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