Saturday, March 5, 2016

Assessing nitrogen requirements of wheat crops with a chlorophyll meter in the Southwestern Pampas

A chlorophyll meter is a promising tool for monitoring the status of N through the green index (IV). The hypothesis was that estimates from the use of a chlorophyll meter would be 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 objective was i) to determine IV sensitivity to predict total dry matter (MST) and grain yield, protein content and N-uptake, and ii) to evaluate N-availability at planting to establish reference plots without N deficiencies by using a chlorophyll meter at different stages of wheat cultivation and comparing field tests with a pot experiment. In 2010, a nitrogen fertilization trial was conducted in pots, while in 2011 and 2012 the trials were conducted on two sites in 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 settings (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 setting (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.

Key words Green index; ACA 303; Sub-humid Region
Martínez J.M., J.A. Galantini, M.R. Landriscini. 2015. Diagnóstico de fertilidad nitrogenada en trigo con la utilización de un clorofilómetro en el Sudoeste Bonaerense. Ciencia del Suelo 33(1) 31-43.
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