Bull. Spec. CORESTA Congress, Lisbon, 2000, p. 107, APOST6 (adjourned)

Estimation of the state of nitrogen nourishment of tobacco using the N-tester

University of Agriculture, Lublin - Institute of Agricultural Sciences, Zamosc, Poland.
The purpose of this work, based on a three years of field experiment, was to inspect whether it is possible to use a chlorophyll meter in fixing the nitrogen doses used in growing flue-cured tobacco. The relationship between the capacity of nitrogen and the capacity of chlorophyll constitutes the basis of the optical method, which is using the device called N-tester or chlorophyll meter. The contents of chlorophyll in leaves in SPAD (Soil Plant Analysis Development) units was rising since the second measurement till the upper parts ripening phase, and then was gradually falling down. The data of the chlorophyll meter was strictly and positively correlated with the dose of the fertilizer (r=0,96), with the yield (r=0,93), and with the capacity of nicotine (r=0,98) and protein in leaves (r=0,70),. The correlation between SPAD units and the share of light classes and the capacity of carbohydrates was negative during the whole vegetation period (r= - 0,90 and r= - 0,60). The dose of 30 kg N/ha was stated as an optimal nitrogen dose. While applying this dose the yield of leaves was relatively high and its quality was very good. The increase of the level of fertilization up to 45 kg N/ha caused a violent decline in the quality of leaves measured by the share of classes 1st and 2nd. The chlorophyll meter data from the fields with an optimal nutrition dose was from 330 to 380 SPAD during the growing time, when supplementary fertilizing can be used as well. At such a SPAD data using this fertilization seems superfluous. The chlorophyll meter can be used on a wide scale due to its relatively big precision and easy usage.