Recently, oat (Avena sativa L.) plants are cultivated as worldwide functional food. The
aim of this study was to analyse the response of photosynthetic apparatus of naked and hulled
oat cultivars grown under different nitrogen fertilization dosage as well as different weather and
soil conditions (different locations). Our analysis showed a significant influence of all studied
experimental factors i.e. location, year, nitrogen dosage, cultivar/strain, leaf position on some
selected chlorophyll fluorescence (ChlF) parameters and grain yield. Soil and climatic conditions/
environments had the largest and statistically significant contribution to the variability of the
analysed ChlF parameters, while the genotype (cultivar/strain) effect was the highest for grain
yield. For other effects, the values were much smaller. Our results suggest that chlorophyll
fluorescence measurements should be used in oat field experiments as a trustable and useful
tool to study the reactions of plants photosynthetic apparatus under natural environments
and to predict its yielding. Moreover, it can help to establish the optimal growth conditions for
individual cultivars, including fertilizers’ dosing.