Physiological response of Miscanthus x giganteus grown in nutritionally poor post-military soil

Background: To determine the level of plant stress of second-generation biofuel crop Miscanthus x giganteus ( Mxg ) grown in poor quality post-military soils using physiological parameters; to identify impact of plant growth regulators (PGRs) on the stress reduction and to select the fluorescence indicators most suitable for quantification of stress. Plant fitness was quantified with non-invasive measurement of leaf fluorescence using 16 different indexes. Simultaneously visible stress signs were observed on stems and leaves and differences were revealed by microscopy of leaf sections. Results: Leaf fluorescence analysis, visual observation and changes of leaf anatomy revealed significant stress in all tested subjects . Besides commonly used F v /F m and P.I. (performance index), the fluorescence parameter T fm (time to achieve maximum fluorescence) seems to be rather sensitive and applicable for revealing finer differences. However, none of investigated parameters proved significant positive effect of PGRs on stress reduction. Conclusions: Measuring F v /F m , P.I., and T fm is a suitable method for revealing stress affecting Mxg in poor post-military soils. Since PGRs application did not reduce the stress level, direct application of soil amendments should be considered for stress reduction and improving the biomass quality.