Az Eszterházy Károly Tanárképző Főiskola Tudományos Közleményei. 2004. Sectio Biologiae. (Acta Academiae Paedagogicae Agriensis : Nova series ; Tom. 25)

Makrai, L., Dulai, S., Polyánka, H., Ertli, T. and Lehoczki, E.: Monitoring of the Functional State of Beds of Common Reed (Phragmites australis) in Shallow Lake Balaton (Hungary) by Means of Chlorophyll Fluorescence Studies

142 Makra, L. et al. the measurements were made, the samples were placed in water taken from the location of the sampling and stored in a dark room for a minimum of 5-6 hours. Fluorescence induction measurements were the carried out on the 3rd or 4th leaves from the apex. From the sample leaves kept in the dark, discs in 11 mm in diameter were cut from the upper third of the leaves, and placed in specially-designed sample boxes. Chlorophyll-a fluorescence measurements The fast and slow chlorophyll fluorescence induction kinetics (Kautsky effect) were recorded in the 730 nm region on the upper surface of the leaf discs after a 30-min additional dark adaptation in the sample boxes, using the computerized apparatus described by Szigeti et al. (1988). The controlling system allows the simultaneous measurement of fast and slow fluorescence transitions on the same leaf disc. Fo (initial fluorescence), Fi (intermediate fluorescence), Fm (maximum or peak fluorescence), and Fss (steady-state fluorescence) were measured on different time-scales. The quantum flux density of PAR at the surface of the samples was 185 |imol m~

2 s"

1. Recording of the slow fluorescence kinetics for 5 min was sufficient for the steady-state level to reached and for determination the ratio of the fluorescence decrease Rfd as (Fm-Fss)/Fss). Gas-exchange measurements Photosynthetic CO2 assimilation-light curves and chlorophyll fluorescence were measured on the same part of Phragmites leaves. C0

2 assimilation was measured in normal air (345 ppm C0

2 and 21% 0

2) with an infrared gas analyser (LCA-2, Analytical Development Co., Ltd., Hoddesdon, UK). The white light for the activation of photosynthesis was provided by a projector light source (projection lamp, Type 6423, Philips, Germany) through a heat filter (Melles Griot, Irvine, CA). The leaves were exposed for 10 min to white light of different intensities (from dark to 1500 fimol m"

2 s"

1 PAR) in a Parkinson leaf chamber (PLC-B, Analytical Development Co., Ltd., Hoddesdon, UK) and the C0

2 fixation was determined. The rates of C0

2 fixation were calculated by using the equations of Von Caemmerer and Farquhar (1981). Statistical analyses For comparisons of means, multivariate analysis of variance (MANOVA) and factorial ANOVA (were used, followed by the Tukey HSD test.