prilagođeno pretraživanje po punom tekstu

ŠUMARSKI LIST 5-6/2014 str. 53     <-- 53 -->        PDF

photosynthetic and transpiration rates (P/T). Light conditions for photosynthesis were set using the LCpro+ light unit, which emitted photosynthetically active radiation (PAR) at 1 000 μmol m2 s1. The air supply unit provided a flow of ambient air to the leaf chamber at a constant rate of 100 μmol s1. Temperature, humidity and CO2 concentration were at ambient levels.
Concentrations of acetone extracted leaf pigments were assesed by spectrophotometry (Wettstein, 1957). Pigment concentrations were calculated using 9 replicates and expressed as mg · g1 of dry plant weight. All analyses were conducted on leaves at lower branches, 1–1.5 meters above the soil surface.
Precipitation and temperature data were obtained by the Republic Hydrometeorological Service of Serbia on the Meteorological stations closest to the measuring localities. Precipitation was calculated as a total sum during four weeks before each measurement. Temperature was calculated as a daily average, using data collected during four week period before each measurement.
All data were analyzed using Duncan’s multiple range test at the level of significance p<0.05. Values shown are arithmetic means. Significance level used was p<0.05. The average values shown in table columns followed by the same letter did not differ significantly. Linear correlations (r) were calculated between measured parameters using average values obtained at each survey locality.
The rate of photosynthesis Intenzitet fotosinteze
At localities Vidlič and Fruška gora, beech had the highest photosynthetic rate at the end of June (Table 2). CO2 assimilation was significantly reduced further during the vegetation season, in August on Fruška gora, and later in September also on Vidlič. Lowest photosynthetic rates were measured in September, after a drought period, also on spruce at Tara, and Kopaonik where the highest CO2 assimilation was determined in August. (Table 3). However, this dynamic was not established by results obtained on Kopaonik for beech, and on Tara for fir.
The rate of transpiration Intenzitet transpiracije
Comparing the measurements made on Vidlič and Fruška gora at the end of June with those made at the beginning of September, it could be observed that the rate of the transpiration decreased significantly (Tables 2 and 3). At Kopaonik, it was at its highest in September, while on Tara it depended on analyzed species.