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ŠUMARSKI LIST 1-2/2012 str. 19     <-- 19 -->        PDF

Ž. Škvorc, K. Sever, J. Franjić, D. Krstonošić, M. Poljak: INTENZITET FOTOSINTEZE I VEGETATIVNI ... Šumarski list br. 1–2, CXXXVI (2012), 7-17


tremely low, while the control plot was averagely supplied with physiologically
active phosphorus. Both plots under study featured accessible potassium
levels on the lower margins of an average supply. The humus content in the
studied plots was very low, especially in the chlorotic plot.


Statistically significant difference in the measured values of water potential
of the plants grown in the plots was determined only during noon measuring
throughout July. In August and September, statistically significant
differences in the measured values of water potential were not determined
(Table 3).


All the parameters of the vegetative growth of the plants under study which
were grown on the control plot had statistically significant higher values compared
to the plants grown on the chlorotic plot, except for the number of primary
branches, which showed no statistically significant differences between
the two studied plot trials (Table 4). Leaf surface index, value of which was
taken in the middle and near the end of the vegetative cycle, was statistically significantly
higher in the control plot than in the chlorotic plot (Figure 2).


There was statistically significant difference in the intensity of photosynthesis
measured on spring leaves of studied plants between the control and the
chlorotic plot. The intensity of photosynthesis on the control plot was 28.4
µmol CO2m-2 s-1, while its value on the chlorotic plot was 19.3 µmol CO2m-2 s-1.
Content index values of total chlorophyll in the leaves of the studied plants
were statistically significantly different regarding the plots under study, no
matter whether the measuring of chlorophyll content was conducted on spring
or summer leaves (Figure 4).


Regression analysis determined a high positive correlation between the
content index of total chlorophyll measured on spring leaves of studied plants
with the intensity of photosynthesis, leaf surface index, tree’s girth increment,
and also length and girth increment in the primary branches (Table 5). The
correlation between content index of total chlorophyll and tree’s height increment
was very weak.


The results of the study indicate that the soil’s chemical characteristics
have an effect on the photosynthetic activity and the concentration of chlorophyll
in the leaves of pedunculate oak. The higher values of the total chlorophyll’s
content index and the intensity of photosynthesis were recorded for
plants grown on the soil with a higher concentration of humus, nitrogen,
phosphorus and potassium. Positive correlations between the content indexes
of total chlorophyll in leaves and the intensity of photosynthesis, as well as
most of the parameters of vegetative growth, indicate the possibility of successful
application of chlorophyll measuring methods when determining vitality
of particular trees and forest stands of pedunculate oak.


Key words: Chemical composition of soil, chlorophyll content, leaf
area index, height increment, diameter increment