DIGITALNA ARHIVA ŠUMARSKOG LISTA
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 ŠUMARSKI LIST 5-6/2015 str. 35     <-- 35 -->        PDF leaf (f=24,89 mm) were in population B (Table 1). Population D has the largest angle between the first vein and horizontal line (d=49,12o), population C has the largest width of leaf 1 cm from the top (e=5,67 mm). According to the average number of nerves on the left and on the right side of a leaf (h=6,07 and i=6,19) population C stands out, while in other populations the average number of nerves from both sides of a leaf is 5. The parameter e has the highest variability (21,4%), unlike the parameter b (5,04%) which has the lowest variability. Relative standard deviation of other parameters is in the range of 7–13%. In total the highest variability is shown in population A (11,15%) and the smallest in population D (8,41%). Statistically significant differences are recorded between test trees within each population, but there were no statistically significant differences between populations for most of measured parameters (Table 2). Parameters b, d, h and i are significant for p-value <0,01 while parameter f for p-value <0,05. Furthermore Tukey’s HSD test (table 1), that has been performed between populations, has determined which particular population is different in specific parameters, grouping populations with similar characteristics in same homogenous group. According to values of parameters b, d and h Tukey’ test group populations into three different homogenous groups, showing the highest differentiation between studied populations, while according to values of parameters f and i populations were grouped just into two different homogenous groups. The populations A is the one that mostly separates in different homogenous group from other populations. According to the dendrogram cluster analysis (Figure 3) of analyzed morphometric parameters it is clear that morphometric parameters are most similar between populations B and D. These populations are grouped on the lowest distance, while population C is very close to them. These three populations form a cluster, followed by population A which is on the highest distance. Discussion Rasprava Values of leaf parameters in this study are comparable with values given by Fitschen (2002) and Roloff (2006), where the leaf length is 5–12 cm, leaf width 4–10 cm and petiole length 2–6 cm. If we compare the obtained results with the results given by Tucović (1965) who reported leaf length in the range 89,28 – 94,80 mm, width 98,73 – 116,19 mm and petiole length 47,79 – 55,29 mm, it could be seen that leaf length and petiole length of studied populations are in this range, while leaf width is smaller from this range. Krstinić et al. (1997), Romanić (2000), Kajba et al. (2002), Bruce et al. (2010) did research of black poplar leaf variability along the Drava and Sava River in Croatia, Drava and Mura River in Slovenia, compared to their data, it is evident that the morphometric parameters of the black poplar leaf in its natural habitat in Vojvodina area are much higher. But we must take into consideration that reasons for these differences, beside the obvious genetic and environmental factors, could be that for mentioned researches leaf samples were taken only from short shoot. Observed characteristics are not equally under the genetic control. In general length and width of leaf are characteristics that are considered to be the most plastic one which are partially under genetic control (Hovanden and Vanden Schoor 2004). Given that the parameters that had a lowest variation (b, a and g) are considered as one under strong environmental influence (van Dam 2002, Krstinić et al. 1997), this indicates existence of similar environmental conditions between populations. The one that have highest variations (e, c, f and d) are considered to be under strong genetic control and less by the environmental factors (Kajba and Romanić 2002; Romanić 2000; Krstinić et al. 1997), which indicate a possible use of these parameters for estimation of intrapopulation and interpopulation variability, as well as to research the introgression of genes of other poplar species in local population of the European black poplar (Kajba and Romanić 2002).