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ŠUMARSKI LIST 5-6/2012 str. 52     <-- 52 -->        PDF

found in some desert plants exposed to crude oil contaminated soil (Malallah et al., 1998), Vigna unguiculata plants (Achuba, 2006), as well as in Amaranthus hybridus affected by engine oil (Odjegba and Sadiq, 2002). However, crude oil had no significant effect on the photosynthetic pigments in Halophyla ovalis (Ralph and Burchett, 1998).
Dark Respiration Rate (DRR) – Disanje
Dark respiration rate was increased by 5, 25, 50 and 100 % crude oil treatments in poplars with respect to control (Table 3.). Dark respiration plays the crucial role in the regulation of cell metabolism being a basic source of energy resources (Vassilev and Yordanov, 1997). Species growing under stress conditions have higher rates of leaf respiration than species in less stressful environments due to activation of metabolic defense and repair systems (Wright et al. 2006). Old leaves are reported to have lower respiration rates and repair capacities (Di Baccio et al. 2003). The intensity of dark respiration has a significant importance in dry mass accumulation because half of all the photosynthates produced per day are respired in the same period (Lambers, 1985).
Results of analysis of variance and F values (Table 5.) show­­ed high significance (p>0.01) of interaction between treatment and clone for all investigated parameters except concentration of carotenoids in leaves of poplar clones. Effect of treatments on carotenoids concentration was not significant, while significance of interaction was evident (p>0.05). This may be due to the fact that carotenoids do not play primary role in photosynthesis, compared to the chlorophyll.
Results showed significant differences between investigated clones of poplars exposed to crude oil treatments. The 5% treatment (578 mg g–1 of TPH) slightly affected biomass pro­duction of poplar clones, although significant differen­ces were recorded at treatment 25% (2812 mg g–1 of TPH). The highest decrease of fresh biomass was recorded in clone 9111/93.
The effect of crude oil contamination on physiological processes of poplar clones was observed in all investigated parameters with exception of the carotenoids concentration.
On the basis of these results, poplar clones ´Bora´ and ´Pannonia´ showed potential for growth on crude oil contaminated soils.
All investigated parameters could be used as markers in selection of poplar clones for crude oil phytoremediation.
Success of phytoremediation is not only result of type of con­tamination and its level or soil properties and microorganisms´ abundance but also the proper selection of clones and cultivars plays significant role. Considering this fact to­gether with obtained results, further research directed to the investigation of plant-microorganisms-soil interaction including clonal selection is required.
This paper was realized as a part of the project ´´Studying climate change and its influence on the environment: impacts, adaptation and mitigation´´ (43007) financed by the Ministry of Education and Science of the Republic of Serbia within the framework of integrated and interdisciplinary re­search for the period 2011–2014.
Achuba, F. I. 2006: The effect of sublethal concentrations of crude oil on the growth and metabolism of cowpea (Vigna unguiculata) seedlings. The Environmentalist 26: 17–20.
Agbogidi, O. M., P. G. Eruotor, S. O. Akparobi, G. U. Nnaji 2007: Evaluation of crude oil contaminated soil on the mineral nutrient elements of maize (Zea mays L). Journal of Agronomy 6(1): 188–193.
Agrawal, S. B. 1992: Effect of supplemental UV–B radiation on photosynthetic pigment, protein and glutathione contents in green algae. Environmental and Experimental Botany 32: 137–143.