Silva Balcanica 22(1): 57-65, doi: 10.3897/silvabalcanica.22.e58528
Effect of wastewater sludge treatment on early growth and physiological responses of willow (Salix spp.) and poplar (Populus spp.) pot-grown plants
expand article infoIvaylo Tsvetkov, Nikolina Tzvetkova§, Svetla Marinova|
‡ Forest Research Institute, Bulgarian Academy of Sciences, Sofia, Bulgaria§ University of Forestry, Sofia, Bulgaria| Institute of Soil Science Agrotechnology and Plant Protection “N. Poushkarov”, Sofia, Bulgaria
Open Access

Combining biomass production from fast-growing woody species with wastewater treatment is an attractive concept from the economic, energy and environmental points of view. A pilot experiment on study-ing the effect of wastewater treatment on the early growth and initial physiological responses of willow and poplar plants was carried out in greenhouse conditions. The survival, height growth, net photosyn-thesis, stomatal conductance and transpiration of two hybrid clones of black poplar (Populus x euroameri-cana (Dode) Guinier) (I-214 and I-45/51) and white willow (S. alba L.) pot-grown plants treated with different doses of agrochemically characterised wastewater sludge were studied during the establishment year. The height growth and number of resprouted willow shoots were also measured during the second year after cutting, at the end of the vegetation season. While the early growth height of poplar clones was markedly affected by the clone origin and wastewater sludge treatment, the latter did not considerably influence the height of the willow plants either during the establishment and the following year, but essentially increased the number of resprouted shoots during the second vegetation season. The rate of CO2 assimilation of willow plants was significantly influenced by the wastewater sludge treatment, with plants grown at the higher doses displaying higher photosynthetic performance. The application of wastewater sludge had no essential impact on the values of the physiological parameters of the poplar plants, but particular responses were found among the clones.

Biosolids, fast-growing woody species, photosynthesis, soil conditioning