Phytotoxicity of Materials after Sorption of Humic Substances from Raw Reject Water

The research aimed at the characterization of the value of two chosen adsorbents – opoka (OP) and autoclaved aerated concrete (AAC) before and after adsorption of humic substances (HSs) from raw reject water (RWR) as growth plant promoters. Four plants, including monocotyledonous Sorghum saccharatum (SS) and dicotyledons: Lepidium sativum (LS), Sinapis alba (SA), and Raphanus sativus (RS) were used to evaluate the phytotoxicity of adsorbents after the adsorption process.The project is aimed to develop inexpensive and environmentally friendly soil conditioners and plant growth promoters. Preparations after HS sorption (AAC_PS and OP_PS) inhibited the germination of mustard and stimulated the development of radish and sorghum. In the case of sorghum, higher concentrations resulted in high variability (high standard deviation value). This variability may result from the properties of the seed coat, which also serves as a filtering membrane. Differences in plant development also result from their environmental preferences. The observed phytotoxic effect on mustard and positive impact on radish and sorghum show that tested growth promoters are selective in their activity and can’t be applied in the case of each plant.