Effect of Innovative Bio-Based Plastics on Early Growth of Higher Plants

Plastic particles are widespread in the environment including the terrestrial ecosystems. They may change the physicochemical properties of soil and subsequently affect plant growth. In recent decades, traditional, petroleum-derived plastics have been increasingly replaced by more environmentally friendly bio-based plastics. Due to the growing role of bio-based plastics it is necessary to thoroughly study their impact on the biotic part of ecosystems. This work aimed for the assessment of the effect of five innovative bio-based plastics of different chemical composition and application on the early growth of higher plants (sorghum, cress and mustard). Each bio-based plastic was tested individually. It was found that the early stages of growth of monocotyledonous plants were usually not affected by any of plastic materials studied. At the same time, the presence of some kinds of bio-based plastics contributed to the inhibition of root growth and stimulation of shoot growth of dicotyledonous plants. Two PLA-based plastics inhibited root growth of dicotyledonous plants more strongly than other plastic materials; however, the reduction of root length did not exceed 22% compared to the control runs. PBS-based plastic contributed to the stimulation of shoot growth of higher plants (sorghum, cress and mustard) at the concentrations from 0.02 to 0.095% w/w. In the case of cress shoots exposed to this plastic the hormetic effect was observed. Lepidium sativum turned out to be the most sensitive plant to the presence of bio-based plastic particles in the soil. Thus, it should be included in the assessment of the effect of bio-based plastics on plant growth.