A NOVEL METHOD TO EVALUATE THE PHYTOTOXIC POTENTIAL OF LOW OZONE CONCENTRATIONS USING POPLAR CUTTINGS

Six-week-old rooted cuttings of Populus nigra L. 'LOENEN' and Populus maximowiczii Henri X Populus nigra L. 'ROCHESTER', differing in their phenomenological sensitivity to O3, were submitted to low concentrations of O3, NO(x), and SO2. Exposure was performed in open top-chambers from 25.5. until 6.7.1988. Comparing the response of the two poplars by 77 biochemical criteria the macroscopic O3- sensitivity of 'LOENEN' was clearly reflected in changes of the pool sizes of the different nonstructural carbohydrates, polyols, and phenolics of the leaf-lamina, petiole, shoot-axis, and roots. In contrast, both varieties revealed the same response to NO(x)/SO2-mixtures. It can be concluded that 'LOENEN'-together with 'ROCHESTER'-poplars as controls, are an appropriate system to specifically indicate O3 in a mixture of air pollutants.