Abstract
In order to study the effects of air pollutants, especially photochemical oxidants, on the plant growth, the poplar cuttings (Populus x euramericana cv. ‘145/51’) were grown in filtered air greenhouse (F.A.) and non-filtered air greenhouse (n-F.A.) in the suburbs of Tokyo. In filtered air, about 90% of the ambient photochemical oxidants were excluded.
(1) The shoot's height (H), diameter (D) and dry weight of poplar cuttings was respectively 216 cm, 17.3 mm, 211.69 g in filtered air and 143 cm, 11.7 mm, 82.73 g in non-filtered air at about four months after cutting in 1975.
(2) Growth ratio (RGR) and net assimilation ratio (NAR) of poplar cuttings were less in non-filtered air than in filtered air, but leaf area ratio (LAR) was more in non-filtered air.
(3) Number of leaves unfolded till 114 days after cutting was 65.2 in filtered air and 51.2 in non-filtered air. The maximum leaf area of plant was 332.2 cm2 in filtered air and 222.2 cm2 in non-filtered air.
(4) The foliage damage was observed on the mature leaf surface of poplar cutting in the non-filtered air greenhouse when the ambient oxidant was over 10 pphm, but was not in the filtered air. The damaged leaves dropped in the growing season. The number of dropped leaf was 20.4 in non-filtered air, but only 5.0 in filtered air till 114 days after cutting in 1975.
(5) There was a strong negative relationship between the ratio of growth amount (D2H%=n-F.A./×100) and oxidant concentrations occurred in poplar growing season from 1974 to 1978. Farther, there was a strong positive relationship between leaf damage index and oxidant concentrations occurred from 1975 to 1978.
