1980 Volume 15 Issue 4 Pages 155-162
It was studied with poplar cuttings (Populus × euramericana cv.'I 45/51') grown in filtered air greenhouse (F.A.) and non-filtered air greenhouse (n-F.A.) in the suburbs of Tokyo how photochemical oxidant of ambient air affected the poplar leaves of different ages. These results were as followed.(1) Number of days when the daily maximum concentrations of oxidant in non-filte ed air exceeded 15, 10 or 7 pphm, were 1, 13 and 51 respectively for 104 days exposure period.(2) The young leaves till about the 20th daya fter unfolding in n-F.A. had chlorophyll contents and photosynthetic rates similar to those in F. A.. But, in the mature aged leaves, chlorophyll contents and photosynthetic rates in n-F.A. declined greatly. There was a strong negative relationship between the sum of oxidant dose (from 6 a.m. to 6 p.m.) exposed from the 20th day after each leaf unfolded, and the ratio of chlorophyll contents (n-F.A./ F.A.× 100%) in poplar leaves of different ages. The strong positive correlationship was observed between chlorophyll contents and photosynthetic rates except for young age leaves still about the 20th day after unfolding.(3) Light saturation points of poplar leaves in F.A. and non-injured leaves in n-F.A. were 20-30 Klux, and those of visible injured leaves in n-F.A. were about 10 Klux. If net photosynthetic amounts per plant a day were calculated using the light-photosynthetic curves and leaf area of plant, the values in n-F.A. were half of them in F.A.(4) Dark respiratory rates of mature leaves without visible injury, and of lower leaves with visible injury in n-F.A. were higher than in F.A.(5) Reducing sugar contents of all leaf ages in n-F.A. were almost double in F.A.. Non-reducing sugar contents of all leaf ages in F.A. showed about 30 mg./g.d.w., but those in n-F.A. were lower than 10 mg./g. d.w. except for the 20th day age leaf.(6) Total and protein nitrogen contents of leaves were almost the same values in F.A. and n-F.A. till the 20th day after unfolding. But, in the mature aged leaves, those in n-F.A. were lower values than in F. A..
