The Standardization of Poa Annua as an Indicator of Smog Concentrations. I. Effects of Temperature, Photoperiod, and Light Intensity during Growth of the Test-Plants.

THE BIOLOGY OF CANADIAN WEEDS.: 37 Poa annua L.

“…Poa annua is reported as sensitive to smog (Middleton et al 1950) and has been used as an indicator of injurious levels of air pollutants in parts of the U.S.A. (Juhren et al 1957 The effect of the grazing animal on P. annua has been reviewed by Wells (1974b Gibeault (1966a) also states that P. annua wTll survive, produce seedheads and spread more vigorously when mown at a close cut (0.5-1.0 cm) than when mown at 6-7 cm in a mixed sward.…”

Protection of Plants Against Airborne Oxidants: Cucumber Seedlings at Extreme Ozone Levels

“…P, as presented, is the probability that the test sample (chemical treatment) and the control sample (no chemical treatment) could( have been drawn from a common distribution. (10), hence the results reported here can only be considered on a comparative basis with reference to the growth and treatment conditions employed. (17,18,19 A comparison of root immersion, whole seedling immersion, and aerial application showed that protection of the aerial portion of the plant can be effected by compounds supplied entirely through the roots.…”

Stomatal Action in Plants as Related to Damage From Photochemical Oxidants

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A review of the literature indicates that the stomates of leaves must be open for smog damage to occur (3,7,8,9,11). However, there is no direct relationship between degree of opening and extent of injury, nor has it been proven that injury is prevented when the stomates are closed.

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