Abstract
Performance of open-top chambers used for air pollutant effect studies on mature grapevines (Vitis labruscana Bailey cv. Concord) was evaluated. The chamber environment was characterized by somewhat higher air temperature and dew point and decreased light intensity and wind velocity compared with ambient conditions. Within the chambers, grapevines had slightly increased leaf temperature. No differences due to chambers were detected on vine stomatal resistance, leaf water potential, or the relationship between leaf temperature and incident radiation.
Abstract
Pictorial keys were developed to aid graders in quantifying leaf injury on plants exposed to high concentrations of hydrogen fluoride gas. The keys were based on a pretransformed rating scale of 1 (no injury) to 12 (death of leaf).
Abstract
Seedlings of 3 birch species were exposed to either 0.3, 0.6, 0.9, or 1.2 ppm SO2 for 1, 2, 3, or 4 hours. Stomatal conductance rate measurements of 10 plants were taken prior to and immediately following each exposure. The percentage of leaf tissue injured by SO2 was estimated 72 hours after exposure. Stomatal conductance rates of European white birch (Betula pendula Roth.) and yellow birch (B. lutea Michx. f.) increased after exposure to 0.3 ppm SO2 for 1 and 2 hours, and decreased in response to all other doses of SO2. Stomatal conductance rates of gray birch (B. populifolia Marsh.) increased only after exposure to 0.6 ppm SO2 for 1 and 3 hours and decreased in response to all other dosages. European white birch was slightly more susceptible to SO2than gray birch, whereas yellow birch was tolerant.
Abstract
Foliage of watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] is susceptible to injury induced by ambient concentrations of ozone. Injury symptoms consisted of a premature chlorotic mottle of leaf tissue, followed by stippling and bleaching of the foliage, and necrosis. Older, more mature leaves were more affected than younger leaves. There was a differential cultivar response to ozone, which identified potential insensitive genotypes.
Abstract
Seedlings of 13 species of woody plants were sprayed or their growing media was drenched with N-2-(2-oxo-l-imidazolidinyl) ethyl-N'-phenylurea (EDU). The chemical provided protection against fumigations with 0.2, 0.4, and 0.6 or 0.35, 0.55, 0.75, and 0.95 ppm ozone (O3) for 3 hr. EDU reduced or prevented O3-induced necrotic flecking, bronzing, and premature aging of sensitive leaves of Acer rubrum L., Be tula papyrifera Marsh, Fraxinus americana L., Gleditsia triacanthos L., Koelreuteria paniculata Laxm., Plantanus × acerifolia (Aid.) Willd., Syringa vulgaris L., and Tilia cordata Mill. Drench of the growing media was a more effective method of applying EDU than a foliar spray application. An elapsed time of 7 days between applications of EDU and 03 exposure increased significantly the effectiveness of the chemical. We observed no other physiological effects from application of EDU on the growth of the plants. Seedlings of Cedrus deodora (D. Don) G. Don, Cornus florida L. and Pinus strobus L., were quite insensitive to O3 so the effectiveness of EDU on them was difficult to evaluate. Seedlings of Paulownia tomentosa Steud. and Quercus alba L. exhibited little or no visible injury from the fumigations with O3.
Abstract
Grapevines (Vitis vinifera L. cv. Shiraz) were fumigated in open-top chambers with hydrogen fluoride for 64 days at mean atmospheric fluoride concentrations of 0.17 or 0.28 μgHFm-3. Other grapevines grown under ambient conditions in the vineyard or maintained in control chambers were exposed to 0.13 or 0.05 μgHFm-3, respectively. Leaves of grapevines exposed to 0.28, 0.17, 0.13, or 0.05 μgHFm-3 accumulated up to 85, 55, 20, or 11 μgFg-1, respectively. Foliar necrosis was observed on plants exposed to 0.28 μgHFm-3, but no injury symptoms were observed at 0.17 μgHFm-3 or in control plants. Grapevines growing under ambient conditions had significantly greater mean bunch weight, peduncle weight, number of grapes per bunch, and leaf protein levels than the fumigated treatments. However, these differences may be associated with a chamber effect rather than with an effect of fluoride on grapevines. No significant differences were found between treatments for grape potential alcohol content, fruit acids, number of bunches or grapes per vine, fresh weight of grapes, or leaf chlorophyll content, despite foliar fluoride concentrations in the highest fluoride fumigation level reaching 85 μgFg-1. No evidence was found of significant fluoride accumulation in berries or canes.
Abstract
An anti-oxidant chemical, EDU, was applied in the greenhouse as a soil drench or by stem injection to 2-year-old containerized seedlings 7 days prior to fumigation with 0.35 or 0.95 ppm ozone (O3) for 3 hr. EDU treatment reduced the appearance of O3-induced symptoms (surface bleaching, bifacial necrosis, and chlorosis) on the foliage of red maple, Acer rubrum L.; honeylocust, Gleditsia triacanthos L.; sweetgum, Liquidambar styraciflua L.; and pin oak, Quercus palustris Muenchh. Stem injection of EDU was significantly more effective than soil drench at the same concentration, although both treatments afforded some protection at the low O3 level (0.35 ppm). About 50 times more EDU was required for comparable levels of O3 protection using soil application as opposed to stem injection. Honeylocust showed the greatest physiological response to EDU as evidenced by changes in root, stem, and leaf dry weight of stem-injected seedlings. All 4 species showed some sensitivity to O3 at 0.95 ppm in the absence of EDU. Chemical name used: N-[2-(2-oxo-1-imidazolidinyl)ethyl]-N’-phenylurea (EDU).
Abstract
Seedlings of ‘Fantastic’, ‘Homestead 24’, ‘Walter’ and ‘Heinz 1439’ tomato (Lycopersicon esculentum Mill.) were exposed to ozone 6 times between the 2nd and 5th week after emergence. Early total, marketable, and U.S. No. 1 yield were reduced when plants were exposed to 40 pphm ozone for 2 hours for all cultivars, except for ‘Walter’ in one trial. Early marketable yield of the most sensitive cultivar, ‘Fantastic’, was reduced an average of 14.7 metric tons/ha per year at 40 pphm ozone for 2 hours. Effect on early yield of 10 pphm ozone for 8 hours and 40 pphm for 1 hour was influenced by cultivar and year. Early yield was affected more by ozone concentration than by dose. Season marketable yield was unaffected by early acute ozone fumigation except for ‘Homestead 24’ at 40 pphm ozone for 2 hours in 1976. Fruit quality and fruit weight were not appreciably influenced by acute ozone exposure.
Abstract
Thirty-nine cultivars of marigold (Tagetes spp.) were exposed to sulfur dioxide to determine their relative sensitivity. Flowering plants were fumigated at 1 ppm SO2 for 4 hours or at 2 ppm SO2 for 2 hours. The average foliar injury for all leaves on individual plants ranged from 42.3% for ‘Crackerjack Mix’ at 2 ppm SO2 to 0.0% for ‘Cupid Yellow’ at 1 ppm SO2. Foliar necrosis appeared as a gray to white marginal and/or interveinal scorch 1 day after exposure. There was a tendency for interveinal necrosis to be near the midvein. The extra-floral nectaries which line the leaf margins of marigold were scorched in 15 of the 39 cultivars. This injury may be of diagnostic value. Sepals were very sensitive to SO2. Sepal injury appeared as a pinpoint scorch and as tip burn, and was apparent in some cultivars when no foliar injury occurred.
Abstract
A single 4 hour exposure of shore juniper, Juniperus conferta Parl., to 0.3 ppm O3, alone or in combination with 0.15 ppm nitrogen dioxide and/or sulfur dioxide, produced a significant number of small (<3 mm), elongate, tan foliar lesions 2 to 4 days after exposure. The injury symptoms were not identical to those associated with shore juniper decline.