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Open access

D. R. Fravel, D. M. Benson, and R. A. Reinert

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.

Open access

R. J. Lotstein, D. D. Davis, and E. J. Pell

Abstract

Potted plants of ‘Merit’ tomato (Lycopersicon esculentum Mill.) were grown from seed to maturity in controlled-environment chambers and exposed to charcoal-filtered air or 288-314 μgm-3 (0.11-0.12 ppm) SO2 during weeks 1-5, 6-10, or 1-10 beginning about one week after transplanting. Red ripe fruit harvested from plants exposed to SO2 exhibited a slight but significant decrease in ascorbic acid expressed on a dry-weight basis. SO2 induced significantly greater levels of foliar sulfur, but did not increase sulfur content of the fruit. Exposure of plants to SO2 did not affect fruit yield or quality factors including soluble solids, total solids, or ascorbic acid on fresh-weight basis. A multiple regression model revealed low but significant R2 values, indicating a weak and indirect, yet significant, association between plant sulfur content and fruit ascorbic acid.

Open access

C. A. Miller and D. D. Davis

Abstract

Pinto bean plants (Phaseolus vulgaris L. cv. Pinto 111) in the unifoliolate leaf stage were exposed for 3 hours to 0.8 ppm SO2, 0.25 ppm 03, or a mixture of the 2 pollutants at these concentrations at 15, 24, or 32° C. Foliage exposed to O3 alone developed adaxial stipple and leaves exposed to SO2 alone developed interveinal necrosis. The mixture of O3 and SO2 induced O3-type symptoms at 32° and SO2-type symptoms at 15°. Both symptom types were present at 24°. Some abaxial glazing or silvering was also induced by the mixture, and was most common at 15° and 24°. Ozone and SO2 each induced greater foliar injury at 15° or 32°, as compared to 24°. The mixture of O3 and SO2 induced greatest macroscopic foliar injury at 15°. The degree of adaxial vs abaxial leaf surface injury varied with temperature.

Free access

J.A. Sullivan, B.A. Hale, and D.P. Ormrod

Factorial experiments in two growing seasons in open-top field chambers with two or three O3 concentrations and two primocane-fruiting raspberry (Rubus idaeus L.) cultivars were used to obtain dose-response relationships describing the effects of seasonal O3 exposure on raspberry plant vegetative and reproductive growth. At the lower concentration (0.12 μl·liter-1), the response to O3 was nonsignificant. However, at 0.24 μl·liter-1, `Heritage' showed a significant decline relative to the control in cane height, node count, cane diameter, and dry weight. These changes were accompanied by a 52% decrease in yield, caused mainly by a reduction in fruit count. In contrast, vegetative and yield characters of the `Redwing' were not affected by O3.

Free access

G. Eason and R.A. Reinert

Eight Bush Blue Lake type snap bean (Phaseolus vulgaris L.) lines and cultivars with similar genetic backgrounds were container-grown to green-pod maturity in open-top field chambers while being exposed to chronic doses of 03 for 7 hours·day-1 for 42 consecutive days. Treatments included charcoal-filtered air, nonfltered air, and 0.02, 0.04, or 0.08 ppm O3 added to nonfiltered air. Visible injury was estimated during the 2nd week of exposure and compared to the green pod yield data. The presence of four yield response groups, as determined via regression analysis, indicated the presence of variation for 03 sensitivity in the germplasm pool, but all eight lines were O3 - sensitive with yield losses at 03 levels exceeding a 7-hour daily mean of 0.085 ppm. Foliar injury may be a good indicator of general yield loss; however, estimates of visible injury lack the precision necessary to distinguish subtle differences among a collection of O3-sensitive snap bean lines.

Free access

Patrick M. McCool and Robert C. Musselman

Almond (Prunus amygdalus Batsch cv. Nonpareil), apricot (Prunus armeniaca L. cv. Royal Blenheim), and peach [Prunus persica (L.) Batsch cv. Halford] grafted nursery stock seedlings were exposed once per week for 4 hours to a maximum O3 concentration of 0.25 μl·liter-1 in field exposure chambers. Exposures were repeated for a total of 4 months in 1986 (year 1) and 1987 (year 2). Trunk caliper, number of shoots, and net growth (total seasonal weight increase) were measured at the end of each year. Almonds appeared to be the most sensitive to O3. Almond seedlings exhibited extensive foliar injury from O3, while apricot and peach seedlings were relatively insensitive. Total net growth of O3-exposed almond was reduced during both years relative to the controls and an impact on caliper was evident after year 2. Apricot seedlings exposed to O3 developed a thinner trunk but more shoots than the controls in both years. Peach tree seedlings exposed to O3 had fewer shoots than the controls at the conclusion of year 2 but thicker trunks after both years. No significant difference in variance or shape of distribution of net growth within the treatment populations between O3-exposed seedlings and controls was detected for any of the three fruit crops. The impact of O3 on young, nonbearing perennial fruit crops may be most evident in specific growth characteristics, such as net growth or trunk caliper.

Free access

Richard A. Reinert and Gwen Eason

Identification of genetic control of ozone (O3) sensitivity is desirable for selection of plant cultivars which are indicators of O3 stress. A cross was made between two cultivars of snap bean (Phaseolus vulgaris L.), `Oregon 91' (P1) and `Wade Bush' (P2), an O3-sensitive and O3-insensitive cultivar, respectively. Ten genetic populations (generations), `Oregon 91' (P1), `Wade Bush' (P2), F1, F2, backcrosses to both parents, and all reciprocal crosses, were field planted in each of two summers and evaluated for injury to O3. Ozone responses for the reciprocal crosses were not significantly different for any generation, so injury ratings from the reciprocal crosses were combined for each generation to provide six populations (P1, P2, F1, F2, BC1, and BC2) for analysis. When components of genetic variation were estimated from the six generations, additive genetic variance was the most important component in the total genetic variance available, although dominance variance was also a significant component. There was an inconsistency in the magnitude and the direction of the factors contributing to the dominance effects and also a large environmental component making up the phenotypic variance. Estimates of broad-sense heritability and narrow-sense heritability were 60% and 44%, respectively. Results suggest that O3-sensitive and O3-insensitive selections could be screened and evaluated in an ambient O3 environment. Several generations will be necessary, however, to develop `Bush Blue Lake' type selections that vary only in sensitivity to O3.

Free access

Gwendolyn Eason, Richard A. Reinert, and James E. Simon

Three watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] cultivars with different ozone (O3) sensitivities were grown in a charcoal-filtered greenhouse and exposed in continuous-stirred tank reactor chambers to five levels (0, 100, 200, 300, or 400 nL·L-1) of sulfur dioxide (SO2) in the presence (80 nL·L-1) or absence (0 nL·L-1) of ozone (O3) for 4 hours/day, 5 days/week for 22 days. In the presence of O3, SO2 increased foliar injury in all three cultivars, but the impact was greatest for the most O3-sensitive cultivar, `Sugar Baby,' moderate for `Crimson Sweet,' and least for the least O3-sensitive cultivar, `Charleston Gray.' For all cultivars, SO2 intensified O3 suppression of leaf area for the first seven mainstem leaves and of dry weights for aboveground and total plant tissues. Root dry weight was independently suppressed by both pollutants, and the root: top ratio was linearly suppressed by SO2 alone. Sulfur dioxide combined with O3 can be detrimental to crop species such as watermelon. Thus, the potential for SO2 phytotoxicity should not be summarily dismissed, especially in the vicinity of SO2 point sources where O3 co-occurs.

Open access

J. Pawloski Sinn and E. J. Pell

Abstract

Greenhouse-grown ‘Kennebec’ and ‘Atlantic’ potato (Solanum tuberosum L.) plants were exposed twice-weekly for 5 hours to 380 μg·m−3 (0.2 ppm) NO2 throughout their growing season. NO2 accelerated the rate of leaf abscission and reduced tuber number, weight, and dry matter percentage. NO2 was absorbed by exposed plants, as reflected by an increase in leaf total N content, but did not affect the total glycoalkaloid (tga) status of potato foliage or tubers.

Open access

M. Simini, J. E. Simon, R. A. Reinert, and G. Eason

Abstract

Foliage of field-grown muskmelon (Cucumis melo L. var. reticulatus Ser.) is susceptible to injury induced by ambient concentrations of ozone. Foliar injury symptoms consisted of interveinal chlorosis of the adaxial surface of the leaf tissue followed by bleaching of the foliage and necrosis. Fully mature leaves were affected more than younger leaves. Controlled fumigations of muskmelon plants with known concentrations of ozone produced foliar symptoms identical to those observed in the field. A differential cultivar response to ozone is reported and potentially tolerant genotypes are identified.