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  • Author or Editor: Richard A. Reinert x
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Abstract

Air pollutants influence the growth, yield and quality of many horticultural crops. It is difficult to determine and evaluate the impact of air pollution on the horticulture industry for the following reasons: The variable environments in which horticultural crops are grown markedly influence the amount of foliar injury caused by air pollutants. The large number of cultivars within horticultural crop species contribute to the magnitude of understanding necessary to evaluate pollutant effects. Genetic, morphological and physiological differences among species and cultivars within species also influence foliar injury and plant sensitivity. The amount of economic loss in horticultural crops due to air pollutants varies from year to year. This variation is probably most directly related to daily and seasonal variations in ambient concentrations of air pollutants. Horticultural crops may be subjected to high pollutant concentrations at different stages of plant maturity. These different stages of growth and development may be differentially affected by pollutant concentration and thus influence yield. Past estimates of crop yield losses have been based primarily on assessment of visual injury. Presently, there is a lack of suitable methodology to assess air pollution impacts under field conditions. Open-top chambers (40, 60) are an improvement but better techniques are needed. Finally, air pollution research is published in a variety of scientific journals and some of these references may not come to the attention of horticultural scientists.

Open Access

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

Abstract

The radish cv. Cherry Belle was exposed to 5 pphm ozone and/or 5 pphm sulfur dioxide for 40 hr per week for 5 weeks and compared with controls grown in charcoal filtered air. Ozone and/or sulfur dioxide significantly reduced the plant fresh wt, leaf fresh wt, root fresh and dry wt and root length and width. The effects of the combinations of the 2 gases were additive except for plant fresh wt, root length and root fresh and dry weights where the effects were significantly less than additive. Low concns of ozone and sulfur dioxide can be significant factors in the growth and yield of radishes.

Open Access

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.

Free access

Abstract

Eight lettuce and 9 radish cvs. were exposed for 1.5 hr to 70 and 35 pphm ozone, respectively, and ranked according to their sensitivity. ‘Dark Green Boston’ was the most sensitive while ‘Great Lakes’ and ‘Black-Seeded Simpson’ were the least sensitive of the lettuce cvs. tested. ‘Cherry Belle’ was the most sensitive and ‘Icicle’ was the least sensitive of the radish cvs.

Open Access

Abstract

Twelve cultivars of tomato were exposed to 40 pphm ozone for 1.5 hr in separate morning and afternoon exposures to determine differences in cultivar sensitivity. Nearly all of the cultivars exposed in the afternoon developed more injury than similar cultivars exposed in the morning. Cultivar ranking, however, was the same in morning and afternoon exposures. ‘Roma VF’ and ‘Red Cherry’ were among the most sensitive cultivars tested and ‘Heinz 1439’ and ‘VF 145B’ were the least sensitive of the 12 tomato cultivars tested.

Open Access

Watermelon, Citrullus lanatus (Thunb.) Matsum & Nakai cv. Sugar Baby, were grown in the field as a fall crop in open-top chambers (OTC) in southwestern Indiana with either charcoal-filtered (CF) or nonfiltered (NF) air. Ozone and sulfur dioxide were continuously monitored in OTC and ambient air. There was a significant decrease in marketable yield by weight (19.9%, P = 0.05), percentage of marketable fruit by number (20.8%, P = 0.10), and total yield by weight (21.5%, P = 0.05) from plants grown in the NF air treatment compared with those grown in CF air. Ozone-induced foliar injury was significantly greater on plants grown under NF conditions. Ambient concentrations of 03 in southwestern Indiana caused foliar injury (P = 0.10) and significant yield loss to a fall crop of watermelons.

Free access