American ginseng (Panax quinquefolius L.), was injured by exposure to 20 pphm ozone and/or 50 pphm (v/v) sulfur dioxide for 6 hr daily for 4 days. Ozone induced upper surface leaflet stippling along the veins and interveinaily, and sulfur dioxide induced mild chlorosis to irregular necrotic areas. Ginseng was less sensitive to ozone and as sensitive to sulfur dioxide as ‘Cherry Belle’ radish (Raphanus sativus L.) and ‘Bel W-3’ tobacco (Nicotiana tabacum L.).
Crosses and subsequent segregation between inbred lines of ‘National Pickling cucumber (Cucumis satirus L.) resistant to acute exposure to sulfur dioxide, and the sensitive ‘Chipper‘ cucumber indicated that resistance was dominant and may be controlled by a single gene.
Eight cultivars of poinsettia, Euphorbia pulcherrima Willd. ex Klotzsch., were exposed to sulfur dioxide under controlled-environment conditions. A new cultivar, ‘Ruff & Reddy’, showed the most overall tolerance while ‘Rudolph’ and ‘Mikkel Blaze’ were least tolerant. The bracts of ‘Annette Hegg’ were injured most by sulfur dioxide, whereas the bracts of ‘Ruff & Reddy’ and ‘Eckespoint C-1’ were not visibly injured at the dosage levels tested. The wide range in tolerance to SO2 among the 8 different genotypes indicates a potential for breeding and selection of tolerant cultivars.
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.
Clusters of four varieties of table grapes were packed in TKV lugs and fumigated with 4, 6, or 8 Deccodione Smoke Tables (DST) for a period of 30 minutes in a fumigation chamber. After fumigation, inoculum of Botrytis cineraria was placed among the berries in the clusters in predetermined locations. Fruit was stored at 0C and high relative humidity for up to 16 weeks. Fruit was examined at 4, 8, 12, and 16 weeks of storage. Decay control index, freshness of stems, and bleaching of pigments around the capstem was recorded at each evaluation time. Size of aerosol particles was determined. Satisfactory control of decay was obtained with 8 DSTs. Lower doses failed to give satisfactory decay control. Bleaching of capstems typically seen with sulfur dioxide fumigation was not noticed with DST fumigation.
Botrytis cinerea and rachis browning as a result of desiccation are the two main factors that reduce table grape postharvest quality ( Nelson, 1985 ). The means for preventing decay during storage is the use of sulfurdioxide (SO 2 ), which was first tried
market availability of Vidalia onions from May to September ( Boyhan et al., 2008 ). Sumner (2000) reported good quality Vidalia onions after 7 months of storage under controlled-atmosphere storage. Sulfurdioxide is not used in onion storage in Georgia
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.
Two-year-old containerized seedlings of American sycamore (Platanus occidentals L.) were treated with maleic hydrazide (MH) before, after, or in the absence of sulfur dioxide (S02) fumigation. Exposure to S02 did not reduce the effectiveness of MH in controlling regrowth of this species. A strong negative linear trend was observed between SO2 concentration and sprout growth, either with or without MH treatment. In all instances, exposure to 1.0 ppm S02 resulted in high levels of phytotoxicity.
Three-year-old `Valencia' orange [Citrus sinensis (L.) Osbeck] trees were exposed to air pollutants for 4. years in open-top field chambers to determine the chronic effects of ambient oxidants (primarily ozone) or sulfur dioxide (SO2) on fruit yield and quality and tree growth. Ozone concentrations averaged 0.012,0.040, and 0.075 ppm for 0800 to 2000 hr during April to October for filtered, half-ambient, and full ambient oxidant chambers. Sulfur dioxide was applied continuously at 0.09 ppm. Oxidant and SO2 effects were only marginally significant, as there was considerable variability in response among individual trees and between years. Across two “on” production years, yields were 31% lower with ambient oxidants, 11% lower with half-ambient oxidants, and 29% lower with sulfur dioxide compared to filtered air. Number of fruit per tree was reduced by ambient oxidants and SO2. Individual fruit weights were reduced by ambient oxidants, but no other fruit quality characteristics showed definite responses to ambient oxidants or SO2. Ambient oxidants had no effect on yield or quality of fruit during one “off' production year. Neither ambient oxidants nor SO, affected tree growth.