Abstract
Diesel exhaust was used for CO2 enrichment of vegetable crops in inflated plastic houses. Fuel source and components of the recovery system crucially affected the elimination of other harmful gases. The absence of an activated charcoal filter and the use of fuel high in sulfur content increased ethylene, sulfur dioxide, nitrogen dioxide, and probably others. In the gas-added environment, as compared with the ambient one, lettuce grew more slowly, and leaf size and yield decreased in cucumber and eggplant. Plants were exposed to the gas-added environment for about 5 months, after which the system was discontinued. Plants did not recover, and symptoms continued despite discontinuing gas addition.
Table grapes cvs. Flame Seedless, Black Monukka and Canadice were fumigated with 2 levels of Deccodione smoke tablets for 30 minutes. Grapes were packed in TKV lugs with Botrytis inoculum planted among the clusters and stored at 0° C for up to 9 weeks. Size of smoke particles was determined. Fruit was evaluated at weekly intervals for decay and quality parameters. Deccodione residues on fruit were determined and found to be within acceptable limits set for this chemical. It was possible to store the grapes for up to 4 weeks at 0° C in good condition. Beyond this period effect of fumigation was lost. There was no bleaching of pigments around the capstem as is seen with sulfur dioxide fumigation. Storage for prolonged periods will necessitate increasing the dose of Deccodione tables and/or repeating the fumigation.
Abstract
Radish (Raphanus sativus L. cv. Cherry Belle) and marigold (Tagetes patula L. cv. King Tut) were exposed 3 times (every other day), for 3 hours each time to NO2, SO2, and O3, alone and in mixture at 0.3 ppm of each pollutant. Plants were exposed to the pollutant treatments at 3 ages. Radish was most sensitive to O3 at 19–23 days from seeding. The response of marigold to the individual pollutants was not dependent on plant age. Pollutant treatments containing O3 reduced radish root (hypocotyl) dry weight 48% per plant compared with plants exposed to treatments without O3. Interactions of NO2, SO2, and O3 on weight changes in marigold were significant. Sulfur dioxide, alone, reduced the dry weight of the marigold flower and roots, but the inhibitory effect of SO2 was reversed in the presence of NO2 or O3.
Abstract
The leaf roll-necrosis disorder has been identified in collections of lilac (Syringa vulgaris L.) in or near the cities of New York, Philadelphia, and Boston. Observed symptom differences among lilacs at 6 sites were largely quantitative, indicating the occurrence of incitants common to all locations. Activated charcoal and 4,4’-dioctyldiphenylamine filter chambers applied to branches reduced injury and provided corroborating evidence that air pollutants, including oxidant-type, were causal factors. Monitoring data from New York City and Philadelphia revealed progressively decreasing pollutant levels in recent years that coincided with decreases in severity of the disorder. Fluoride was not a causal agent, based on low levels in leaves. In experimental fumigations of lilac clones, although the results were inconclusive regarding identification of causal pollutants, ozone and sulfur dioxide induced some symptoms of the disorder. The occurrence of additional field symptoms suggested the involvement of other, as yet unidentified, phytotoxic pollutants.
Abstract
Scars caused by the ovipositional and feeding activities of the western flower thrips, Frankliniella occidentalis (Pergande), on ‘Thompson Seedless’ and ‘Calmeria’ table grapes, Vitis vinifera L., had no effect on many measurable quality attributes of the fruit. Scarred berries showed no apparent differences in size or average weight when compared to undamaged fruit. However, scarred ‘Thompson Seedless’ berries had a higher soluble solids content. The acid content was not affected by any type of scar and all fruit had soluble solids to acid ratios of at least 20:1. Scarring did not affect the weight loss of fruit in short-term storage at 0.6°C, and scarred berries were not injured by sulfur dioxide fumigation.
An Air Quality Learning and Demonstration Center has been developed within the Arboretum at Penn State Univ.. The Center provides opportunities where students (of all ages) and teachers (grade-school through to classes within the Univ.) can learn about air quality as one of our most important natural resources. A seasonally interactive display of air quality monitoring instrumentation, self guided walkways through gardens of air pollution sensitive plant species, innovative techniques for demonstrating the effects of air pollutants on plants, displays of recent research findings, industry supported displays of pollution abatement technologies, and a teaching pavilion are within the Center. A Pennsylvania Dept. of Environmental Protection air quality monitoring station with ozone, sulfur dioxide, nitrogen oxides, carbon dioxide, PM < 2.5 u mass and speciation samplers, and a complete meteorological station provide data on the immediate environmental parameters. These data are relayed to an LCD crystal display board that has been mounted on the outside of the monitoring building; visitors are able to see the various measures of the air quality on a real time basis. Pannier type fiberglass display panels provide understandings of the various facets of air pollution formation and transport phenomena, air quality monitoring methods, the functions of open-top chambers, foliar symptoms expressed by pollution sensitive plants within the bioindicator gardens, and the impacts of pollution on agricultural and forested ecosystems. Handicapped accessible walkways lead visitors throughout the Center to the Teaching Pavilion that easily accommodates 80 persons. The pavilion is equipped with drop down curtains, electric power, and internet connections.
Grape (Vitis vinifera) storage requires stringent control of gray mold caused by Botrytis cinerea. The commercial practice is dependent on sulfur dioxide (SO2) as a fumigant, which is applied by various means with well-known advantages and disadvantages. Many alternative technologies were developed over the years, most of them with limited efficacy or applicability. Modified atmosphere of table grapes suffers from a narrow threshold between control of gray mold and damage to the berries and stems due to high level of carbon dioxide (CO2) within the film-enclosed package. We demonstrated in the past that dipping table grapes in ethanol after harvest has a very pronounced effect on prevention of decay. However, ethanol does not leave a protective residue within the grapes, so it is not expected to prevent latent infections from developing decay nests during prolonged storage. However, if grapes of cultivar Superior were treated with ethanol and then subjected to a modified atmosphere using plastic films (Xtend), we achieved an additive effect and observed persistent control of gray mold without injury to the grapes. The advantage of this plastic film was mainly in its water conductance, which prevented accumulation of free water that is often the limiting factor in modified atmosphere packaging. This combination results in greater decay control, which is a prerequisite for commercial applicability. If undesired aftertaste did develop within the fruit due to the modified atmosphere, 1 day of exposure to ambient air was sufficient to dissipate it.
Abstract
Lettuce (Lactuca sativa L. cv. Grand Rapids) and radish (Raphanus sativus L. cv. Cherry Belle) plants growing at baseline environmental conditions were exposed to charcoal-filtered air, 0.40 ppm (v/v) ozone, and 0.80 ppm sulfur dioxide alone or in combination for 6 hours at 14 days from seeding. Analysis of covariance was used to account for significant within-treatment variation in plant growth. Covariates used were: planar leaf area (PLA) at 14 days for leaf area, fresh weight, and dry weight at harvest; plastochron index (PI) at 14 days for PI at harvest; and hypocotyl diameter for hypocotyl weights of radish roots at harvest. The covariates reduced the variability (standard geometric errors) of the response variables and increased the precision of statistical tests substantially for lettuce but much less for radish. For lettuce, the effect of the gas mixture on plant growth and foliar injury was less severe than that of the single gases. Radish plants, in contrast, exhibited no response to SO2 and the effects of O3 and the mixture on foliar injury and plant growth were similar.
The magnitude of dark opening of stomata on leaves of Irish potato (Solanum tuberosum L.) was studied to determine if this opening was related to the high sensitivity of these plants to air pollutants. Stomatal opening was studied over diurnal periods both in the field and in controlled environments. In both environments, stomatal conductance decreased rapidly at the initiation of dark to 0.1 cm·s-1 but then increased to 0.2 cm·s-1 over the dark period. However conductance was always less in the dark than in the light (0.3 to 0.9 cm·s-1). During the early part of the dark period, stomatal conductance in controlled environments was not as great as in the field, but conductance was similar in both environments over the latter part of the dark period. Cultivars Norchip and Kennebec had smaller conductances during the first hours of the dark than Haig or Katahdin, and all cultivars increased in conductance over the dark period. `Haig' showed slightly higher conductance than the other three during the last 4 hours of the dark period. Injury to `Haig' from 3-hour fumigations with sulfur dioxide (SO2) or ozone (O3) demonstrated that exposures during the day generally produced more injury than during the night, although exposures with SO2 during the last 3 hours of the light period produced similar injury to exposures at the end of the dark period. Thus, although partial opening during the dark may be permitting some pollution injury, it is concluded that previous published reports of similar opening of stomata on Irish potatoes during the light and dark periods, and equal or greater pollution injury during the dark compared with the light period, were not substantiated and apparently resulted from procedural artifacts.
dioxide is commonly added to the juice before and after fermentation. Increased concentrations of molecular sulfur dioxide have been demonstrated to contribute to pathogen inactivation in wine and in sweet (unfermented) cider in some cases ( Basaran