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Biomedical subjects

W A Feder

Publications and source records attributed to W A Feder.

6 recordsLinked to original sources
PubMed1987

Growth and disease response of soybeans from early maturity groups to ozone and Fusarium oxysporum.

The single and combined effects of ozone (O(3)) and Fusarium oxysporum on growth and disease expression of soybean genotypes differing in foliar sensitivity to O(3) were studied in the greenhouse. O(3) had no effect on root and hypocotyl rot severity of PI 153.283 (O(3)-sensitive, S) or PI 189.907 (O(3)-tolerant, T) maturity group I soybean lines. Plants of both genotypes infected with F. oxysporum and exposed to O(3) had greater reductions in relative growth rate (RGR), net assimilation rate (NAR), and had more stippled leaves per plant than Fusarium-free plants exposed to O(3). O(3) alone had a greater impact on shoot dry weight, RGR, and NAR of PI 153.283 (S) than of PI 189.907 (T). O(3) alone reduced shoot and root dry weights primarily through a depression in NAR and less through reduced leaf area. F. oxysporum alone reduced root dry weight at 35 days; however, infected plants responded with increases in root dry weight from 49 to 63 days. Similarly, F. oxysporum alone lowered early RGR but subsequent RGR decline was less rapid while NAR remained high, particularly during later sampling intervals. Infection by F. oxysporum that causes root and hypocotyl rot increased soybean sensitivity to O(3) by prolonging active vegetative growth.

Journal Article↗
PubMed1981

Bioassaying for ozone with pollen systems.

Sensitivity to ozone of pollen germinating in vitro is closely correlated with ozone sensitivity of the pollen parent. Ozone-sensitive and tolerant pollen populations have been identified in tobacco, petunia, and tomato cultivars. The rate of tube elongation can be reversibly slowed or stopped by exposure to low concentrations of ozone. Tube growth rates in the presence of a range of ozone dosages, of pollen populations exhibiting differing ozone sensitivity can be measured and different growth rates can be correlated with ozone dosages. The performance of selected pollen populations can then be used to bioassay ozone in ambient air by introducing the air sample into a growth chamber where ozone-sensitive pollen in growing. Petunia and tobacco pollen are especially useful because they store well at ordinary freezer temperatures and do not require special preparation prior to storage. Modified Brewbacker's growth medium is suitable for growth of both these pollen types. Four useful cultivars are Bel W-3, ozone-sensitive and Bel B, ozone-tolerant tobacco, and White Bountiful, ozone-sensitive and Blue Lagoon, ozone-tolerant petunia. Observations can be made directly by using a TV scanner, or by time lapse or interval photography. Year-round pollen production can be achieved in the greenhouse. Harvested pollen can be tested, packaged, and transported to user facilities without loss of vigor. Pollen populations are inexpensive to produce, respond reliably, and are simple to use as a bioassay for air quality.

Biological Assay↗
PubMed1978

Plants as bioassay systems for monitoring atmospheric pollutants.

Plant species act as natural bioindicators of atmospheric pollutants. Plants can be used as bioassay systems for monitoring atmospheric pollutants. Plant injury symptoms, altered growth and reproductive pattern, changes in yield and/or productivity, and changes in species distribution can be used singly or in combination as monitoring devices. The results must be accepted as semiquantitative, but within that constraint, air quality can be sufficiently well defined to enable the setting of air quality standards. Genetic variability of higher plant species has yielded cultivars which display a range of tolerance to gaseous and particulate atmospheric pollutants. Asexual propagation of these cultivars provides pollutant-sensitive and pollutant-tolerant plant material which can be grown on selected sites for observation. Gymnosperm and Angiosperm species as well as species of lichens and mosses have been used to establish field monitoring networks in Europe, Canada, and the United States. White pine, shade tobacco, mosses, and lichens have proven particularly useful as bioassay tools. Pollen from pollutant-sensitive and pollutant-tolerant plant cultivars has also been used as a sensitive laboratory bioassay tool for studying air quality. Epiphytic mosses are particularly efficient as monitors of particulate pollutants, especially heavy metals, some of which may act as chemical mutagens. The cost, complexity, and lack of reliability of instrumented systems for air quality monitoring make imperative the need to develop successful plant bioassay systems for monitoring air quality.

Air Pollutants↗
PubMed1969

Ozone: depression of frond multiplication and floral production in duckweed.

Plants of Lemna perpusilla #6746 grown in an environment charged daily with a low concentration of ozone over 2 weeks were slower to begin multiplying, had a significantly lower rate of frond doubling, and required longer to produce fewer flowers than control plants. Treated plants produced smaller, slightly yellow fronds but had no symptoms of acute injury. Control plants produced four times as many fronds and six times as many flowers as plants continuously exposed to ozone (0.1 part per million).

Air Pollution↗
PubMed1968

Reduction in tobacco pollen germination and tube elongation, induced by low levels of ozone.

Pollen of the ozone-sensitive tobacco variety Bel W-3 undergoes a reduction in germination rate and tube elongation when exposed to ozone. As little as 0.1 part of ozone per million for a 5.5-hour exposure period is sufficient to cause a 40 to 50 percent reduction in germination and a 50 percent reduction in pollen-tube elongation. Ozone causes these effects to approximately the same degree whether the pollen is exposed to ozone in vitro or agar disks, or in vivo when the intact plant is exposed. Exposure to ozone at a concentration of 1.0 part per million for more than 3 hours in vitro completely prevents germination of Bel W-3 pollen.

Air Pollution↗