Jay S. Jacobson

The Accumulation of Fluorine by Plants

The accumulation and distribution of fluorine (F) in -plant leaves have been studied to better understand the response of plants to concentrations of atmospheric fluoride (F) that are similar to those found in urban or industrial areas. The results indicate that F from the air can be adsorbed to the surface of leaves as well as accumulated internally and that F in leaves can be translocated outward to the surface as well as upward to the tips. F injury and accumulation can be induced in any desired location on a gladiolus blade by restricting gas exchange of the blade, indicating that all parts of a blade are sensitive to F-induced injury. It is, therefore, suggested that the wide differences often found between plant species and varieties with respect to both susceptibility to injury and degree of F accumulation may be explained by differences in the means of accumulation, trans-location, and distribution of F. F remains in a soluble form in plant leaves and maintains the chemical properties of free, ino...

Effects of acidity of simulated rain and its joint action with ambient ozone on measures of biomass and yield in soybean

Abstract An experiment was performed to determine whether the presence of ozone modified the effects of acidity of simulated rain on growth and yield of soybean ( Glycine max. [L.] Merr.). Beeson, a type II cultivar, was grown in field chambers and exposed to simulated rain at 3 levels of acidity, pH 4.0, 3.4 and 2.8. Each level of acidity was applied to plants grown either in unfiltered ambient air or in charcoal filtered (to remove ozone) ambient air. An interaction between acidity of simulated rain and filtration of ambient air on growth and yield was present. The difference in total dry mass between plants grown in filtered and unfiltered chambers increased with increased acidity, of simulated rain treatments. In filtered air, vegetative mass was only slightly decreased with increased acidity, whereas reproductive mass was increased with increased acidity. In unfiltered air vegetative mass decreased with increased acidity but reproductive mass was only slightly decreased at pH 2.8. Components of yield also were differentially affected by acidity, which indicates the need for a better understanding of the sensitivities of different development processes of the plant to each kind of pollutant. The apparent interaction between ozone and acidic rain indicates that further investigations on this combination must be conducted before acidic rain effects on plant growth can be accurately assessed in ambient atmospheres.

CHANGES IN FOLIAR ELEMENTS IN RED SPRUCE SEEDLINGS AFTER EXPOSURE TO SULFURIC AND NITRIC ACID MIST

Red spruce (Picea rubens Sarg.) seedlings were exposed repeatedly at a field site or in a greenhouse to acidic mist containing the major sulfur and nitrogen pollutants of wet deposition in the eastern U.S.: sulfate alone, nitrate alone or with ammonium ion, and a combination of these ions. Acidities and ion concentrations ranged from below the mean to above the maximum concentration for cloudwater in the eastern U.S. Effects on elements in current-year foliage were examined after continuous or intermittent overnight exposures to mist performed over periods of 6 to 19 weeks. Principal findings from five experiments conducted over a three-year period were that acidic mist 1) increased the foliar S and/or N content when exposures were intermittent with repeated opportunities for drying of liquid on foliage; 2) decreased foliar calcium, and/or magnesium content, especially when exposures to acidic mist were continuous rather than intermittent; and 3) gave inconsistent results for foliar iron and aluminum probably because of deposition of soil particles and contamination with metals from the mist delivery system. These results indicate that long-duration exposures to cloudwater with pH below 3 may alter foliar nutrient composition and change relationships between N, S, Ca, and Mg, with potential consequences for growth and resistance to natural stress factors.

The combined effect of sulfur dioxide and ozone on bean and tobacco plants

Abstract Plants of two cultivars of Phaseolus vulgaris L. and one cultivar of Nicotiana tabacum L. were exposed to a replicated series of concentrations of sulfur dioxide (SO 2 ), ozone (O 3 ), and combinations of these two air pollutants for single four-hour periods. Experiments were performed in controlled-environment chambers using concentrations of pollutants above and below Federal ambient air quality standards in order to determine whether interactive effects result from exposure to concentrations of pollutants occurring in some agricultural areas of the United States. Dose-response curves for foliar symptoms were found to approximate logarithmic functions of pollutant concentrations when the frequency of leaf injury was converted into probit units. In bean cultivars, the toxicity of SO 2 or O 3 was either attenuated or not affected when the two pollutants were combined depending on their concentrations. In tobacco, the toxicity of SO 2 or O 3 was either amplified or not affected in the presence of the two pollutants. Concentrations of SO 2 or O 3 that did not exceed the respective U.S. ambient air quality standards significantly altered the incidence of injury caused by the other pollutants. These results demonstrate that interactive effects between SO 2 and O 3 can occur but the magnitude and direction of these effects depend on plant species and concentrations of pollutants.

SOME EFFECTS OF ATMOSPHERIC FLUORIDE ON PLANT METABOLISM.

Leaves of Tendergreen bean plants exposed to atmospheric fluoride concentrations in the range 1.7 to 7.6 μg/m3 showed increased levels of enolase and catalase activity and decreased levels of pyruvate and α-ketoglutarate. Phosphoenolpyruvate carboxylase activity and oxalacetate were not affected. The leaves of Milo maize plants exposed to 5.0 μg F/m3 showed increased levels of enolase and pyruvate kinase activity and a decreased level of pyruvate. Oxalacetate and α-ketoglutarate levels were not affected. Catalase activity was increased, then decreased by IIF fumigation. The changes induced by HF were greatest six to 10 days after the start of fumigation and disappeared or decreased in magnitude during the post-fumigation period.

A Simple, Rapid Potentiometric Method for the Estimation of Fluoride in Vegetation

Abstract A new method for the estimation of fluoride in vegetation has been developed. The technique employs a selective ion electrode for measurement of fluoride obtained by acid extraction from pulverized plant tissue. This potentiometric method is simple and rapid and provides results which correlate with those obtained by established methods.

Studies on the Measurement of Fluoride in Air and Plant Tissues By the Willard-Winter and Semiautomated Methods

Determinations of F in plant tissues by the Willard-Winter and semiautomated methods have been studied for the presence of determinate and indeterminate errors by multiple linear regression analysis. The results have provided a better understanding of the magnitude of differences between tissue samples required for statistical significance and have suggested that the errors involved are much greater both in number and magnitude than usually assumed. The results have also established that the semiautomated method is a satisfactory alternative to the Willard-Winter method for determining the F content of plant tissues. Investigations of the sources of error in F determinations by the semi-automated method were carried out, and the results indicated a number of ways of reducing errors. Determinations of the F content of air by three methods were compared and studied to estimate the magnitude and locate the sources of error. Here, too, the results indicated that present estimates of the reliability of determi...

EFFECTS OF FLUORINE COMPOUNDS ON VEGETATION, WITH SPECIAL REFERENCE TO SWEET CORN.

Since 1951 many fumigation experiments have been carried out with different species and varieties of plants, including field corn and sweet corn. Results for gladiolus and Milo maize have been summarized, but only brief mention has been made of results obtained with corn. This report summarizes some of the earlier results obtained with sweet corn, used alone or in comparative tests with field corn in unreplicated experiments and the results of replicated fumigation experiments with Marcross sweet corn (Zea mays L.) and lambs-quarters (Chenopodium album L.) carried out in 1963.

Phenology and cold tolerance of Picea rubens sarg. Seedlings exposed to sulfuric and nitric acid mist

During the growing seasons of 1985–88, red spruce (Picea rubens Sarg.) seedlings were exposed repeatedly in field chambers to sulfuric and/or nitric acid mist in the range of pH 2.5 to 4.5. Hydrogen ion, sulfate, and nitrate concentrations in mist were within the range found in cloudwater of the northeastern USA where high‐elevation spruce forests are declining. After the period of exposures, seedlings remained outdoors and buds were sampled in the autumn to determine effects of mist treatments on the number of developing needle primordia. Current‐year foliage was sampled from autumn to spring for measurement of cold tolerance by freeze‐induced electrolyte leakage (FIEL) and buds were scored for degree of bud break in the early spring. In the 1985–87 experiments when 16‐hour overnight mist events were continuous, there were few statistically significant effects of acidic mist on needle primodia development, foliar FIEL, and bud‐break. However, in the 1988 experiment when 16‐hour overnight mist events were...

Effects of simulated acidic rain applied alone and in combination with ambient rain on growth and yield of field-grown snap bean

Abstract Field-grown snap bean (Phaseolus vulgaris L. cultivar ‘Provider’) plants were treated with simulated acidic rain applied either alone or in combination with ambient rain and the effects on growth and yield were determined. In plots where ambient rain was excluded, a retractable canopy was activated to shield the crop. Four levels of acidity at pH values of 5.0, 4.2, 3.4 and 2.6 were applied in four replicate treatments and the experiment was conducted in two successive years (1981 and 1982). In plots that received only simulated rain, yield was not adversely affected by acidic rain; in 1981, a positive linear relationship was present between acidity of simulated rain and yield, but in 1982, no effect was found. In contrast, in plots that received both simulated and ambient rain, a negative linear relationship between acidity in simulated rain and yield was observed in both years. Changes in yield were due to effects on the number of pods per plant. Vegetative mass and size of pods were unaffected by acidity in simulated rain in either experimental condition. Apparently, acidic rain has no detrimental effect on growth or yield of snap bean, especially under conditions of normal water supply. Plant response to acidic rain, however, was altered by the presence of ambient rain. Consequently, previous research performed without exclusion of ambient rain should be re-evaluated, and current research should provide for control of water supply as well as deposition of hydrogen ions and other components in rain.