Ida A. Leone

Effect of nitrogen nutrition on the response of tobacco to ozone in the atmosphere

With Nicotiana rustica L., a noncommercial tobacco, plants receiving an optimum nitrogen supply were found to be more susceptible to ozone injury than those receiving deficient or luxury supplies. Furthermore, it was found on analyses of the third oldest tobacco leaf that, while these optimum plants showed little or no increase in respiration as a result of ozone in concentrations too low to produce visible injury, plants grown with deficient or excess nitrogen showed a significant increase in respiration under these same conditions. The increase in respiration was accompanied by a comparable and equally significant decrease in carbohydrate content in the latter plants which was not apparent in plants at the optimum nitrogen supply, as well as an increase in total nitrogen, protein-nitrogen, and amino-acid nitrogen. It is suggested that the carbohydrate reserve built up in plants grown with deficient nitrogen nutrition serves as protection against the oxidative potential of ozone. Likewise, a decrease in carbohydrate content below that of optimum plants provides protection in plants grown with an overabundance of nitrogen fertilization, though possibly by a more complex mechanism. 20 references, 7 figures, 2 tables.

Modification of Sulfur Dioxide Injury to Tobacco and Tomato by Varying Nitrogen and Sulfur Nutrition

The body of information presented in this paper is directed to plant scientists who are concerned with factors which modify the susceptibility of plants to air pollutants. Tobacco and tomato plants grown in sand-solution culture with varying levels of nitrogen or sulfur were exposed to injurious levels of sulfur dioxide. Plants of both species which were deficient in either nutrient exhibited decreased susceptibility to the gas compared with plants grown at optimal levels of each nutrient. Foliage of these plants was also found to have increased stomatal resistance as measured by a porometer and decreased total sulfur accumulations. Plants grown at optimum levels of each nutrient showed increased susceptibility over that of the deficient plants. Stomatal resistance was lower and sulfur accumulation was greater than in the deficient plants. At the supra-optimal nitrogen and sulfur levels, there were differences in susceptibility. Over-abundant nitrogen appeared to decrease susceptibility whereas over-suppl...

Sulfur nutrition as it contributes to the susceptibility of tobacco and tomato to SO2 injury

Abstract Tobacco and tomato plants grown at varied sulfur levels were exposed to phytotoxic concentrations of atmospheric sulfur dioxide (SO 2 ). Increased sulfur nutrition was associated with a greater degree of SO 2 susceptibility in both species. The increased injury parallelled elevated foliar total-sulfur absorption from both the nutrient solution and the SO 2 -atmosphere.

Interaction of Tobacco Mosaic Virus and Ozone in Nicotiana sylvestris

The relationship between a pollutant and a diseased plant was examined in this work. The response of virus-free and virus-infected tobacco plants to ozone was compared, and the effect of ozonation on the production of active virus in the plant tissue was considered. Ozonation did not produce the changes in the virus-infected tissue that it did in the virus-free tissue. The test indicated an increase in Tobacco mosaic virus activity in ozonated tobacco foliage. Apparently there is a time-dependent stimulating action of ozone on virus activity. 5 references.

The importance of moisture in ozone phytotoxicity

Abstract A study was conducted to determine the effect of controlled levels of humidity and/ or free moisture on ozone toxicity to several plant species. The results indicated that increasing relative humidity caused a corresponding increase in plant injury when ozone concentration was not limiting. Similarly, the presence of free moisture on plant foliage caused toxicity when ozone concentration and relative humidity were not limiting.

The relationship of wind parameters in determining oxidant concentrations in two New Jersey communities

Abstract A 2-year study of the relationship of wind speed and direction to total oxidant (including ozone) concentration and phytotoxicity was made of two New Jersey communities, Carlstadt and New Brunswick, where air pollution damage to vegetation has frequently been observed. Results obtained during a 4-hr period from 11.00 to 15.00 local time indicated a negative correlation between wind speed and oxidant concentration which was significant (at P = 0.05) during all months of the year. Winds originating from the directions of heavily populated and industrialized areas with respect to each community were associated with oxidant concentrations which were significantly higher than those occurring when winds proceeded from suburban or residential areas. While wind speed was not demonstrated to be related to the build-up of the very low concentrations required to injure extremely sensitive tobacco plants (0.035 ppm), higher concentrations (above 0.060 ppm) correlated very well with changes in wind speed. Whereas 46 per cent of all the oxidant concentrations in excess of 0.035 ppm occurred when the wind was less than 4 m.p.h. in velocity, 90 per cent of the concentrations above 0.060 ppm occurred when wind speed was at this low level. As with earlier results for sulfur dioxide concentrations, the majority of potentially phytotoxic oxidant concentrations in Carlstadt or those which could be injurious to sensitive crops if grown in the area were associated with the winds originating from the NE and SW. Concentrations at this level rarely occurred when the wind was from due N.

A Bioassay for Assessing the Effect of Sulfur Dioxide on Oat Seedlings

A bioassay technique was developed to evaluate the effect of sulfur dioxide air pollution on the growth rates of oat seedlings. The system was designed to measure small changes in shoot length of seedlings in vivo by use of a millimeter rule. The data, subjected to appropriate statistical evaluation, lead to the conclusion that oat seedlings experienced subtle injury in the form of growth retardation during exposure to SO/sub 2/ at concentrations close to ambient levels. Recovery of the seedlings was relatively rapid and indirectly proportional to SO/sub 2/ concentration. However, recovery generally did not reach the rate of growth that existed prior to fumigation, indicating the possibility of permanent growth impairment or that the stationary phase of growth was being approached. Knowledge of subtle injury of vegetation as seen in this study could possibly lead to in vivo systems for the direct evaluation of air pollution effects on vegetation, help to expand knowledge in the areas of economic loss, or possibly aid in the selection of tolerant species as buffer zones in land use planning.