Search Results
Abstract
Effects of day/night temperatures of 28°/16° and 28°/8°C, low and high water stress in the rooting medium, and several ammonium and nitrate sources on apparent ammonium toxicity in plants of ‘Honey Gold’ and ‘Spring Green’ snap beans (Phaseolus vulgaris L.) were evaluated in controlled environments. Apparent ammonium toxicity, in terms of visible injury and reduced plant height and weight, was generally accentuated by high water stress prior to application and to a lesser extent by cooler night temperature. ‘Spring Green’ was more sensitive than ‘Honey Gold’ to apparent ammonium injury. At equimolar concentrations, added (NH4)2SO4 was generally more injurious than added NH4NO3.
Abstract
Worldwide industrialization and urbanization are resulting in modifications of the atmosphere in which horticultural plants must be produced. CO2 concentration is increasing steadily as fossil fuels are burned and emissions of industrial pollutants are also increasing, in part because lower quality fuels are being used as energy sources. Burning of fossil fuels, particularly low-quality coal, produces emissions of sulfur and nitrogen oxides. These gaseous pollutants and others resulting directly from industrial processing may have direct and indirect effects on horticultural crops. For example, there is now an acute awareness that acid precipitation originating in industrial emissions may have severe ecological effects and that worldwide political interactions may be involved.
Abstract
Dikegulac-sodium application markedly increased branch number and decreased branch length of Forsythia × intermedia Zab. plants, but salt application to the rooting medium decreased the effectiveness of this growth retardant. Ancymidol reduced branch length without increasing branch number, while daminozide did not affect branch length or number. Salt application did not affect plant response to ancymidol or daminozide.
Abstract
Polyamines acted as antisenescence agents (2, 5), increased membrane stability of beet root, rose petal, and spinach leaf tissue (8, 9), and decreased the rate of chlorophyll degradation in radish cotyledons (2). Ozone is a major air pollutant causing economic losses to crops in agricultural areas (1). One approach to controlling the damage caused by ozone has been the use of chemical protectants (7), but consistent responses have been difficult to achieve. The antisenescence properties of polyamines may confer protectant properties that will reduce or prevent ozone-induced injury to plants. Previous studies have shown increased membrane permeability by ozone at 0.15 μl·liter−1 (4) and increased senescence with ozone at 0.15 μl·liter−1 (3). The objective of this study was to determine if the polyamines—spermine, spermidine, and putrescine—could act as protectants in tomato (Lycopersicon esculentum Mill.).
Abstract
Observation of vegetation injury induced by exposure to air pollutants provides a simple and low cost means of monitoring pollutant emissions from a particular source as well as for determining the distribution of pollutants over a wide area. This use of plants has long been accepted and has been extensively reported (2, 7, 8, 14). However, many other environmental factors may also cause plant injury and their effects are often difficult to distinguish from pollution-induced damage (13). In addition, factors such as temperature, humidity, wind velocity, light, nutrition, water supply, and the presence of pesticides and other chemicals have all been shown to markedly influence plant sensitivity to air pollutants.
Abstract
Potato plants (Solanum tuberosum L.) were propagated in controlled environments from tubers or stem cuttings and exposed to SO2 and/or NO2. Cultivar, propagation method, and air quality affected intumescence formation on leaves. Tuber-propagated ‘Kennebec’ and ‘Russet Burbank’ plants developed intumescences in clean air, SO2, or NO2, but not in a SO2-NO2 mixture, whereas tuber-propagated ‘Superior’ and ‘Norchip’ had little or no intumescence formation. Cutting-propagated ‘Kennebec’, ‘Russet Burbank’, and ‘Norchip’ plants had no intumescence development. Intumescence development may be related to carbohydrate status of plants and maturity classification of cultivars.
Abstract
Eighteen cultivars representing 6 species (Poa pratensis L., Agrostis alba L., Agrostis palustris Huds., Agrostis tenuis Sibth., Festuca rubra Gaud., and Lolium perenne L.) of cool season turfgrass were exposed to 15 pphm ozone for 6 hours daily, 15 pphm sulfur dioxide continuously, 15 pphm nitrogen dioxide continuously, or a mixture of all three at these concentrations for 10 days. The most common symptoms of injury on sensitive cultivars in response to these gases were bleaching and necrosis of leaves with some cultivars exhibiting dark brown necrosis and stippling in response to O3 alone. Cultivars varied in sensitivity to O3 or SO2 from very sensitive to insensitive while few cultivars were sensitive to NO2 alone at the concentration used. Exposure of some cultivars resulted in less leaf area production but no visible injury symptoms, while other cultivars had leaf injury without reduction of area of uninjured leaves. The combined exposure caused more leaf injury and greater reduction in the leaf area production by most cultivars compared with plants exposed to single gases. Exposure to single pollutants could provide inaccurate estimates of turfgrass cultivar sensitivity outdoors where several pollutants may occur simultaneously.
Abstract
The systemic fungicides benomyl and carboxin were evaluated in controlled environment chambers as ozone protectants on annual bluegrass (Poa annua L.), Kentucky bluegrass (Poa pratensis L. cv. Merion) and creeping bentgrass (Agrostis palustris Huds. cv. Penncross); and in open-top outdoor chambers on creeping bent-grass. Benomyl sprays were effective in reducing ozone-induced injury in controlled environments on all grasses at all rates used. Carboxin was not a satisfactory ozone protectant and had direct toxic effects on leaves of all 3 species. Growth retardation due to ozone or carboxin was generally proportional to leaf injury. Benomyl sprays in the outdoor situation limited ozone injury on creeping bentgrass for several weeks in the summer but for a much shorter time in the fall.
Abstract
Plants of 8 cultivars of eggplant (Solanum melongena L.) exposed to 0 to 40 pphm ozone for 6 hr each day at 35 and 36 days of age varied in susceptibility as indicated by leaf area damage. The most sensitive cultivar was ‘Early Hybrid’; least sensitive was ‘Blacknite’.
Abstract
Plants of 8 cultivars of celery (Apium graveolens L. var. dulce) exposed to ozone under controlled conditions, or grown in the field under ambient conditions, had comparable injury symptoms but varied in relative susceptibility to injury in the 2 different environments.