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  • 1
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The impact of elevated ultraviolet-B radiation (UV-B, 280–320 nm) on membrane systems and lipid peroxidation, and possible involvement of active oxygen radicals was investigated in leaves of two UV-B susceptible rice cultivars (Oryza sativa L. cvs IR74 and Dular). Rice seedlings were grown in a greenhouse for 10 days and then treated with biologically effective UV-B (UV-BBE) radiation for 28 days. Oxidative stress effects were evaluated by measuring superoxide anion (O2) generation rate, hydrogen peroxide (H2O2) content, malondialdehyde (MDA) concentration and relative electrolyte conductivity (EC) for IR74 and Dular at 0 (control), 6 or 13 kJ m−2 day−1 UV-BBE. Significant increases in these parameters were found in rice plants grown at 13 vs 0 kJ m−2 day−1 UV-BBE after 28 days; indicating that disruption of membrane systems may be an eventual reason for UV-B-induced injury in rice plants. There was a positive correlation between O2− generation and increases in EC or MDA in leaves. Activities of enzymatic and nonenzymatic free radical scavengers were measured for IR74 after 7, 14, 21 and 28 days of exposure to 13 or 0 UV-BBE to evaluate dynamics of these responses over time. Activities of catalase and superoxide dismutase (but not ascorbate peroxidase) and concentrations of ascorbic acid and glutathione were enhanced by 13 vs 0 UV-BBE after 14 days of UV-B exposure. Further exposure to 28 days of UV-B was associated with a decline in enzyme activities and ascorbic acid, but not glutathione. It is suggested that UV-B-induced injury may be associated with disturbance of active oxygen metabolism through the destruction and alteration of both enzymatic and nonenzymatic defense systems in rice.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1435-0653
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Turf quality declines in creeping bentgrass (Agrostis palustris Huds.) with increasing temperatures and decreasing soil aeration. This experiment examined how root activities of 'Crenshaw' and 'Penncross' were affected by high temperature and low soil aeration. Turfgrass was maintained in growth chambers at day/night temperatures of 22/15°C (optimum) or 35/25°C (high temperature, HT). Aeration treatments were: (i) adequate aeration by maintaining soil medium well-drained; (ii) low aeration (LA) induced by maintaining soil medium saturated with water. Shoot dry matter production (SDM) declined with HT + LA at 7 days of treatment (DOT) in Penncross, and at 21 and 35 DOT with HT, LA, and HT + LA for both cultivars. Reduced root dry mass was measured at 7 DOT under HT + LA, and at 21 and 35 DOT under HT, LA, or HT + LA for both cultivars. Root viability was lower after 7 DOT and 21 DOT of HT, LA, and HT + LA. Viability was reduced more in Penncross than in Crenshaw after 21 DOT with HT + LA, and 35 DOT with HT and HT + LA. Root porosity increased with LA and HT + LA, beginning 7 DOT for both cultivars, to a greater extent in Crenshaw after 21 and 35 DOT with HT + LA. The combination of HT and LA had more severe effects on viability than either HT or LA alone. Results suggest that reduction in root growth, and particularly root viability, under HT and LA could contribute to the declines and cultivar variations in bentgrass quality.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Crop science 40 (2000), S. 503-510 
    ISSN: 1435-0653
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Agrostis palustris Huds.) . Two creeping bentgrass cultivars differing in heat tolerance, L-93 (heat tolerant) and Penncross (heat sensitive) were grown under two temperature regimes: 22/16°C (day/night) and 35/25°C for 56 d in growth chambers. Photochemical efficiency (Fv/Fm) and chlorophyll content of leaves; and electrolyte leakage (EL); content of the lipid peroxidation product, malondialdehyde (MDA); and activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) in leaves and roots were determined biweekly during heat stress. Leaf Fv/Fm ratio and chlorophyll content decreased, whereas EL and MDA contents of both leaves and roots increased under heat stress in both cultivars, but to a greater extent in Penncross. The activities of SOD and CAT decreased, whereas POD activity increased in both leaves and roots, which occurred to a greater extent for Penncross. The increases in MDA content and POD activity under heat stress were greater for leaves than for roots in both cultivars. These results suggest that decreased activities of antioxidant enzymes could result in an increased level of lipid peroxidation. Thus, decreased activities of antioxidant enzymes could contribute to damage of cell membranes and to leaf senescence as demonstrated by increased EL and reduced Fv/Fm, and by decreased chlorophyll content during heat stress. Cultivar variations in antioxidant enzyme activities were associated with their differences in heat tolerance as evidenced by Fv/Fm ratio, chlorophyll content, and EL.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1435-0653
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Agrostis palustris Huds.) will help management and breeding programs to improve summer turf quality. The objective of this study was designed to examine shoot physiological responses of 'Crenshaw' and 'Penncross' to high temperature and poor soil aeration. Turf was maintained in growth chambers at day/night temperatures of 22/15°C (optimum) or 35/25°C (high temperature, HT). Soil aeration treatments were (i) adequate aeration with oxygen diffusion rate (ODR) at 1.5 μg cm-2 min-1 by maintaining the soil medium well watered and well drained and (ii) low aeration (LA) with ODR below 0.2 μg cm-2 min-1 induced by flooding the soil medium. Turf growth, quality, chlorophyll content (Chl), and net photosynthetic rate (Pn) declined with increasing temperatures or declining aeration for both Crenshaw and Penncross. The HT treatment increased canopy minus air temperatures (δT) and dark respiration rates (Rn) for both cultivars, with a greater rise in Rn for Penncross (44%) than for Crenshaw (25%). The LA treatment inhibited Rn but had no effect on δT. The combination of HT and LA had more severe adverse effects than either HT or LA alone on turf quality, leaf chlorophyll content, photosynthesis and respiration, particularly for Penncross. The results demonstrated genetic variations in shoot physiological responses to high temperature and poor soil aeration stresses in creeping bentgrass and indicated that high temperature, when combined with poor soil aeration lead to turf quality decline. This was mainly due to reduced net photosynthesis and increased respiration rates.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-5036
    Keywords: activated oxygen ; activated oxygen scavenging system ; flooding ; lipid peroxidation ; membrane injury ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Flooding effects on membrane permeability, lipid peroxidation and activated oxygen metabolism in corn (Zea mays L.) leaves were investigated to determine if activated oxygens are involved in corn flooding-injury. Potted corn plants were flooded at the 4-leaf stage in a controlled environment. A 7-day flooding treatment resulted in a significant increase in chlorophyll breakdown, lipid peroxidation (malondialdehye content), membrane permeability, and the production of superoxide (O 2 - ) and hydrogen peroxide (H2O2) in corn leaves. The effects were much greater in older leaves than in younger ones. Spraying leaves with 8-hydroxyquinoline (an O 2 - scavenger) and sodium benzoate (an .OH scavenger) reduced the oxidative damage and enhanced superoxide dismutase (SOD) activity. A short duration flooding treatment elevated the activities of SOD, catalase, ascorbate peroxidase (AP), and glutathione reductase (GR), while further flooding significantly reduced the enzyme activities but enhanced the concentrations of ascorbic acid and reduced form glutathione (GSH). It was noted that the decline in SOD activity was greater than that in H2O2 scavengers (AP and GR). The results suggested that O 2 - induced lipid peroxidation and membrane damage, and that excessive accumulation of O 2 - is due to the reduced activity of SOD under flooding stress.
    Type of Medium: Electronic Resource
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