The effects of calcium (Ca2+) supplementation on the freezing resistance of white poplar (Populus... more The effects of calcium (Ca2+) supplementation on the freezing resistance of white poplar (Populus alba, frost hardy) and hornbeam (Carpinus betulus, frost sensitive) were studied by monitoring alterations in leaf fatty acids, chlorophyll fluorescence emissions, necrosis, mortality, and growth. Calcium supplementation had no significant effect on leaf fatty acids before, and from weeks 2 through 8 after, freezing. Percentages of the saturated fatty acid C16 were significantly higher in Caz+-supplemented plants immediately following freezing (day 1) only. In P. alba, leaf chlorophyll fluorescence and necrosis values were significantly higher and lower than in controls immediately after freezing; readings from weeks 2 through 8 did not significantly differ from controls. Leaf chlorophyll fluorescence and necrosis values in C. betulus after freezing were significantly higher and lower than in controls throughout the experiment. Calcium concentrations were significantly higher in supplem...
The efficacy of different fungal and chemical elicitors of systemic protection and their effects ... more The efficacy of different fungal and chemical elicitors of systemic protection and their effects on plant growth and development were examined in barley (Hordeum vulgare) and broad bean (Vicia faba). Powdery mildew (Blumeria graminis syn. Erysiphe graminis f sp. hordei) of barley and rust (Uromyces viciae fabae) of broad bean, two biotrophic pathogens, were used as fungal elicitors to induce systemic protection in barley and bean respectively, and the upper leaves of plants were subsequently challenged with the same pathogens. Powdery mildew applied to the lower leaves of barley was found to induce systemic protection against powdery mildew in upper leaves. However, whole plant fresh and dry weight, and total leaf area was approximately 50% lower in barley 14 d after inoculation of the first leaves with mildew. The total number of leaves and tillers were also reduced by approximately 30%. Consequently, although there was a reduction in total infection in the mildew treated plants th...
Treatment of barley (Hordeum vulgare) with 3 mm saccharin, applied as a foliar treatment to the f... more Treatment of barley (Hordeum vulgare) with 3 mm saccharin, applied as a foliar treatment to the first leaf or as a soil drench, provided significant control of powdery mildew (Blumeria graminis f.sp. hordei) on first and second leaves. This was unlikely to be the result of a direct effect of saccharin on the fungus, as application of the chemical to first leaves 2 h before inoculation did not affect conidial germination or formation of appressoria. Saccharin treatment had no significant effect on plant growth, except for a reduction in total leaf area in plants treated with a saccharin drench 14 days before inoculation with mildew. Phenylalanine ammonia‐lyase activity was reduced significantly in second leaves 18 and 48 h after inoculation in plants treated with saccharin 14 days earlier. Peroxidase activity increased significantly in plants challenged with mildew within 6 days of saccharin application, although changes were not apparent until 48 h after pathogen challenge. On these...
Here, we examine the effect of saccharin on the induction of systemic resistance in broad bean (V... more Here, we examine the effect of saccharin on the induction of systemic resistance in broad bean (Vicia faba) to the rust fungus Uromyces viciae-fabae. Saccharin was applied to beans at the three-leaf stage, either as a soil drench or by painting the solution on to first leaves. Plants were then challenge inoculated with the rust 1, 6, 10 and 14 d following saccharin treatment, after which they were harvested, assessed for the intensity of rust infection and plant growth measurements conducted. Foliar application of saccharin did not induce systemic protection to rust infection until 14 d after application and was less effective than saccharin applied as a soil drench. When saccharin was applied as a drench, systemic protection was not observed until 6 d after application, but was still apparent in plants 14 d after application of the drench. Irrespective of the method of application, saccharin had no significant effect on fresh and dry weights or leaf area of the plants. Saccharin applied as a drench did, however, reduce the number of leaflets produced.
The effects of calcium (Ca2+) supplementation on the freezing resistance of white poplar (Populus... more The effects of calcium (Ca2+) supplementation on the freezing resistance of white poplar (Populus alba, frost hardy) and hornbeam (Carpinus betulus, frost sensitive) were studied by monitoring alterations in leaf fatty acids, chlorophyll fluorescence emissions, necrosis, mortality, and growth. Calcium supplementation had no significant effect on leaf fatty acids before, and from weeks 2 through 8 after, freezing. Percentages of the saturated fatty acid C16 were significantly higher in Caz+-supplemented plants immediately following freezing (day 1) only. In P. alba, leaf chlorophyll fluorescence and necrosis values were significantly higher and lower than in controls immediately after freezing; readings from weeks 2 through 8 did not significantly differ from controls. Leaf chlorophyll fluorescence and necrosis values in C. betulus after freezing were significantly higher and lower than in controls throughout the experiment. Calcium concentrations were significantly higher in supplem...
The efficacy of different fungal and chemical elicitors of systemic protection and their effects ... more The efficacy of different fungal and chemical elicitors of systemic protection and their effects on plant growth and development were examined in barley (Hordeum vulgare) and broad bean (Vicia faba). Powdery mildew (Blumeria graminis syn. Erysiphe graminis f sp. hordei) of barley and rust (Uromyces viciae fabae) of broad bean, two biotrophic pathogens, were used as fungal elicitors to induce systemic protection in barley and bean respectively, and the upper leaves of plants were subsequently challenged with the same pathogens. Powdery mildew applied to the lower leaves of barley was found to induce systemic protection against powdery mildew in upper leaves. However, whole plant fresh and dry weight, and total leaf area was approximately 50% lower in barley 14 d after inoculation of the first leaves with mildew. The total number of leaves and tillers were also reduced by approximately 30%. Consequently, although there was a reduction in total infection in the mildew treated plants th...
Treatment of barley (Hordeum vulgare) with 3 mm saccharin, applied as a foliar treatment to the f... more Treatment of barley (Hordeum vulgare) with 3 mm saccharin, applied as a foliar treatment to the first leaf or as a soil drench, provided significant control of powdery mildew (Blumeria graminis f.sp. hordei) on first and second leaves. This was unlikely to be the result of a direct effect of saccharin on the fungus, as application of the chemical to first leaves 2 h before inoculation did not affect conidial germination or formation of appressoria. Saccharin treatment had no significant effect on plant growth, except for a reduction in total leaf area in plants treated with a saccharin drench 14 days before inoculation with mildew. Phenylalanine ammonia‐lyase activity was reduced significantly in second leaves 18 and 48 h after inoculation in plants treated with saccharin 14 days earlier. Peroxidase activity increased significantly in plants challenged with mildew within 6 days of saccharin application, although changes were not apparent until 48 h after pathogen challenge. On these...
Here, we examine the effect of saccharin on the induction of systemic resistance in broad bean (V... more Here, we examine the effect of saccharin on the induction of systemic resistance in broad bean (Vicia faba) to the rust fungus Uromyces viciae-fabae. Saccharin was applied to beans at the three-leaf stage, either as a soil drench or by painting the solution on to first leaves. Plants were then challenge inoculated with the rust 1, 6, 10 and 14 d following saccharin treatment, after which they were harvested, assessed for the intensity of rust infection and plant growth measurements conducted. Foliar application of saccharin did not induce systemic protection to rust infection until 14 d after application and was less effective than saccharin applied as a soil drench. When saccharin was applied as a drench, systemic protection was not observed until 6 d after application, but was still apparent in plants 14 d after application of the drench. Irrespective of the method of application, saccharin had no significant effect on fresh and dry weights or leaf area of the plants. Saccharin applied as a drench did, however, reduce the number of leaflets produced.
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