Visible Symptoms Of Damage Research Articles

The role of root system in silver birch (Betula pendula Roth) dieback in the air-polluted area of Krušné hory Mts

120 root systems and trunks of 20 years old birch trees and 60 root systems and trunks of 15 years old birch trees affected by defoliation and with no visual symptoms of damage were analyzed in the air-polluted area of Krušné hory Mts. In the given area, birch develops a superficial or anchoring root system of circular shape. A greater effect of defoliation was recorded in trees with the superficial root system. The defoliation was in correlation with the extent of bole rot, root system rot and rooting depth. The proportion of root system branches infested by rot increased with increasing defoliation. Dominating fungi on roots were Armillaria gallica and Armillaria ostoyae. The degree of defoliation was directly proportional to the extent of bole rot induced by Trametes confragosa and Armillaria gallica, infecting frost ribs in the trunks. Extensive defoliation was recorded if more than 25% of peripheral tissues of the trunk and over 15% of root system branches were infected by rot. The defoliated trees showed a marked loss of fine roots, impaired longevity of fine roots and a change of ectomycorrhiza into ectendomycorrhiza.

CO 2 photoassimilation and chlorophyll fluorescence in two clover species showing different response to O 3

The current study evaluated photosynthetic processes in two clover species based on their performance under high O 3 conditions (150 nl l –1 for 3 h). These species are Trifolium repens L. and Trifolium pratense L., which are well known for their different sensitivity to ozone. Ozone affected the two clover species very differently. In T. pratense, ozone induced visible symptoms of damage even though CO 2 photoassimilation, stomatal conductance and the electron transport rate were not affected. A decrease in the optimal quantum yield was observed in T. pratense immediately after the end of the period of O 3 stress but it reverted to a value similar to the control 24 h after removing the stress, indicating that non-irreversible photoinhibition had occurred. Data obtained for symptomatic T. pratense indicate that still-green living tissue of the leaf is able to carry out CO 2 assimilation; the only parameter found to be affected by O 3 was the efficiency of excitation capture. In T. repens, acute O 3 fumigation induced inhibition of photosynthetic activity, enhanced stomatal closure and increased the reduction state of the PSII primary acceptor. A possible explanation for the inhibition of photosynthesis could reside in inhibition of the Calvin cycle over-reducing PSII, thus increasing (1 – q P) and increasing non-photochemical quenching.

Eficácia de isoxaflutole no controle de plantas daninhas na cultura da batata

This experiment was carried out at Bayer CropScience Experimental Station, in Paulinia, SP, Brazil, in a loamy soil cultivated with potato cv. Monalisa, during the 2002 growing season. The objectives were to evaluate the efficacy of isoxaflutole in weed control, to verify its selectivity to the potato crop and its effect on tubercule yield. The experimental design was a completely randomized block with seven treatments and four replications. The experimental plots consisted offour 7 m rows, with plants spaced in 0.60 m. The treatments were: controls (weedy and weedfree) and isoxaflutole rates (0.075, 0.150 and 0.300 kg/ha). Metribuzin (0.720 kg/ha) and linuron + metribuzin (0.910 + 0.384 kglha) were used as standards. The evaluations of the percentage ofweed control and the selectivity on the potato crop were carried out at 14, 28 and 42 days after treatment adopting a scale in which zero meant no weed control or no crop damage and one hundred corresponded to total control or death of the crop. The main weed species presented in the area were: Digitaria horizontalis Willd., Brachiaria plantaginea (Link.) Hitch, Gali nsoga parviflora Cav., Raphanus raphanistrum L. and Amaranthu s viridis L.. Potato plants did not show any visual symptoms of damage attributed to herbicide treatment. The species weed were efficiently controlled with isoxaflutole but there was no significant difference wheri compared with metribuzin. The treatments with isoxaflutole provided better control than linuron + metribuzin on grasses. Isoxaflutole did not affect the tubercule yield.

Effect of Chronic O<sub>3</sub> Fumigation on the Activity of Some Calvin Cycle Enzymes in Two Poplar Clones

The effects of long-term exposure to ozone (O3, 60 mm3 m-3 for 5 h d-1) on some Calvin cycle enzymes, in particular those modulated by the thioredoxin system, were studied in two poplar clones. These clones differ in sensitivity to O3. In the I-214 clone, the first effects from O3 treatment were seen after 40 d of fumigation, while the Eridano clone showed visible symptoms of damage after only 15 d of the treatment. Specific activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (E.C. 4.1.1.39) diminished in both the clones, while specific activity of phosphoenolpyruvate carboxylase (E.C. 4.1.1.31) increased. Exposure to O3 also caused a reduction in the specific activity of ribulose-1,5-bisphosphate kinase (E.C. 2.7.1.19) in both clones. At the end of the exposure to O3, specific activity of glyceraldehyde 3-phosphate dehydrogenase (E.C. 1.2.1.13) increased in I-214 and remained similar to the control in Eridano, whereas specific activity of fructose-1,6-bisphosphate phosphatase (E.C. 3.1.3.11) was higher in Eridano and similar to the control in I-214.

Biochemical parameters as biomarkers for the early recognition of environmental pollution on Scots pine trees. II. The antioxidative metabolites ascorbic acid, glutathione, alpha-tocopherol and the enzymes superoxide dismutase and glutathione reductase.

Field investigations with Scots pine trees (Pinus sylvestris L.) were performed in eastern Germany, where ambient SO2, NOx and O3 concentrations differed significantly in 1992-99 at three sites, namely Neuglobsow (yearly mean SO2 in 1992: 9 microg m(-3)), Taura (yearly mean SO2 in 1992: 54 microg m(-3)) and Rösa (yearly mean SO2 in 1992: 73 microg m(-3)). To investigate the effects of SO2, NOx and O3 on antioxidants (superoxide dismutase, ascorbic acid, glutathione, glutathione reductase, alpha-tocopherol) and pigments including chlorophyll fluorescence as well as visible damage symptoms in the form of needle yellowing and tip necroses, needles of the 1st and 2nd age class from young and mature trees were collected at the sites every October. Eight years after the start of the field study in 1992, the ambient SO2 concentrations had decreased significantly at Neuglobsow (yearly mean SO2 in 1999: 4 microg m(-3)), Taura (yearly mean SO2 in 1999: 5 microg m(-3)) and Rösa (yearly mean SO2 in 1999: 5 microg m(-3)). NOx and O3 differed less at the three sites and showed no temporal variations. Whole needle glutathione continuously decreased, although concentrations were higher in needles of the 1st and 2nd age class from the polluted sites Taura and Rösa than the unpolluted site Neuglobsow. The activities of glutathione reductase exhibited the same site-related differences and temporal variations and were correlated with concentrations of oxidized glutathione (GSSG). In contrast, the activities of the enzyme superoxide dismutase and the concentrations of whole needle ascorbic acid remained unchanged over the period. Only at the end of the investigation period did the concentrations of oxidized ascorbic acid (dehydroascorbate) increase in six-month-old needles at the polluted sites Taura and Rösa. Despite the clear decreases in SO2, the visible symptoms of needle tip necroses remained unchanged, especially at the polluted sites Taura and Rösa, although the needles contained higher pigment concentrations than needles from the unpolluted sites. The results of measurements with antioxidants as biomarkers for SO2-mediated stress in pine needles show that the adult Scots pine trees at the polluted sites suffered from greater oxidative stress than the needles from the less polluted site.

Seed treatment with the antioxidant Ambiol enhances membrane protection in seedlings exposed to drought and low temperatures

Because of the harsh environments in boreal clearcuts, it is necessary to plant only stress-tolerant seedlings. To test the use of antioxidants to enhance stress tolerance, Ambiol (2-methyl-4-dimethylaminomethyl-5-hydrohybenzimidazole dihydrochloride) was applied to jack pine (Pinus banksiana Lamb.) and black spruce [Picea mariana (Mill.) BSP], using a 24-h seed soak. For seedlings treated with Ambiol (0, 0.1, and 10 mg l–1), membrane leakage and visible damage were compared following the application of drought (by withholding water), and frost (–10°C for 1.5 h). Although black spruce was more responsive to treatment than jack pine, the effectiveness of Ambiol varied depending on the type of stress, species and the concentration. Ambiol reduced membrane leakage under both drought and frost. The lower (0.1 mg l–1) concentration of Ambiol reduced membrane leakage in black spruce needles under severe drought, while a higher concentration (10 mg l–1) provided more protection when jack pine was exposed to low temperatures. The antioxidant Ambiol enhanced membrane protection and reduced visible damage symptoms in seedlings following the application of stress. The seed-soak method provided a simple, cost-effective, method of conditioning seedlings.

Diagnosis of damage in forest trees by integratedbiochemical parameters

Bioindication can be carried out at different levels, ranging from cell metabolism up to the whole ecosystem. The annual forest damage surveys in several European states are based on bioindication procedures that chiefly use the visual parameters like foliage loss and yellowing. While the visible monitoring of damage is related to the level of the organism as a whole, some biochemical parameters may serve as damage indicators on the level of cell metabolism These indicators may be components of the photosynthetic apparatus, antioxidants, phytohormons, phenolic compounds and parameters that relate to water status. Because of their difference in spatial and temporal dimensions these two methods of bioindication complement each other to a complete picture of the state of vitality of forest trees. Because of their non-uniform assignation to different metabolic processes, an integration of the individual biochemical indicators is necessary. Therefore an index, the biochemical damage index (BDI), was calculated from the estimated threshold values deduced from comparative data from well-known sites and experiments under controlled conditions. In the present study visible damage symptoms and the BDI as an integrated biochemical indicator of tree vitality from six variously damaged trees from each of ten Norway spruce permanent-observation sites located in SW-Germany were compared with six trees from an undamaged reference site during a time-span of three years. Our results confirm that biochemical indication is a reliable tool for diagnosis of damage of forest trees.

Long-term exposure of young spruce and beech trees to 2450-MHz microwave radiation

Young spruce and beech trees were planted in field plots and exposed to 2450-MHz microwave radiation generated by a 600-W magnetron source. Power flux densities (PFD) ranged from 0.007 to 300 W/m 2, depending on the location within the plots. Microwave exposure was permanent during 3.5 years. Heating effects of the microwave radiation were estimated by measuring the hydrolysis rate of exposed sucrose solutions. This method revealed a temperature increase of ∼4°C at the highest PFDs. During the whole exposure period, the microwave radiation caused no visual symptoms of damage. PFD had no effect on crown transparency, a parameter commonly estimated in forest condition inventories. Height growth was similar at all PFDs for both species, as was photosynthesis in beech leaves, determined by chlorophyll fluorescence measurements. A negative relationship existed between foliar concentrations of calcium and sulfur in beech and PFD during the first 2 years of exposure. However, the concentrations of both nutrients remained within the sufficiency range. In the third year of exposure, the effect was absent. The microwave effect on calcium is discussed in connection with literature data.

Replacement of nitrate by ammonium as the nitrogen source increases the salt sensitivity of pea plants. II. Inter‐ and intracellular solute compartmentation in leaflets

ABSTRACTPea plants (Pisum sativum L. cv. ‘Kleine Rheinländerin’) grown on ammonium or nitrate as the sole nitrogen source were treated with 50 mol m−3 NaCl. Four days after salt addition, ammonium‐grown plants developed the first visible damage symptoms (wilting of leaflets, starting from the margins). Salt‐treated, nitrate‐grown plants were not affected during the experimental period. In order to obtain a better understanding of this differential salt sensitivity, we investigated the inter‐ and intracellular ion compartmentation of leaflets under both nutritional conditions by analysing ion concentrations in the apoplastic space, in chloroplasts and in protoplasts. When the leaves of nitrate‐ and ammonium‐grown plants had attained similar sodium and chloride contents (after different times of exposure to salinity), the latter had a considerably lower chloroplastic chloride (and also sulphate) concentration. The results suggest that the intracellular compartmentation capacity of ammonium‐grown plants is considerably lower than that of nitrate‐grown plants. Ion toxicity appeared to initiate breakdown of metabolism in parts of the mesophyll tissue of ammonium‐grown plants, causing an abrupt release of solutes into the apoplast, which coincided with the appearance of visible damage. Although the ammonium concentrations in leaves increased dramatically in the later phases of damage development, they were too low to cause the collapse of electrochemical gradients at the time at which damage became visible. Thus, the reason for a lower compartmentation capacity under ammonium nutrition remains as yet unclear.

Early detection of effects of acid deposition and automobile exhaust on young spruce [Picea abies (L.) Karst.] trees

Rooted spruce cuttings from three clones were sprayed daily with sulfuric acid at pH 2.5 for one month or treated with automobile exhaust for one hour. Foliage samples were extracted and analyzed by high performance liquid chromatography. Chromatographic peaks representing unidentified leaf constituents from treated and control trees were compared. Discriminant analysis indicated a weak but significant difference and Canonical discriminant analysis indicated clear differences between treatments and control. Similar differences were found between the three clones. Visible symptoms of damage were not evident even four months after treatment. This result is important because it demonstrates the possibility of using unidentified plant constituents to detect damage to plants even before visible symptoms appear.

Localised applications of MCPA and glyphosate to young kiwifruit plants

Abstract Kiwifruit plants (Actinidia chinensis) grown in a nursery received localised applications of MCPA or glyphosate on the rootstock portion, 5 cm above the graft union on the scion. on a basal fully expanded leaf and on an apical leaf. MCPA was also applied to the soil surface. Damage produced depended on dose and treated portion of the plant Glyphosate applied either to the scion or to the rootstock did not produce visual damage symptoms in the current season. MCPA at the highest rate was harmful when applied to the rootstock, and safe when sprayed on the scion. Application of MCP A and glyphosate to the basal or apical leaves was much more phytotoxic. Effect of MCPA in the current year was more spectacular than glyphosate damage. On the other hand, damage produced by glyphosate was more noticable than MCP A injury in the year after treatment. The worst damage resulted from basal leaf treatments. MCPA applied to the soil produced plants with malformation of stems and leaves.

The effects of sulphur dioxide on the parasitism of the rust fungus Uromyces viciae-fabae on Vicia faba

Vicia faba cv. Aguadulce was grown in fumigation chambers ventilated with filtered air or air containing sulphur dioxide (SO 2) at controlled concentrations, and inoculated with the rust fungus Uromyces viciae-fabae. The influence of the pollutant was rated in terms of production of uredia and dehiscent urediospores. Exposures to SO 2 levels around 70–90 nl litre −1 enhanced uredia density. Pre-inoculation fumigations at 70–86 nl litre −1 increased uredia density, whilst post-inoculation fumigations stimulated urediospore production. Lower concentrations increased diffusion resistance of the host plant and slightly increased uredia density. Concentrations between 100 and 130 nl litre −1 were somewhat inhibitory for the parasite, even in the absence of any visible damage symptoms on the host. Total sulphur accumulation in leaf tissue was reduced by the presence of the fungal infection. Growing under SO 2 pollution neither decreased germination ability nor modified morphological parameters of the urediospores. However, elongation of the germination tube of spores coming from filtered air was adversely affected by the pollutant.

Pathogenic and non-pathogenic stress effects on peroxidases in leaves of tobacco

The effects of stress stimuli of different sources, including pathogenic (fungi, bacteria, viruses), non-pathogenic (excess of water and manganese, γ-irradiation), as well as senescence, were examined in tobacco leaves. Some of these stimuli produced damage symptoms that differed in severity, whereas others did not produce visible damage symptoms. The activity, molecular heterogeneity, and localization of peroxidases (PO; E.C.1.11.1.7) in tobacco leaf tissues as influenced by stress stimuli were studied, using both biochemical and cytochemical approaches. Chlorophyll and lipid peroxide contents were also determined as related to tissue and cell membrane damage. All stress stimuli and senescene triggered an increase in PO activity. In tobacco-fungi interactions, this increase was a plant response to infection and not a contribution of the hyphal PO per se. The PO increases under stress conditions that caused visible tissue damage symptoms were concomitant with chlorophyll loss. The severity of damage corresponded to the rate of PO increase and chlorophyll loss. Under all stress conditions, increases in PO were accompanied by increased lipid peroxidation, resulting in damage to cell membranes. Thus, the responses of PO in tobacco leaves to various stress situations were shown not to depend on the origin of stress stimuli, but on the presence and degree of damage, suggesting a possible involvement of endogenous cell wall elicitors.

An in vivo analysis of the effect of SO2 fumigation on photosynthesis in Zea mays.

Fumigation of leaves with SO2 can reduce the capacity for photosynthetic CO2 uptake even in the absence of visible symptoms of damage. In vitro studies suggest that this invisible injury to intact leaves could be affected by damage to each of the main stages in the photosynthetic process. Reduced stomatal apertures may also reduce photosynthesis following SO2 fumigation. The responses of CO2 uptake by leaves to intercellular CO2 concentration and to absorbed light provide information for quantitative separation of the in vivo contribution of the different stages of photosynthesis to reduction in overall rate. This study uses these techniques to examine the basis of reduction in CO2 uptake in Zea mays cv. LG11 leaves following short‐term fumigation with SO2. Fumigation with 33 μmol m–3 SO2 for 30 min reduced light saturated CO2 uptake by about one‐third. An even greater reduction in light limited CO2 uptake was observed and with no significant change in light absorptance this was attributed to a reduced quantum yield of photosynthesis. The light saturated CO2 uptake rate and the stomatal conductance decreased in parallel. However, the relationship of CO2 uptake to the intercellular CO2 concentration suggested that the reduced stomatal conductance did not account for the reduced rate of CO2 uptake following fumigation. Both the initial slope and plateau of this relationship were significantly reduced, suggesting that both carboxylation efficiency and capacity for regeneration of CO2 acceptor were diminished by SO2 fumigation. The operating intercellular CO2 concentration indicated that both processes were co‐limiting, before and after fumigation. The time required for induction of photosynthetic CO2 uptake on illumination was approximately doubled following SO2 fumigation, showing that fumigation impairs the ability of the photosynthetic apparatus to adapt to fluctuations in light level.

Causes of Square Abscission in Cotton in Arizona1

Cotton (Gossypium hirsutum L.) plantings sometimes abscise large numbers of flower buds (squares). Many environmental and nutritive stresses and insect or disease damage are known to induce this abscission. To determine the specific causes of abscission in Arizona the squares were examined visually under a ✕ 10 stereomicroscope. Symptoms that indicated the cause of the abscission were observed to fall into four categories: 1) dissolution of tissues due to plant bug (primarily Lygus spp.) feeding, 2) soft rot due to thrips (Thysanoptera spp.) activity, 3) tunnels due to lepidopterous larvae feeding, and 4) desiccation without physical damage indicating physiological stresses. Each week during three seasons (1978 to 1980) the abscised squares were subdivided among these categories. Prior to 15 July the primary cause of abscission was Category 1 with a minor fraction due to Categories 2 and 4. After 15 July Category 3 became more important and Category 2 was seldom observed. In only two sampling periods during the 3 year study did Category 4 exceed half of the abscised squares. Correlation of the Category 1 symptoms with lygus bug population in the field at the beginning of the week of sampling was high (r = 0.94 P < 0.05). The regression analysis indicated a feeding rate of 1.7 squares insect−1 per day−1. Temperature correlation on lygus feeding was not significant. The study showed that visual symptoms of damage can be used to categorize abscised squares by the causal agent and that large variation within and between years occurs.

Effect of gamma radiation on phenylalanine ammonialyase activity and accumulation of phenolic compounds in citrus fruit peel

External layers of citrus fruit peel evinced a marked increase in phenylalanine ammonia-lyase (PAL) activity after irradiation with 200 krad doses of gamma radiation. Maximum enzyme activity was attained one day after irradiation. Thereafter PAL activity rapidly decreased to control values in fruits which did not show visible damage symptoms later upon storage, but remained relatively high for several days in those fruits which later showed peel damage. Accumulation of phenolics in cells was demonstrated and may be explained by the enhanced PAL activity. The connections between irradiation, enzyme activity, phenolics and damage are briefly discussed.