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1.
One of the economically important diseases of lettuce is lettuce big-vein disease (LBVD), which leads to severe yield losses. LBVD is associated with a complex of two viruses, Lettuce big-vein associated virus (LBVaV) and Mirafiori lettuce big-vein virus (MLBVV). These viruses are transmitted by motile zoospores of Olpidium spp. fungi, which persist in the soil for decades through resting spores. In greenhouse and field experiments, this study tested whether changing plant and soil temperatures together with fungicide application would have a significant effect on controlling LBVD in lettuce. Soil fumigation with metam sodium was not effective at controlling the disease, as opposed to treatment with chloropicrin and methyl bromide. Moreover, the fungicides carbendazim and fluazinam were effective in reducing the incidence of Olpidium virulentus. Nevertheless, control of the fungal vector did not seem to be sufficient to control the disease due to the transition ability of the virus under low vector abundance. Crop covers, which affect the favourable environmental conditions for the viruses by lowering soil temperature and raising air temperature, reduced the disease symptoms. Combining fungicides with crop cover had a synergistic effect on reducing disease symptoms, thus providing a sustainable solution for LBVD.  相似文献   
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Mal secco disease of citrus caused by Phoma tracheiphila is a devastating disease in the Mediterranean basin. Susceptible citrus species include lemon, citron, lime and others. Trees attacked by the fungus show characteristic symptoms; the smallest twigs die first, followed by the larger branches. Eventually, the whole tree is killed. The symptoms are clear in the orchards but by the time they are visible the disease is already well established. The need for a sensitive, reliable and rapid diagnostic method for the early identification of the fungus in trees and fruit exists. We have developed a PCR-based method for the identification of P. tracheiphila from plant tissues including fruit. Any such method must take into account the genetic variability in the pathogen population. Molecular methods were used to compare different isolates of P. tracheiphila. This study found no significant differences between different isolates from different citrus species from different parts of Israel.  相似文献   
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Drylands are regarded as highly sensitive to climatic change. The putative positive relationship between average annual rainfall and runoff, assumed for areas between 100 and 300 mm ignores the fact that climatic change in drylands is not limited to climatic factors alone, but is often accompanied by a parallel change in surface properties. Data on rainfall, runoff and soil moisture regime were collected at five monitoring sites in a sandy area, along a rainfall gradient from 86 to 160 mm. Despite the uniform sandy substratum the frequency and magnitude of runoff declined with increasing annual rainfall. Under wetter conditions a thick topsoil biological crust develops. This crust is able to absorb and retain large rain amounts, limiting the depth to which water can penetrate, and therefore water availability for the perennial vegetation. In the drier area, the thin crust can absorb only limited rain amounts, resulting in surface runoff and deeper water infiltration at run-on areas. Our findings demonstrate the important role played by different types of biological soil crusts along the rainfall gradient considered, and question the generally held belief that higher rainfall necessarily leads to deeper water infiltration in sandy arid areas; and higher water availability for the perennial vegetation.  相似文献   
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In order to elucidate whether infection by Bovine Leukemia Virus (BLV) might induce an immunodeficient state, we inoculated sixteen calves with BLV. The calves were followed up for two years and were tested for humoral and cellular responses using various parameters, namely the appearance of antibodies to the BLV antigens, the changes in the numbers of lymphocytes involved, and the ratio between the two main populations of lymphocytes. Antibodies to the BLV antigens were of both the IgG and the IgM classes of immunoglobulins. The levels of antibodies of the IgM class were higher than those of IgG. There was a temporary decrease of reactive antibodies to the BLV antigens, to below detectable levels, during the 14-24 weeks post infection. A significant decrease in the level of plasma IgM was found in all BLV infected calves exhibiting lymphocytosis, while the level of IgG in the plasma of all experimental calves did not diverge significantly from the initial values, throughout the experiment. BLV infection was followed by lymphocytosis of B-cells in most infected calves, which persisted for the whole course of the experiment, while a decrease in the population of T-cells in peripheral blood was observed for a period of several months in all infected calves.  相似文献   
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The effects of natural antioxidants on nitric oxide (NO) modulation and oxidative status were determined in rat epithelial lung cells (L-2). Cells were stimulated with cytokines and treated with one of the following: resveratrol, soybean saponin group B (SSB), quercetin, genistein, olive leaf polyphenol concentrate (OLPC), or N-acetyl-L-cystein (NAC). NAC had no effect on NO levels, whereas resveratrol and OLPC were found to be effective in reducing nitrite levels, modifying iNOS mRNA, and decreasing free radical production. OLPC affected the levels of MnSOD while resveratrol did not, indicating that they act via different pathways. Quercetin and genistein reduced nitrite levels without affecting iNOS levels, presumably by scavenging NO. SSB did not affect nitrite levels, but exposure did reduce iNOS mRNA expression and protein levels, possibly due to antioxidant activity. Naturally occurring antioxidants, in particular resveratrol and OLPC, may have therapeutic potential in the treatment of inflammatory diseases.  相似文献   
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? Municipal solid waste compost has been widely utilized in Israel in the production of field crops and reclamation of saline soils. This paper reviews laboratory and field studies defining the conditions under which an added compost improves the physical properties of soils and increases yields of crops. Specific attention is given to how applications of MSW compost to compacted, structurally deficient soils can lead to consistent improvement. Data are also provided on optimum C/N ratios of composts and optimum application rates under conditions studies in the research.  相似文献   
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Catenary changes, archeology, micromorphology, and magnetic mineralogy of paleosols in coastal sands, Israel, were investigated under chronostratigraphic control by available luminescence datings from adjacent sites. At the outlet of Hadera stream, eolianites (Hebrew: “kurkar”) underlie paleosols with Epipaleolithic (approx. 17–20 ky) artifacts at the top and occasional Mousterian (>40 ky) artifacts in the subsoil. The optically stimulated–luminescence/infrared stimulated–luminescence (OSL/IRSL) dates (>50–12 ky) from adjacent sites roughly agree with the archeological findings. The paleosols show a magnetically depleted Vertisol superimposed on a magnetically enhanced cumulative Chromic Luvisol (WRB) (USDA: Rhodoxeralf, Israeli class.: Hamra). The latter contain approx. 0.25 mm thick, isotropic clay infillings distinctly separated from the soil matrix. These infillings are tentatively interpreted as the result of strong environmental disturbances, such as surface desiccation, subsequent waterlogging, and enhanced dust deposition, presumably at the time of the Last Glacial Maximum. In addition to the massive accumulation of eolian dust, diverse pedogeomorphic changes lagging in time from the onset of climatic deterioration may have taken place in coastal settings. Recurrent desiccation cracks may have exposed subsurface materials repeatedly to sunlight, consequently resetting the luminescence signal. The eolianite sequences are thus distinct from loess/paleosol sequences from temperate climates and have to be treated more rigorously at a site‐specific level.  相似文献   
10.
Drip lines were located at distances ranging from 0 to 60 cm from one or both sides of a row of pepper plantlets, and we monitored the effects on their shoot development during 76 days from transplanting to full-size first fruits, on the final root system, and on the areal water and salt distributions in the upper 15-cm soil layer. The experiment was conducted in a greenhouse with a sandy soil, and excess fresh water (1.9 L d−1 per plant) was applied via short daily irrigations. In addition, the effects of watering distance and symmetry on the potential water uptake rate were analyzed with a coupled-source-sink steady flow and uptake model. Initial faster shoot growth with the one-side system and short distances progressively changed to faster growth with the two-side system and longer watering distances, with the optimum at 30-40 cm. These temporal changes are attributed to temporal changes in the root uptake of irrigation water: small plants with small root systems benefit from the larger water supply to a smaller soil volume provided by the one-side system, whereas larger plants with greater water needs could extract more irrigation water when they developed larger, split root systems in the two-side irrigation. Balanced root systems and maximal shoot growth can be obtained by starting the irrigation with a line on each side, near the plants, and moving the lines after a short time.  相似文献   
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