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G. Kritzman A. Shani-Cahani B. Kirshner Yehudit Riven Z. Bar J. Katan A. Grinstein 《Phytoparasitica》1996,24(4):293-304
Peanut pod wart, a relatively new disease to peanut culture, was first reported in Israel in 1988 attacking peanut plants and causing dark warts on the pod. The causal agents are variousStreptomyces spp. Scanning electron microscopy showed a significant difference between healthy and diseased tissues of the exocarp and mesocarp layers of the pod; there were no effects on the endocarp layer. The mesocarp cells of infected tissue were smaller and more compressed than those of healthy tissue. In most cases two cells under the peak of the wart were extremely large and the cells growing from them toward the surface were uneven, forming the shape of a fan. The pathogen could be isolated from the soil and rhizosphere, but in the pod it was found only in the waited tissue. The microorganisms isolated from the warts belong to different groups ofStreptomyces spp.; subsequent pathogenicity tests proved their virulence to a limited host range. In potato, these isolates ofStreptomyces spp. caused deep pitted scab; in peanuts they caused warts. Peanut seeds which developed in infected pods were free of the pathogen if the shell was undamaged. However, the pathogen is surface seedborne, and contaminated seeds during the mechanical cracking process. 相似文献
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Boris Marioni José António L. Barão-Nóbrega Robinson Botero-Arias Fábio Muniz Zilca Campos Ronis Da Silveira William E. Magnusson Francisco Villamarín 《水产资源保护:海洋与淡水生态系统》2021,31(12):1056-1067
- Crocodilians represent one of the oldest extant vertebrate lineages. They have co-existed with humans throughout the Amazon basin for thousands of years, often having a strong cultural and economic influence on people's lives. Shifts in the socio-economic and political reality of the Amazon basin during the last century have led crocodilian populations to face large variations in their numbers according to different levels of exploitation and strategies for their conservation.
- This article reviews the scientific knowledge obtained between 1945 and 2019 on the biology, conservation and management for the four Amazonian crocodilian (caiman) species (Caiman crocodilus, Melanosuchus niger, Paleosuchus palpebrosus and Paleosuchus trigonatus). It provides a general overview on past and current population status and research efforts involving caimans in the Amazon basin and discusses perspectives for the future.
- The most significant studies on the ecology, genetics and management strategies are examined in more detail and this information is contextualized to provide an overview of the most relevant findings that might explain caiman population trends over the last 75 years.
- Systems for sustainable management in the Amazon basin have been discussed for the past 20 years, but remain rarely applicable. It is necessary to develop new ways to maintain healthy caiman populations through innovative management programmes. Sustainable harvesting of wildlife has been shown to promote conservation targets, especially those initiatives based on community co-management. In this article, we propose some general guidelines for future management schemes, in the expectation that the information provided by the scientific community will be considered fully without political agendas determining the priorities.
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Amrakh I. Mamedov Benayahu Bar‐Yosef Irit Levkovich Rivka Rosenberg Avner Silber Pinchas Fine Guy J. Levy 《Land Degradation \u0026amp; Development》2016,27(6):1629-1639
Application of organic wastes to cultivated lands can replace mineral fertilizers but may also alter soil physical properties and enhance pollution potential. The objective of this study was to investigate the effects of biosolids [composted manure (MC) and activated sludge (AS)] and specific biosolid component [orthophosphate (OP), phytic acid (PA) and humic acid (HA)] application on soils differing in texture [loamy‐sand (Ramat‐HaKovesh, RH), loam (Gilat, GL) and clay (Bet‐Dagan, BD)], infiltration rate, runoff volume and soil sediment loss. The soils were packed in erosion boxes (400 × 200 × 40 mm) and subjected to six consecutive simulated rainstorms, each of 186 mm deionized water. The results showed that runoff volume and sediment loss from untreated soils increased with increasing clay contents. In treated soils, the response to AS application differed from the response to other amendments; in the BD clay and GL loam, it was the only amendment that caused a decrease in sediment removed by runoff. In the RH loamy‐sand, all amendments reduced the final infiltration rate, but only AS and HA increased the measured runoff. It is proposed that the difference in the response of the soils to the amendments is associated with the soil's ability to attenuate changes in the negative charge on the clay edges following the increase in the specific adsorption of charged anions, thus controlling clay swelling and maintaining aggregate integrity. The effects of amending soils with a source of organic matter in order to control runoff and soil erosion are not straight forward and depend on soil and amendment properties. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Przemysław Barłóg 《Journal of plant nutrition》2016,39(1):1-16
High yield of sugar beet require adequate mineral nutrition. To be diagnosed across interacting nutrients using appropriate interpretation models, the plant must be sampled at a critical physiological stage. This study aimed to develop and validate norms at the 7-leaf and well-developed rosette stages, for diagnostic purposes using the Diagnosis and Recommended Integrated System (DRIS) and Compositional Nutrient Diagnosis based on centered log ratios (CND-clr). Data on nutrient concentrations and plant performance were obtained from 409 plots in West-Central Poland. With respect to the growth stages, for physiological and practical reasons, the 7-leaf stage is preferable for diagnostic purposes. At this growth stage, the high-yield subpopulation characterized by higher concentration of potassium and sodium compared to other nutrients. CND-clr indices were closely related to DRIS indices (R2 > 0.93). The CND-clr indices, however, better explained the differences in the white sugar yield within the validated dataset than the DRIS indices. 相似文献
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The genotoxic potential of tannery waste water was evaluated by means of the induction of gene conversion and point mutation in Saccharomyces cerevisiae D7 strain. Neither a toxic nor a genotoxic response was obtained after a 2 hr incubation of raw water samples with the strain. A dose-related increase in the induced gene conversion and mitotic reversion was obtained when dilutions of the raw effluent were incubated for 24 hr. Samples of the waste water were also passed through an XAD2 resin column. The column was sequentially eluted with ethyl ether, chloroform and methanol. The ether and methanol fractions showed a positive genotoxic response. 相似文献
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Pascual JI Méndez J Gómez-Herrero J Baró AM Garcia N Landman U Luedtke WD Bogachek EN Cheng HP 《Science (New York, N.Y.)》1995,267(5205):1793-1795
Material structures of reduced dimensions exhibit electrical and mechanical properties different from those in the bulk. Measurements of room-temperature electronic transport in pulled metallic nanowires are presented, demonstrating that the conductance characteristics depend on the length, lateral dimensions, state and degree of disorder, and elongation mechanism of the wire. Conductance during the elongation of short wires (length l approximately 50 angstroms) exhibits periodic quantization steps with characteristic dips, correlating with the order-disorder states of layers of atoms in the wire predicted by molecular dynamics simulations. The resistance R of wires as long as l approximately 400 angstroms exhibits localization characteristics with In R(l) approximately l(2). 相似文献
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1. The effect of age on ovarian function was studied in 245-, 350-, 500-, 700- and 800-d-old Lohmann hens. The effect of three different methods for moult induction on ovarian function and corticosterone concentration was studied in 500-d-old hens. 2. No significant reductions in ovarian weight or in number of follicles before the age of 700 d were found. The ability to produce progesterone and oestradiol-17beta was unchanged up to the age of 700 d and the circadian secretion of these two steroids was identical in young (225 d) and old hens (600 d). 3. The effects of induced moulting by feed withdrawal (FW) and a high Zn (HZn) diet on body weight and ovarian function were very similar; those of a moderate Zn with low Ca (MZn/LCa) diet were smaller. 4. The first significant effect of moulting was a decrease in oestradiol-17beta plasma concentration (d 2). Plasma progesterone decreased more gradually than oestradiol-17beta, and reached a nadir on d 6 in FW- and HZn-treated hens and on d 9 in MZn/LCa-treated ones. 5. Hens treated with either FW or the MZn/LCa, but not those with the HZn diet, showed a very sharp rise in corticosterone concentration on d 2 of treatment. Thus the MZn/LCa diet was less efficient than the other treatments in induction of ovarian involution, but had a similar effect on stress induction, as indicated by increases in plasma corticosterone. 相似文献