Biological Decline of Solanum nigrum L. Due to Tobacco Mosaic Tobamovirus (TMV) Infection I. Growth and Nutrient Uptake

The aim of our study was to examine the effect of tobacco mosaic tobamovirus (TMV) infection on the growth and nutrient content of S. nigrum leaves. TMV infection significantly reduced the height, the fresh and dry weight of both the shoots and roots. The height of the shoots was reduced by 53% as compared to control. Reduction in fresh and dry weight of shoots and roots due to virus infection varied between 78 and 82%. There was no significant difference in the nitrogen (N), phosphorus (P) and calcium (Ca) content of the healthy and virus infected leaves of S. nigrum. The sodium (Na), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn) and copper (Cu) content of the leaves significantly reduced due to virus infection. Opposite effect was observed in case of potassium (K) content, which were considerably enhanced in the TMV infected leaves

Invasion impact is conditioned by initial vegetation states

Abstract Biological invasion is a crucial problem in the world because of its negative consequences for protected areas. The degradation stage of vegetation might affect the success of invasion. One of the most abundant and threatening invasive species is the common milkweed (Asclepias syriaca L.) which has invaded already 23 countries of Europe and in several habitat types its further spreading is promoted by climate change. Pannonian sand grassland is one of the most threatened habitat by common milkweed invasion. Therefore, invasion in sand grassland vegetation is an important issue. However, the effects of the invasive plant in the open sand grassland are rather controversial. In order to clarify the existing contradictory results, the study was carried out in a strictly protected area, near Fülöpháza (Hungary) in a reserve core area in a UNESCO biosphere reserve. Microcoenological study was applied to determinate the fine-scale community characteristics of non-invaded and invaded stands in natural and seminatural vegetation and data were processed by Juhász-Nagy's information theory models. Shannon diversity of species combinations (compositional diversity) which describes the ways of the coexistence of species, and the number of realized species combinations were used for measuring beta diversity. Differences between stands were analyzed by two-way ANOVA. The maximum compositional diversity of species and main life-forms (annuals, perennials and cryptogams) did not differ significantly between the non-invaded and invaded stands. In contrast, significantly larger characteristic areas of compositional diversity were detected in the invaded stands. Based on these results, it could be concluded that diversity of species combinations did not change but those values have shifted to coarser scales in case of invaded stands. The direction of this change suggests a kind of impoverishment in the presence of Asclepias. Thus, it is worth mentioning from the invasion management point of view that protection of the habitats against disturbance is a more cost-effective and successful way than protection against the establishment or extirpation of invasive species, since disturbance facilitates the invasions throughout the impoverishment of the community

Seed viability of common ragweed (Ambrosia artemisiifolia L.) is affected by seed origin and age, but also by testing method and laboratory

Plant science

Book reviews

G. Loebenstein, P. H. Berger, A. A. Brunt and R. H. Lawson (eds): Virus and Virus-like Diseases of Potatoes and Production of Seed-Potatoes. Kluwer Academic Publ., Dordrecht (The Netherlands), 2001, 460 pp. László Nowinszky (ed.): The Handbook of Light Trapping. Savaria University Press, Szombathely, 2003

Book Review

Albrechtsen, S. E.: Testing Methods for Seed-Transmitted Viruses: Principles and Protocols. CABI Publishing, Wallingford, UK, 2006. 268 pp. (US 100.00

Translocation of diquat dibromide

The aims of our work were to answer the following questions: 1. Diquat dibromide at different concentrations is a contact or systemic herbicide? 2. if translocation occurs what is the extent and direction of it. 3. by what concentration it is translocated in hydroponics. It has been stated that diquat dibromide at different dilutions (40-5%) had systemic effect in Robinia pseudo-acacia in the fields. Its translocation has been occurred apically first, and later basipetally. The extent of translocation depended on the concentration. In hydroponics diquat dibromide has crytallized on the leaf surface of Galinsoga parvif lora and all concentrations (40-0.078%) proved lethal. Recognition and application of systemic characteristics of diquat dibromide is reported here for the first time. Improvement of application method is in the focus of our future work

New data about the virus susceptibility of some Chenopodium species

The aim of our study was to investigate the susceptibility of some Chenopodium species (Chenopodium album, C. glaucum, C. berlandieri, C. ugandae) to six viruses (Alfalfa mosaic virus, Cucumber mosaic virus, Obuda pepper virus, Potato virus Y, Sowbane mosaic virus, Zucchini yellow mosaic virus). Fourteen plants of each species were mechanically inoculated and virus susceptibility was evaluated on the basis of symptoms and back inoculation. A series of new host-virus relations were determined

Experiments on the Resistance or Pepper Cultivars to Macrophomina phaseolina

The ashy stern blight of pepper (Capsicum annuum) is often caused by Macrophomina phaseolina. Serious wilt disease occurred between 1994 and 1996 of pepper plants in Hungary. In 1996-98 screening experiments were made on many pepper cultivars. Culture (Knopp) solution experiments, pot experiments, greenhouse and field trials were carried out. We determined the incidence of disease by visual examinations, testing on PDA culture, and light microscope. There were significant differences in susceptibility of cultivars and breeding materials. &nbsp