Aims A molecular genetic distance study has been used in an initial survey to identify subspecies and genotypes of the weed Acacia nilotica in Australia, information needed to find suitable ...biocontrol agents. We use patterns of DNA sequence variation (in two DNA fragments) from each of the nine described subspecies of Acacia nilotica (L.) Delile (Leguminosae: Mimosoideae) that is to determine their genetic similarity, to verify if the Australian populations are A. nilotica ssp. indica (Benth.) Brenan, and to establish if any other subspecies are present in Australia. Location Australia and southern Africa through the Arabian peninsular to the Indo-Pakistan subcontinent. Methods Representative specimens from the global distribution of the nine A. nilotica subspecies were sourced primarily from herbaria sheet specimens where available, and secondarily from field collections. These specimens together with related outgroups from Mimosoideae were genetically analysed using the DNA fragments trnL and internal transcribed spacer one (ITS1). We calculated a similarity index as set out in PAUP using UPGMA (Unweighted Pair-Group Method Arithmetic average) methods to cluster taxa to produce a genetic distance phenogram. Results Sequence results from ITS1 and trnL DNA fragments identified seven of the described subspecies of A. nilotica. Acacia nilotica ssp. cupressiformis (J. Stewart) Ali & Faruqi and A. nilotica ssp. adstringens (Schumach. & Thonn.) Roberty were not found to be genotypically distinct from A. nilotica ssp. indica and A. nilotica ssp. nilotica, respectively, based on the two DNA fragments. Subspecific ITS1 genotypes were geographically distributed similarly to previous reports that were based on morphology, with the exception that the hemispherica ITS1 genotype also occurred in Somalia. We confirmed that the Australian A. nilotica populations are mostly comprised of subspecies indica, but in addition, some individuals were found to be genetically identical to an unidentified Pakistan genotype not previously reported as occurring in Australia. Main conclusions Australian A. nilotica populations originated from India and Pakistan and we recommend further analysis to determine the complete genetic diversity profile and origins of the Australian populations. We highlight the importance of determining any hybridization between Australian populations of A. nilotica and native subgenus Acacia species. This study demonstrates the importance of genotyping weed species targeted for biocontrol and/or listed host specificity test species that may be easily misidentified. Biocontrol practitioners can justify genetic studies by considering the costs should a project fail through misidentification.
1. Animals usually require information about the current state of their habitat to optimize their behaviour. For this, they can use a learning process through which their estimate is continually ...updated according to the cues they perceive. Identifying these cues is a long-standing but still inveterate challenge for ecologists. 2. The use of plant cues by aphid parasitoids for the assessment of habitat profitability and the adaptation of patch exploitation was studied. Grounding on predictions from optimal foraging theory, we tested whether parasitoids exploited host patches less intensively after visiting heavily infested plants than after visiting plants bearing fewer aphids. 3. As predicted, after visiting heavily infested plants parasitoids reduced their residence time and attacked fewer hosts in the next patch. This was the case regardless of whether the aphids were actually present on the first plant, indicating that the cue came from the plant. Moreover, the level of infestation of a plant at some distance from the first plant visited affected parasitoid patch exploitation on the second plant in a similar manner, indicating that the cue was volatile. 4. These results highlight a novel role of herbivore-induced volatiles in parasitoid foraging behaviour, different from the widely studied attraction at a distance.
Purpose: to assess environmental and agrochemical indicators of sewage sludge from municipal wastewater treatment plants through phytotesting. Materials and methods. Sewage sludge from municipal ...wastewater treatment plants with a three-year stay on the sludge map was studied. The examined sludge contains a high amount of sulfate ions (0.720 g/100 g) with a content of calcium ions of 0.350 g/100 g. The remaining salt ions and heavy metals are in small quantities. Phytotesting was carried out by studying the phytoresponse of the test plants seeds in contact with an aqueous extract and directly with precipitation. In the first variant, solutions of various concentrations were prepared: an aqueous extract of sediments, its two-fold dilution and four-and eight-fold dilution. To control the indicators, the distilled water and one-component model solutions of sodium sulfate with concentrations identical to the tested solutions were used. Testing was carried out on the seeds of oats and vetch. In the second variant, under laboratory conditions, seeds of oats, vetch, white mustard, radish and watercress were sown in vegetation vessels with sewage sludge. Results and discussion. Phytotesting allowed revealing the complex effect of precipitation due to their composition. In the variant of undiluted aqueous extract from sewage sludge, the inhibitory effect of sulfates on seed germination and biomass growth is revealed. In the variant with two-fold dilution, the stimulating effect of precipitation components on seed germination and biomass growth was noted. To clarify the effect of the stimulating effect of sewage sludge, an experiment on sowing test plants directly into the sludge was carried out. The best indicators were noted in the variants with oats sowing. Conclusions. The inhibitory effect of sewage sludge from municipal wastewater treatment plants in Novocherkassk is due to the content of sulfates in them. The best comparability of indicators in both variants was noted for oat seeds.
Four granular fertilisers were produced from industrial waste products, such as CaSO
∙ 2H
O and FeSO
∙ 7H
O, coniferous and deciduous sawdust mixture and municipal sewage sludge with addition of ...mineral fertilisers. Based on the content of organic matter, nitrogen, phosphorus and potassium and heavy metals, these granular fertilisers can be included into the group of organic-mineral fertilisers. In order to determine their manurial value, a vegetation experiment was carried out with these granular fertilisers in which spring rape and spring triticale were the test plants. The study results show that granular fertilisers increased signifi cantly the yields of test plants and their content of macroelements. The granular fertilisers containing FeSO
∙ 7H
O increased signifi cantly the yields of test plants and the contents of macroelements when compared to those with CaSO
∙ 2H
O. As affected by the granular fertilisers containing CaSO
∙ 2H
O, there was more phosphorus, calcium and sulphur in the test plants. The granular fertilisers composed of the waste products mentioned above can be a cheap source of organic matter and nutrients for plants and may reduce possibility of environmental contamination.
Two independent experiments were conducted to investigate the influence of rhizosphere bacteria on the growth of Anthoxanthum odoratum and Panicum sphaero-carpon. We tested whether host-specific ...populations of Bacillus mycoides affected the growth of their Anthoxanthum and Panicum hosts and whether host-specific differences in Bacillus populations modified the strong detrimental effect of the root fungal pathogen, Pythium macrosporum. Our results showed both positive and negative effects of Bacillus inoculation and that Anthoxanthum and Panicum plants responded differently to Bacillus isolates that originated from different host plants. Anthoxanthum grew relatively better with isolates from Panicum, while Panicum grew relatively better with isolates from Anthoxanthum, consistent with a negative feedback. In both experiments Pythium infection was detrimental to plant growth, and Panicum was more negatively affected by inoculation with Pythium. Overall, Bacillus ameliorated the pathogenic effect of Pythium. However, there was no evidence that host-specific Bacillus populations had different effects on the interaction between these plant species and Pythium. Both host-specific differences in rhizosphere bacteria and host-specific accumulation of a fungal pathogen can generate negative feedback between these two plant species.
In a pot experiment, we have studied the effect of an organic manure, Bactofil®A10 and an artificial fertilizer with Ca(NO3)2content on two different soil types (humus sandy, calcareous chernozem). ...Rye-grass was used as a test plant(Lolium perenne L.). Both treatments satisfied the nutrient requirement of the test plant. The Bactofil treatments had a favourable effect on the total number of bacteria and the number of nitrifying bacteria in both soils and on the biomass N content of the humus sandy soil. The enzyme activity of urease was increased in both soil types by the Ca(NO3)2treatment. The amount of plant biomass increased as a result of the treatments. In the statistical evaluation, relationships were found between the changes in the soil parameters due to the treatments and the amount of plant biomass.
We have studied the effect of the different dosages of bentonite, in addition to basic treatments, on acidic sandy soil. Our test plant was rye-grass(Lolium perenne L.). Both regarding the changes in ...the soil nutrient content and microbial activity, small and medium dosages proved to be the most effective. The highest plant biomass was obtained in the medium dosage treatment. In the statistical evaluation we verified a relationship between the studied soil characteristics and the amount of plant biomass.
The almost simultaneous outbreaks of Pepino mosaic virus in tomato crops in different European and non-European countries, was reason to have a closer look at the relationship between these isolates ...and the original isolate from pepino. Fifteen isolates from tomato from different locations and the original pepino isolate, were compared on the basis of their symptomatology on a series of plant species. In addition, PCR fragments derived from the viral polymerase gene were sequenced and aligned. Both studies showed that the isolates from tomato clearly differed from the pepino isolate. The different tomato isolates, however, exhibited only minor differences to each other, both in symptomatology and nucleotide sequence. These results support the conclusion that the tomato isolates should be considered as a distinct strain (Mumford and Metcalfe (2001) Archives of Virology 146: 2455-2460; Van der Vlugt et al. (2000) Plant Disease 84: 103; Van der Vlugt et al. (2002) Bulletin OEPP/EPPO Bulletin 32: 503-508). Moreover, the high similarity of the different tomato isolates suggests the existence of a common source of infection for the recent outbreaks.PUBLICATION ABSTRACT
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