Search

Poa pindariensis, a newly discovered species of Poa (family Poaceae) from Pindari Valley, Western Himalaya, is described and illustrated. Within the genus Poa, the new species belongs to P. subg. Stenopoa sect. Pandemos, and morphologically similar to P. trivialis by the sickle shape of lower glume but differs from the latter in characteristic features of habit, leaf sheath, ligules, panicle and spikelet. Additionally, data on its distribution, habitat, flowering and fruiting are given along with photo plates and distribution maps. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the chemical composition, metabolizable energy, digestibility and ability of gas production of Poa trivialis. Samples was collected at three phenological stages including: vegetative growth, flowering and seedling on two different elevations of 1300 to 1500 m and 2000 to 1800 m asl in Neor and Hir region as the first and second sites, respectively. Testing of gas production was performed using Semi-automatic gas producers machine WT-Binder 87532 Model (made in Germany). Fistulated castrated male sheeps were used for preparation of required rumen fluid. Results show that more crude protein and less cell wall were in the vegetative growth stage. Gas production was higher in the first stage in comparison with other growing stages. The amounts of gas production of soluble and insoluble structures at the first and second sites were 75.63 and 81.50 mL, respectively. Metabolizabe energy of Poa triviali was 2.38 in the first site and in the second site 2.48 Mcal/kg DM in the vegetative growth stage. Collected samples from the second site had more metabolizabe energy, digestibility, degradability and gas production in comparison with the results of the first site. [ABSTRACT FROM AUTHOR]

Invasive alien plants often occur in monospecific stands with high density in the invaded range. Production of bioactive secondary metabolites in such stands could have allelopathic effects on germination of native species. We tested this component of the novel weapon hypothesis for Heracleum mantegazzianum, a prominent invader in Europe, using seeds of 11 native herbs exposed to soil or soil extracts from invaded stands, moist seeds or seed extracts of H. mantegazzianum. There was no effect of the various treatments on germination of most species, while germination was reduced in Urtica dioica on invaded soil, in Poa trivialis with H. mantegazzianum seed extract, and negative effects of the essential oil bergapten were found in three species. In P. trivialis the results of the seed extract were not supported by the experiment with added seeds of the invasive plant. Thus, there is limited evidence for allelopathic effects of the invasive H. mantegazzianum on germination of co-occurring native herbs. [ABSTRACT FROM AUTHOR]

Copyright of Turkish Journal of Biology is the property of Scientific and Technical Research Council of Turkey and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In grass-seed production, the purity of the product is of high importance and a main issue in an integrated strategy is to reduce or eliminate the seedbank of species which are both difficult or impossible to control in a future grass-seed crop, and also difficult to separate from the cultivated species. This study investigated the influence of different simulated soil-tillage practices on persistence of seeds of the two grass species, Poa trivialis and Vulpia myuros, under field conditions. Leaving seeds of the two species at the soil surface reduced the survival of seeds to low levels compared with strategies that involved incorporation of the seeds shortly after seed-shedding. Persistence of P. trivialis seeds increased with increasing depth of incorporation whereas this relationship was more variable for V. myuros. It was concluded that soil-tillage strategies that leave the seeds at the soil surface for 1–2 months reduced the survival of seeds of the two species to low levels compared with strategies that involved a deep incorporation of the seeds shortly after seed-shedding. The study also investigated the possibilities of using the stale seedbed technique to reduce the seedbank of these two species in the autumn ahead of a spring-established grass-seed crop. This method was found to be very effective in reducing the potential risk of contamination from this source. Finally, the study confirmed that P. trivialis has very persistent seeds whereas the persistence of seeds of V. myuros is limited. [ABSTRACT FROM AUTHOR]

The use of plants to remediate crude oil-contaminated soil has been a particular interest in environmental cleansing. Some plants such as grasses have been demonstrated to have better capacity in biodegradation of oil in the soil. In this study the effect of different concentrations (1-15%) of heavy crude oil on germination and growth of Poa trivialis (Rough meadow-grass) was studied. Our results showed that the planting occurred in all crude oil concentrations including 15% heavy crude oil. The heavy crude oil in the soil in both high and low concentrations, could delay germination and reduce the number of germinations, the length and the width of the leaves and also decrease the biomass in vegetated soil. The reduction of the crude oil in the vegetated soil was higher than the non-vegetated soil. The roots of the plants were well distributed in the soil in concentrations up to 3% while it was poorly distributed in 10% and 15% of the crude oil concentrations. The absolute reduction of the oil in 15% vegetated sample was higher than the samples with lower concentrations of the crude oil. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Microbiology is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The forest under-storey herbsAnemone nemorosa,Lamiastrum galeobdolonandVeronica montanaare generally considered indicator species of old, broadleaved woodland sites where the soil fertility is often low. In a glasshouse bioassay, however, all three species not only showed large positive growth responses to supplied P concentrations (0-10?mg?L-1) solutions, but also tolerated high P concentrations (20-40?mg?L-1), well above those normally found in their natural habitat. Plants responded by raising the concentrations of P in their shoot and root tissues and increasing their biomass, resulting in an increased P uptake. A shade-tolerant competitor species,Urticadioica, also grew vigorously across the full range of P concentrations, restricting the growth of the woodland species. This emphasises the difficulty of establishing semi-natural woodland vegetation in the presence of competitor species, for example in situations where new woodlands are planted on fertile ex-agricultural soils containing large residual concentrations of P. The influence of soil pH on the growth and nutrient relations ofA. nemorosa,L. galeobdolon,V. montana, Poa trivialisandU. dioicawas determined in a separate experiment using an ex-arable soil as the growing medium with pH levels adjusted from 7.4 to 5.8 and 4.3 respectively. Acidifying the soil enhanced growth, but reduced the concentrations of N, P and K in the leaves of all three woodland species, probably due to dilution of these minerals in the increased dry matter production. The competitor species (P. trivialisandU. dioica) responded in similar manner to the woodland indicator species. These results suggest that manipulating soil pH as a means of facilitating the establishment of woodland indicator species in new farm woods is unlikely, in the short term, to be effective where competitor species are present. [ABSTRACT FROM AUTHOR]

The C3 grass Poa trivialis and the C4 grass Panicum maximum were grown in sand culture and received a complete nutrient solution with nitrogen supplied as 1.5 mol m-3 NH4NO3. 15N tracer techniques were used to quantify the relative use of root uptake and mobilization in supplying nitrogen to growing leaves in intact plants which either continued to receive nitrogen or which received the complete nutrient solution without nitrogen. The allocation of both 15N-labelled nitrogen uptake and unlabelled mobilized nitrogen indicated that, under their conditions of growth, the sink strength of growing leaves was relatively greater in P. maximum than P. trivialis. The supply of nitrogen by mobilization to side tillers of P. trivialis was completely stopped as the external nitrogen supply was reduced, whilst in P. maximum some allocation of mobilized nitrogen to side tillers, roots and growing leaves was maintained. In both plant species receiving an uninterrupted supply of nitrogen the allocation pattern of mobilized nitrogen differed from that of nitrogen derived from root uptake. Differences exist in the degree to which P. trivialis and P. maximum utilized uptake and mobilization to supply nitrogen to the growing leaves. In P. trivialis roots were always a net sink of mobilized nitrogen, irrespective of the external nitrogen supply. In P. maximum, roots were a net sink of mobilized nitrogen when external nitrogen was withdrawn, but exhibited both source and sink behaviour when nitrogen supply was continued. [ABSTRACT FROM AUTHOR]