Selenium and Sulphur Concentrations in Primary Growths of Different Plant Communities

The factorised evaluated data of seven different grassland swards and two harvest dates of primary growths led to following results: Regarding the concentrations of selenium and sulphur, a selenium antagonist, and the N/S ratio, there were no significant plant community x harvest date, plant community x year, and harvest date x year interactions. The selenium concentrations, which never met the requirements of ruminants, were the highest in young herbage of a Bromion racemosi community reaching 49 µg kg-1 DM. The average of all swards and treatments was 33 µg kg-1 DM of selenium. Apparently, repeated application of selenate-bearing fertiliser is worthwhile in extensive grazing systems. Sulphur concentrations met the requirements of ruminants throughout. Because of the N/S ratio \u3c 15,7 the effect of additional sulphur supply is limited. Thus sulphur should not be fertilised, when selenium-bearing fertilisers are applied

Impact of long-term nutrient supply on plant species diversity in grassland: an experimental approach on conventionally used pastures

The research was initiated to determine the impact of long-term (16 years) differentiated N, P, K supply on the floristic diversity of conventionally used pastures classified as Lolio-Cynosuretum. At four different sites the factors N supply (0, 160 and 320 kg N ha-1 a-1), P supply (0.26 and 52 kg P ha-1 a-1) and K supply (0.66 and 133 kg K ha-1 a-1) were tested in 27 different supply combinations in a factorial design with three replicates. Dry matter (DM) yields of the 1st cut, soil chemical values (pH, P and K concentrations) and the number of species were determined.Site-independent N fertilisation had the largest influence on the diversity, reducing the number of species as a consequence of light competition due to an increase in biomass productivity as well as a decrease in soil pH-levels. Mostly, also the factor K had a significant effect. Recorded species numbers ranged from 7 up to 35 species 25 m-2. On most sites a ‘humpback relationship’ (unimodal relationship) could be observed between productivity and the species number, with maximum species numbers reached with first cut yield levels between 2.5 and 3.5 t DM ha-1. The humpback relationship between productivity and species richness however was not a curve, but an envelope filled with points, indicating that besides productivity also other factors influence the attained species number. In this view the highest number of species were recorded in case of a co-limitation of N and K, indicated by a N:K ratio in the above ground biomass between 1 and 1.5, as well as soil pH-levels between 4.5 and 5.5

Forage as a Primary Source of Mycotoxins in Animal Diets

The issue of moulds and, thus, contamination with mycotoxins is very topical, particularly in connexion with forages from grass stands used at the end of the growing season. Deoxynivalenol (DON), zearalenone (ZEA), fumonisins (FUM) and aflatoxins (AFL) are among the most common mycotoxins. The aim of the paper was to determine concentrations of mycotoxins in selected grasses (Lolium perenne, Festulolium pabulare, Festulolium braunii) and their mixtures with Festuca rubra an/or Poa pratensis during the growing season as a marker of grass safety, which was assessed according to content of the aforementioned mycotoxins. During the growing season grass forage was contaminated with mycotoxins, most of all by DON and ZEA. The contents of AFL and FUM were zero or below the limit of quantification. Moreover, the level of the occurrence of mould was quantified as ergosterol content, which was higher at the specific date of cut. All results were statistically processed and significant changes were discussed

Antioxidant capacity of Macaronesian traditional medicinal plants

The use of many traditional medicinal plants is often hampered by the absence of a proper biochemical characterization, essential to identify the bioactive compounds present. The leaves from five species endemic to the Macaronesian islands with recognized ethnobotanical applications were analysed: Apollonias barbujana (Cav.) Bornm., Ocotea foetens (Ainton) Baill, Prunus azorica (Mouill.) Rivas-Mart., Lousã, Fern. Prieto, E. Días, J.C. Costa & C. Aguiar, Rumex maderensis Lowe and Plantago arborescens Poir. subsp. maderensis (Dcne.) A. Hans. et Kunk.. Since oxidative stress is a common feature of most diseases traditionally treated by these plants, it is important to assess their antioxidant capacity and determine the molecules responsible for this capacity. In this study, the antioxidant capacity of these plants against two of the most important reactive species in human body (hydroxyl and peroxyl radicals) was determined. To trace the antioxidant origin total phenol and flavonoid contents as well as the polyphenolic profile and the amount of trace elements were determined. There was a wide variation among the species analysed in what concerns their total leaf phenol and flavonoid contents. From the High Performance Liquid Chromatography (HPLC) electrochemically detected peaks it was possible to attribute to flavonoids the antioxidant capacity detected in A. barbujana, O. foetens, R. maderensis and P. azorica extracts. These potential reactive flavonoids were identified for A. barbujana, R. maderensis and P. azorica. For R. maderensis a high content (7 mg g-1 dry weight) of L-ascorbic acid, an already described antioxidant phytomolecule, was found. A high content in selenomethionine (414.35 μg g-1 dry weight) was obtained for P. arborescens subsp. maderensis extract. This selenocompound is already described as a hydroxyl radical scavenger is reported in this work as also possessing peroxyl radical scavenging capacity. This work is a good illustration of different phytomolecules (flavonoids, organic acids and selenocompounds), presents in leaves of the five traditional medicinal plants endemic to Macaronesia, all exhibiting antioxidant propertiesinfo:eu-repo/semantics/publishedVersio