Cutting regime determines allocation of fixed nitrogen in white clover

Leguminous leys are important sources of nitrogen (N), especially in forage-based animal production and organic cropping. Models for estimating total N₂ fixation of leys—including below-ground plant-derived N (BGN)—are based on grazed or harvested leys. However, green manure leys can have different proportions of above-ground plant-derived N (AGN) and BGN when subjected to different cutting regimes. To investigate the effects of cutting on N distribution in white clover, a pot experiment was carried out using ¹⁵N techniques to determine N₂ fixation, N rhizodeposition and root C and N content of cut and uncut white clover (Trifolium repens L. cv. Ramona) plants. Percentage N derived from air (%Ndfa) was lower in uncut (63%) than in cut (72%) plants, but total Ndfa was not significantly affected by cutting. The higher reliance on N₂ fixation in cut plants was thus counterbalanced by lower biomass and total N content. With BGN taken into account, total plant-derived N increased by approximately 50% compared with AGN only. Cutting did not affect the proportion of BGN to standing shoot biomass N after regrowth, but decreased the proportion of BGN to total shoot biomass production during the entire growth period. Thus, estimates of N fixation in green manure leys should consider management practices such as cutting regime, as this can result in differences in above- and below-ground proportions of plant-derived N.     

Modelling of the effect of dry periods on yielding of spring barley

The paper presents a weather-yield model developed for the purpose of estimating spring barley yield on the basis of dry spells occurring in individual periods between the phenological phases of that plant. For that purpose research material on spring barley, originating from the years 1976-1997, was used as well as diurnal sums of precipitation. Five periods were considered in the analysis: sowing-emergence, emergence-tillering, tillering-heading, heading-milk ripeness and milk ripeness-full ripeness. In the study a model of changes in the amount of water available for plant during rainless periods was used. Five measures were adopted for characterisation of the approximation error: correlation coefficient, mean relative error, relative root mean square error, model efficiency and coefficient of residual mass. The analyses performed demonstrated that yield reduction is significantly influenced by rainless periods that occur in the sowing-emergence and tillering-heading inter-phase periods. The adopted criteria for yield reduction estimation show considerable similarity for the emergence-tillering and heading-milk ripeness inter-phase periods. At the same time, their influence on yield reduction is three-fold lower than during the sowing-emergence and tillering-heading inter-phase periods. Analyses performed with the use of the developed model indicate that yield size is affected by rainless periods of duration longer than 30% of the inter-phase period.     

Different crop rotation systems as drivers of change in soil bacterial community structure and yield of rice, <Emphasis Type="Italic">Oryza sativa</Emphasis>

Intensive cropping, especially of rice, is considered to contribute to negative effects not only on soil chemical and biological properties but also on long-term grain yield. Appropriate crop rotation is often practiced as an alternative strategy to overcome the negative side effects of intensive cropping. Although soil microbial diversity and community structure have been shown to respond differently to altered agricultural management practices, little is known about possible links between crop rotation and grain yield on bacterial communities in rice paddy soil. In this study, we investigated the impact of specific rotational crops and compared it with intensive rice cultivation. The main crop rice (Oryza sativa) was rotated with maize (Zea mays) and mungbean (Phaseolus aureus) in different combinations in a system cultivating three crops per year. Soil bacterial communities were studied in two different cropping periods using pyrosequencing of the variable V4 region of the 16S rRNA. Our results showed that rotation with alternative crops increased rice yield by 24–46% depending on rotation structure and that bacterial community structure was altered in the presence of mungbean and/or maize compared to that in rice monoculture. In the crop rotation systems, composition, abundance, and diversity of soil bacterial communities were significantly different and higher than those in rice monoculture. Our results show that effects of crop rotation relate to changes in soil bacterial community structure suggesting that appropriate crop rotations provide a feasible practice to maintain the equilibrium in soil microbial environment for sustainable rice cultivation.     

Forms of trace metals from inorganic sources in soils and amounts found in spring barley

Barley (Hordeum vulgare L.) was grown on a sandy soil given different doses of cadmium carbonate (salt), copper carbonate (malachite), lead carbonate (cerussite), and zinc carbonate (smithsonite) in a pot experiment conducted in a greenhouse. The element compounds were added to the soil in amounts equivalent to the following levels of the metals: Cd 5, 10, 50 μq ^?1; Cu and Pb 50, 100, 500 μg g^?1; Zn 150, 300, 1500 μg g^?1. Sequential extraction was used for partition these metals into five operationally-defined fractions: exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter and residual. The residue was the most abundant fraction in the untreated soil for all the metals studied (43 to 61% of the total contents). The concentration of exchangeable Cd (0.2 μg g^?1), Cu (0.01 μg g^?1), Pb (0.1 μg g^?1), and Zn (1.4 μg g^?1) were relatively low in the untreated soil but increased markedly in the treated soils for Cd (up to 31 μg g^?1) and Zn (up to 83 μg g^?1), whereas only small changes were observed for Cu and Pb. The pot experiment showed a significant increase in the Cd and Zn contents of barley grown on the treated soils, but only small changes in Cu and Pb concentrations.     

Cardiorespiratory effects of a 7° reverse Trendelenburg position in anaesthetized horses: a randomized clinical trial

Objective

To evaluate the cardiorespiratory effects of a 7° reverse Trendelenburg position (RTP) in anaesthetized horses.

ADP ribosylation factor regulates metabolism and antioxidant capacity of transgenic potato tubers

In our recent studies we have evidenced that repression of ADP-ribosylation factor (ARF) in potato plants results in 14-3-3 gene activation. The significant alteration in plant phenotype and in carbohydrate content clearly indicates that there may also be changes in other metabolite syntheses. In this paper we present the data on contents of compounds, occurring in transgenic potato tubers from field trial, known to be important for the human diet. We also determine which of the ARF-antisense plant features resulted from ARF repression. This determination was accomplished by the analysis of ARF-antisense plants transformed with cDNA encoding 14-3-3 protein in reverse orientation. The sucrose accumulation and the decrease in glycoalkaloids level were found to be characteristic features of all transgenic plants. The increase in antioxidant capacity of transgenic potato tubers should also be pointed out. The analysis of fat from modified potato tubers revealed a nutritionally valuable composition of fatty acids, including the significant increase of linoleic acid level.     

Composition of organic C fractions in soils of different texture affected by sugarcane monoculture

ABSTRACT

Sugarcane is a strategic commodity in Indonesia. It is usually raised in a monoculture system. There is a lack of information about the effects of extended sugarcane monoculture on the soil carbon fraction. The aim of this study was to determine the relative changes in the soil organic C fractions in response to the duration of sugarcane monoculture on Entisols, Inceptisols, and Vertisols. The measured variables were the percentages of sand, silt, and clay, organic matter (OM), total nitrogen (TN), pH (H₂O), cation exchange capacity (CEC), NH₄ ⁺, NO₃ ^-, labile carbon fraction (soil carbon mineralization (C-Min), soil microbial carbon (C-Mic), and carbon particulate organic matter (C-POM)), and stable carbon fraction (humic and fulvic acids). Soil type with sugarcane monoculture period had significant influences on the percentages of clay, sand, silt, CEC, and pH (H₂O). Soil type and sugarcane monoculture period had no apparent significant effect on C-Min or C-POM but did significantly influence C-Mic. The humic and fulvic acid levels in all three soil types were affected by the duration of sugarcane monoculture. To establish the impact of long-term sugarcane monoculture on the physicochemical properties of soils with various textures, it is more appropriate to measure the soil stable carbon fractions such as humic and fulvic acid rather than the soil labile carbon fractions such as C-Min, C-POM, or C-Mic.     

Use of space by bank voles (Clethrionomys glareolus) in a polish farm landscape

Movements of bank voles (Clethrionomys glareolus) were studied in a farmland mosaic in Poland. Distances crossed by animals in short-time periods are significantly longer in heterogenous than in homogenous habitats. In long-time and large-spatial scales, a significant portion of the animals in a population travel among habitat elements of the mosaic, reducing the degree of isolation of patch populations and decreasing the probability of local extinction.     

A rare Cryptosporidium parvum genotype associated with infection of lambs and zoonotic transmission in Italy

An outbreak of cryptosporidiosis occurred in a mixed sheep/cattle farm of Central Italy in October 2011. A total of 450 ovines (250 sheep and 200 lambs) and 140 bovines (130 cows and 10 calves) were housed in two separated units, at the time of the outbreak. About half of the lambs had diarrhea due to Cryptosporidium sp. with a mortality rate of 80%; calves were not infected. Genomic DNA was extracted from an archived slide and from fecal specimens, and the parasite was identified as Cryptosporidium parvum by PCR and sequence analysis at the CpA135 gene. Genotyping at the GP60 gene showed the presence of a very rare genotype, IIaA20G2R1. Shortly after the outbreak was identified, the son of the farm's owner, aged 18 months, experienced an acute gastroenteritis and was hospitalized due to recurrent episodes of diarrhea, fever, vomiting and lack of appetite. The feces tested negative for bacteria and viruses, whereas cryptosporidiosis was diagnosed by microscopy and an immunochromatographic test. Molecular typing identified the C. parvum genotype IIaA20G2R1 in the feces of the child. This is the first case of transmission of cryptosporidiosis in Italy involving lambs as source of oocysts infectious to humans.