Search

Introgression breeding represents a useful method for generating new germplasm resources which combine positive attributes from different species. Within forage grasses, the interfertility of Lolium and Festuca spp. represents a viable route for achieving this end. In order to evaluate the architecture of trait inheritance within this introgression context, a complete chromosome introgression series of F. pratensis (Fp; meadow fescue) in the L. perenne (Lp; perennial ryegrass) background, and derived progeny, were evaluated for shoot and root biomass and N and P uptake in a hydroponic experiment. The results indicated that the Fp parent and the monosomic introgressions relating to Fp chromosomes 3 and 4 showed enhanced shoot and root biomass. However, there was no clear relationship between these phenotypes of the Fp chromosome 3 and 4 monosomic introgressions and that of their derived, respective, progenies. Thus, the interaction between the Lp and Fp genomes in determining phenotype is likely to be complex.

International audience; The choice of cultivation system in arable agriculture exerts a strong influence not only on soil health and crop productivity but also on the wider environment. Conservation tillage using non-inversion methods conserves soil carbon, reduces erosion risk and enhances soil quality. In addition, conservation tillage has been shown to sequester more carbon within the soil than inversion tillage, reducing carbon dioxide losses to the atmosphere. Stable, well structured topsoils that develop following long-term conservation tillage lead to more energy efficient systems due to the reduced power requirements for cultivation. Long-term experiments, e.g. more than 20 years, that confirm the impact of conservation tillage over an extended period are not common. Here we evaluate the impact of different tillage methods and winter wheat straw management, either incorporated or removed, on organic matter turnover and soil quality indicators. No-till, chisel and mouldboard ploughing was carried out for 23 years on a silty clay loam soil in South West England that was not considered suitable for non-inversion tillage due to weak soil structure. In order to assess the effect of contrasting cultivation and straw disposal method on soil carbon dynamics, a range of assays were conducted, including water extractable organic carbon, hot water extractable carbohydrate, microbial biomass carbon, activity of β-glucosidase and acid phosphatase enzymes, C sequestration and the natural abundance of 13 C. Our results show that the soil organic carbon concentration in the topsoil was greater under no-till than mouldboard ploughing, while a reverse trend was observed in the lower depths. A 14-17% increase in soil organic carbon was observed in the topsoil for chisel plough and no-till treatments compared to mouldboard ploughing. Water extractable organic carbon was found to constitute only 1-7% of the microbial biomass carbon. Hot water extractable carbohydrate was one of the most sensitive indicators of soil quality and had a significant a negative correlation with bulk density and positive correlation with soil organic carbon microbial biomass carbon β-glucosidase and acid phosphatase. The choice of cultivation method exerted a major control on microbial and carbon dynamics. No-till and chisel ploughing maintained carbon in the soil surface horizons, which will benefit the stability of this weakly structured soil, but mouldboard ploughing distributed carbon more uniformly throughout the soil profile, particularly when straw was incorporated, hence leading to the retention of more carbon in the soil profile.

We investigated the specific diet and habitat of earthworms in relation to land use changes by integrating spatial and temporal scales and by using stable isotope (13C and 15N) techniques. The study involved two sites: Santiago (Northwest Spain) and North Wyke (Southwest England), both consisting of long term grassland which was partly converted to a maize crop in 1997. In 1998, the maize crop in Spain was divided into two, and one half was re-planted with maize (2 years maize) and the other half reconverted to grassland (1 year grassland); the same procedure was followed for the grassland resulting in two treatments, 2 years grassland and 1 year maize. At the English site only 2 years maize and 2 years grassland were under investigation. Within each of the four treatments in Spain and the two in England, three replicate plots were established. Random soil samples from three different depths (0–10, 10–20 and 20–30 cm), and earthworm specimens belonging to four different ecological categories (epigeic, anecic, epi/anecic and endogeic), were taken from each plot, treatment and site at the peak of the maize growth and after harvesting. Spanish soils were 13C-enriched and 15N-depleted when compared to the English ones, which was also reflected in the earthworm tissue, and allowed a direct relationship between the delta values of the animals and the cropping treatments. The enrichment in the 13C values of the worms feeding on the maize (C4) plots, when compared to those found under the grassland (C3) plots, was greater than the difference detected in the C4 vs C3 soils. This result clearly indicates selective feeding by earthworms with a preference for fresh C4 residue over older native C3. Different ecological and age groups appeared to consume organic material of differing quality, with endogeic species and mature worms showing the highest N isotope values as a result of preferential feeding in deeper soil profiles. This information proves that combined C and N isotope analysis constitutes a powerful tool in studying feeding ecology and emphasises the need for long-term studies which incorporate spatial and temporal scales to the experimental set-up.

The rate and depth of cattle dung incorporation into moorland soil may be an important factor influencing plant community dynamics through its effects on soil nutrient availability. This study traces the incorporation of (15)N-labelled dung into a moorland soil under two vegetation types in Dartmoor National Park, UK. Cores of treated and control soil 10 cm deep were collected at 2, 4, 8 and 16 week intervals and divided into 2 cm depth increments. Soil samples were freeze-dried, ground and analysed for atom% (15)N and %N content using continuous-flow isotope-ratio mass spectrometry. The contribution of dung N to the soil N pool was estimated by changes in atom% (15)N of the soil. The incorporation of dung dry matter into the soil was also calculated. The labile component of the dung N was incorporated deeper and more rapidly into soil under grass than under heather vegetation. The implications of these processes for the dynamics of upland plant communities are considered in relation to the ability of plants to compete for nutrients.

The composition of dissolved organic matter (DOM) in a soil is the product of a variety of soil processes. Changes in the composition of DOM in water discharged from soil should, therefore, give an important insight into modifications in these soil processes. We hypothesise that these processes in soils, under different grassland management regimes, would be affected to different extents by the short-term disturbance of a storm event and that evidence of this could be detected in delta(13)C and delta(15)N signatures in drainage and surface runoff waters. During a storm event we collected discharge waters from 1 ha grassland lysimeters, with or without artificial drainage, which received contrasting fertiliser inputs, and delta(13)C and delta(15)N signatures were determined. Changes in (13)C enrichment during the storm event were clearly identifiable, as were differences between plots for (13)C and (15)N, illustrating that this technique has potential to be a useful tool for identifying and investigating short- and long-term changes in soil organic matter dynamics. Copyright 1999 John Wiley & Sons, Ltd.

Changes in the specific diet of earthworms with time in relation to landuse changes and two different climates were studied by analysing (13)C and (15)N natural abundance in soils and animals. Soil samples from three depths (0-10, 10-20 and 20-30 cm) and earthworms were collected from two sites: Santiago (Northwest Spain) and North Wyke (Southwest England) both consisting of replicated long-term grasslands and recently converted to maize plots. Earthworms were hand-sorted in the field at the peak of the maize growth and after harvesting at both sites. In the Spanish plots, nine and eight earthworm species, all belonging to the three ecological categories (epigeic, anecic and endogeic), were found under maize and permanent pasture, whereas at the English site five and seven different species were, respectively, identified. At both sites (13)C isotopic values of the earthworm tissues reflected changes in diet from C(3) to C(4) with epigeic and epi/anecic worms in the maize plots showing one delta unit difference in relation to the ones found in the grassland plots. Anecic worms seemed to be less responsive to landuse changes. The higher (13)C values of the Spanish soils were also reflected in the earthworm tissues when compared with the English samples. (15)N values showed no clear relationship with the cropping treatments but were clearly related to the ecological grouping, with endogeic worms reaching the highest values whereas for the epigeic and epi/anecic species the lowest values were obtained. This finding was also previously recorded by other authors1 and suggests that, in the future, stable isotope techniques could also be a useful tool in taxonomic studies. Copyright 1999 John Wiley & Sons, Ltd.

Leaf elongation rate (LER) is a key component of forage grass dry matter yield. Leaf lamina initiate rapid expansion during the winter at a time that coincides with lengthening days but this extension is not associated with any large environmental shifts such as an increase in light intensity or temperature. The rate increase precedes any anatomical indication of floral initiation in apical meristems (double ridge formation) by around 2–3 weeks. We measured LER in a perennial ryegrass (Lolium perenne L.) pair-cross mapping family that has been extensively mapped with more than 1,200 SNP markers generated by Illumina’s Infinium platform. These have been anchored to the seven Lolium linkage groups as defined by Triticeae nomenclature with seven micro-satellite markers originally developed by ViaLactia Biosciences. Measurements were made in the winter/spring during extending day length, after full natural vernalisation. The plants’ leaves were beginning to expand rapidly with leaf extension rates varying between approximately 0.4 mm and 1.1 mm h−1. We obtained a significant correlation between LER and both apical meristem elongation and ear emergence (the date at which inflorescences emerge above the flag-leaf ligule) measured in two separate seasons. A QTL for LER was revealed with a peak some distance away from the major floral initiation and ear emergence date QTL on linkage group 7. This is the first evidence of genetic linkage that determines the often observed association between LER in herbage grasses in the spring with floral initiation determined in large part by the action of Arabidopsis flowering initiation gene homologues, Flowering Time Locus (FT) and Constans (CO).

Many Higher Education Institutions (HEIs) in the UK are developing Information Strategies. Paradoxically, there is no consensus over terminology and concepts surrounding the issue. Very little research has been conducted in this area and this is reflected in the dearth of literature available on the subject, both practitioner and theoretical. As part of an ongoing research project in the Department of Information Studies at Sheffield University a survey was sent out to four stakeholders in 192 Higher Education Institutions in the UK. The aim of this survey was to explore process, content and use of the two intertwined concepts of Information Strategies and Information Technology (IT) Strategies. This paper focuses upon the data from the survey that illuminate issues relating to the success or failure of IT strategies developed in HEIs and the extent to which this can inform the present Information Strategy formulation process. The following issues are discussed in this context: Ownership, Motivation, Lead...

Carbon sequestration in the soil profile depends on a number of soil, plant, climatic and management factors, and their interactions. Plants affect the quantity, quality and placement of carbon in the soil profile. Ecological studies have demonstrated considerable variation in soil organic matter (SOM) under different types of grassland but the potential for exploiting genetic variation amongst grasses for carbon deposition in the soil has not yet been explored. Neither has there been any attempt to select and breed amenity or forage grass genotypes exhibiting enhanced carbon sequestration.

The rate and depth of cattle dung incorporation into moorland soil may be an important factor influencing plant community dynamics through its effects on soil nutrient availability. This study traces the incorporation of (15)N-labelled dung into a moorland soil under two vegetation types in Dartmoor National Park, UK. Cores of treated and control soil 10 cm deep were collected at 2, 4, 8 and 16 week intervals and divided into 2 cm depth increments. Soil samples were freeze-dried, ground and analysed for atom% (15)N and %N content using continuous-flow isotope-ratio mass spectrometry. The contribution of dung N to the soil N pool was estimated by changes in atom% (15)N of the soil. The incorporation of dung dry matter into the soil was also calculated. The labile component of the dung N was incorporated deeper and more rapidly into soil under grass than under heather vegetation. The implications of these processes for the dynamics of upland plant communities are considered in relation to the ability of plants to compete for nutrients.

Thirty male weanling Sprague-Dawley rats were fed either a copper deficient diet (0.85 mg Cu/kg) or a copper-adequate diet (8 mg Cu/kg). After 7 weeks, the rats were fasted for 12 hours, and injected intravenously with thyrotropin-releasing hormone (TRH, 30 ng/100 g body weight). Six rats from each treatment were killed at 0, 0.5, 1, 2 and 4 hours after TRH injection. Sera obtained at 0, 0.5 and 1 hour, and at 0.2 and 4 hours were used for the radioimmunoassay of thyroid-stimulating hormone (TSH) and thyroxine (T4), respectively. Reduction in liver copper content confirmed that the rats fed the test diet were copper-deficient. Serum TSH levels appeared to have peaked at 30 minutes but declined to a level higher than basal at 1 hour. No difference in TSH response was observed between the 2 treatments. Serum T4 response to TRH was reduced in the copper-deficient as compared to the adequate rats at all time intervals. After 2 hours a slight elevation was observed in the controls, but marked elevations in T4 were observed in both treatments at 4 hours. This reduction in T4 levels could be due to an impaired T4 synthesis or release in copper-deficient rats.