PGR forum: serving the crop wild relative user community

The Euro-Mediterranean region is an important centre for the diversity of crop wild relatives. Crops, such as oats (Avena sativa), sugar beet (Beta vulgaris), apple (Malus domestica), annual meadow grass (Festuca pratensis), white clover (Trifolium repens), arnica (Arnica montana), asparagus (Asparagus officinalis), lettuce (Lactuca sativa), and sage (Salvia officinalis) etc., all have wild relatives in the region. The European Community funded project, PGR Forum (www.pgrforum.org) is building an online information system to provide access to crop wild relative data to a broad user community; including plant breeders, protected area managers, policy-makers, conservationists, taxonomists and the wider public. The system will include data on uses, geographical distribution, biology, population and habitat information, threats (including IUCN Red List assessments) and conservation actions. This information is vital for the continued sustainable utilisation and conservation of crop wild relatives. Two major databases have been utilised as the backbone to a Euro-Mediterranean crop wild relative catalogue, which forms the core of the information system: Euro+Med PlantBase (www.euromed.org.uk) and Mansfeld’s World Database of Agricultural and Horticultural Crops (http://mansfeld.ipk-gatersleben.de). By matching the genera found within the two databases, a preliminary list of crop wild relatives has been produced. Around 20,000 of the 30,000+ species listed in Euro+Med PlantBase can be considered crop wild relatives, i.e. those species found within the same genus as a crop. The list is currently being refined by implementing a priority ranking system based on the degree of relatedness of taxa to the associated crop.

Can the study of natural vegetation succession assist in the control of soil erosion on abandoned croplands on the Loess Plateau, China?

In the Loess Plateau, China, arable cultivation of slope lands is common and associated with serious soil erosion. Planting trees or grass may control erosion, but planted species may consume more soil water and can threaten long-term ecosystem sustainability. Natural vegetation succession is an alternative ecological solution to restore degraded land, but there is a time cost, given that the establishment of natural vegetation, adequate to prevent soil erosion, is a longer process than planting. The aims of this study were to identify the environmental factors controlling the type of vegetation established on abandoned cropland and to identify candidate species that might be sown soon after abandonment to accelerate vegetation succession and establishment of natural vegetation to prevent soil erosion. A field survey of thirty-three 2 × 2–m plots was carried out in July 2003, recording age since abandonment, vegetation cover, and frequency of species together with major environmental and soil variables. Data were analyzed using correspondence analysis, classification tree analysis, and species response curves. Four vegetation types were identified and the data analysis confirmed the importance of time since abandonment, total P, and soil water in controlling the type of vegetation established. Among the dominant species in the three late-successional vegetation types, the most appropriate candidates for accelerating and directing vegetation succession were King Ranch bluestem (Bothriochloa ischaemum) and Lespedeza davurica (Leguminosae). These species possess combinations of the following characteristics: tolerance of low water and nutrient availability, fibrous root system and strong lateral vegetative spread, and a persistent seed bank.

Vertical distribution, size and composition of the weed seedbank under various tillage and herbicide treatments in a sequence of industrial crops

Investigations were conducted during the 2003, 2004 and 2005 growing seasons in northern Greece to evaluate effects of tillage regime (mouldboard plough, chisel plough and rotary tiller), cropping sequence (continuous cotton, cotton-sugar beet rotation and continuous tobacco) and herbicide treatment on weed seedbank dynamics. Amaranthus spp. and Portulaca oleracea were the most abundant species, ranging from 76% to 89% of total weed seeds found in 0-15 and 15-30 cm soil depths during the 3 years. With the mouldboard plough, 48% and 52% of the weed seedbank was found in the 0-15 and 15-30 cm soil horizons, while approximately 60% was concentrated in the upper 15 cm soil horizon for chisel plough and rotary tillage. Mouldboard ploughing significantly buried more Echinochloa crus-galli seeds in the 15-30 cm soil horizon compared with the other tillage regimes. Total seedbank (0-30 cm) of P. oleracea was significantly reduced in cotton-sugar beet rotation compared with cotton and tobacco monocultures, while the opposite occurred for E. crus-galli. Total seed densities of most annual broad-leaved weed species (Amaranthus spp., P. oleracea, Solanum nigrum) and E. crus-galli were lower in herbicide treated than in untreated plots. The results suggest that in light textured soils, conventional tillage with herbicide use gradually reduces seed density of small seeded weed species in the top 15 cm over several years. In contrast, crop rotation with the early established sugar beet favours spring-germinating grass weed species, but also prevents establishment of summer-germinating weed species by the early developing crop canopy.

Predicting the functional response of a farmland bird

1. Mechanistic models may be able to predict how changes in agricultural practice influence farmland bird populations. A key component of these models is the link between food and competitor densities and the rate at which birds consume food, i.e. the functional response. 2. This paper tests whether the functional response of a farmland bird, the rook Corvus frugilegus, can be predicted from three parameters: searching speed, food detection distance and handling time. It is often difficult to measure the functional response of farmland birds directly, but it may be possible to measure behavioural parameters more quickly. 3. We performed experiments in which rooks fed on a range of artificial food densities in two grass sward heights. Food detection distance was greater in the shorter sward, but sward height did not influence searching speed or handling time. The functional response could be accurately predicted in both sward heights. 4. We show that the functional response of a farmland bird can be predicted from parameters that can be measured more quickly than the alternative of measuring the functional response directly. This implies that the functional responses of other farmland birds may be predicted using a minimum of information.

Combining competition from Lolium perenne and an insect-fungus combination to control Rumex obtusifolius seedlings

Although adult Rumex obtusifolius are problematic weeds, their seedlings are poor competitors against Lolium perenne, particularly in established swards. We investigated the possibility of using this weakness to augment control of R. obtusifolius seedlings with combinations of Gastrophysa viridula (Coleoptera: Chrysomelidae) and the rust fungus Uromyces rumicis. Rumex obtusifolius seedlings were grown in competition with L. perenne sown at different rates and times after R. obtusifolius: they competed successfully with L. perenne when sown 21 days before the grass. Sowing both species at the same time resulted in a dominant grass sward, with R. obtusifolius becoming dominant when sown 42 days prior to L. perenne. Grass sowing rate had no effect on R. obtusifolius growth or biomass. A second experiment investigated how competition from L. perenne sown 21 days after R. obtusifolius combined with damage from G. viridula and/or U. rumicis (applied at either the 3-4- or 10-13-leaf stage, or at both stages) affected the growth and final biomass of R. obtusifolius. Beetle grazing at the latter leaf stage was the only treatment that reduced R. obtusifolius biomass, although rust infection at the earlier application led to an increase in shoot and root weight. The results are discussed in terms of the potential for use of these agents in the field.

Interactions between the grasses Phalaris arundinacea, Miscanthus sinensis and Echinochloa crus-galli, and barley and cereal yellow dwarf virusus

The grass species Miscanthus sinensis, Echinochloa crus-galli and Phalaris arundinacea may be useful biomass crops. In glasshouse inoculations with two isolates of Barley yellow dwarf virus (BYDV)-MAV and BYDV-PAV and one of Cereal yellow dwarf virus (CYVD)-RPV , E. crus galli was infected by all three virus isolates, P. arundinacea by BYDV-MAV and CYDV-RPV, but M. sinensis only by BYDV-MAV. All three hosts became very difficult to infect after several weeks’ growth. Symptoms were inconspicuous; dry matter yield losses ranged from c. 20–40%. Aphids acquired all three virus isolates from E. crus-galli, but more efficiently from 5 than 26-week-old plants. Only BYDV-MAV was acquired from P. arundinacea and M. sinensis. Plants of each species and of Avena sativa were grown outdoors between May and July in 1994 and 1995. Young plants of each species were exposed for successive 2-week intervals during the same periods. Vector populations were higher on A. sativa and P. arundinacea than on E. crus-galli and M. sinensis, and more plants of these species became infected. In 1994 only BYDV-MAV was detected. In 1995 BYDV-MAV, BYDV-PAV and CYDV-RPV were all detected; BYDV-MAV was again the virus isolate most frequently found.

Effect of forage type and proportion of concentrate in the diet on milk fatty acid composition in cows given sunflower oil and fish oil

Based on the potential benefits of cis-9, trans- 11 conjugated linoleic acid (CLA) for human health there is a need to develop effective strategies for enhancing milk fat CLA concentrations. In this experiment, the effect of forage type and level of concentrate in the diet on milk fatty acid composition was examined in cows given a mixture of fish oil and sunflower oil. Four late lactation Holstein-British Friesian cows were used in a 4 x 4 Latin-square experiment with a 2 x 2 factorial arrangement of treatments and 21-day experimental periods. Treatments consisted of grass (G) or maize (M) silage supplemented with low (L) or high (H) levels of concentrates (65: 35 and 35: 65; forage: concentrate ratio, on a dry matter (DM) basis, respectively) offered as a total mixed ration at a restricted level of intake (20 kg DM per day). Lipid supplements (30 g/kg DM) containing fish oil and sunflower oil (2: 3 w/w) were offered during the last 14 days of each experimental period. Treatments had no effect on total DM intake, milk yield, milk constituent output or milk fat content, but milk protein concentrations were lower (P<0.05) for G than M diets (mean 43.0 and 47.3 g/kg, respectively). Compared with grass silage, milk fat contained higher (P<0.05) amounts Of C-12: 0, C-14: 0, trans C-18:1 and long chain >= C20 (n-3) polyunsaturated fatty acids (PUFA) and lower (P<0.05) levels Of C-18:0 and trans C-18:2 when maize silage was offered. Increases in the proportion of concentrate in the diet elevated (P<0.05) C-18:2 (n-6) and long chain >= C20 (n-3) PUFA content, but reduced (P<0.05) the amount Of C-18:3 (n-3). Concentrations of trans-11 C-18:1 in milk were independent of forage type, but tended (P<0.10) to be lower for high concentrate diets (mean 7.2 and 4.0 g/100 g fatty acids, for L and H respectively). Concentrations of trans-10 C-18:1 were higher (P<0.05) in milk from maize compared with grass silage (mean 10.3 and 4.1 g/100 g fatty acids, respectively) and increased in response to high levels of concentrates in the diet (mean 4.1 and 10.3 g/100 g fatty acids, for L and H, respectively). Forage type had no effect (P>0.05) on total milk conjugated linoleic acid (CLA) (2.7 and 2.8 g/100 g fatty acids, for M and G, respectively) or cis-9, trans-11 CLA content (2.2 and 2.4 g/100 g fatty acids). Feeding high concentrate diets tended (P<0.10) to decrease total CLA (3.3 and 2.2 g/100 g fatty acids, for L and H, respectively) and cis-9, trans-11 CLA (2.9 and 1/7 g/100 g fatty acids) concentrations and increase milk trans-9, cis-11 CLA and trans-10, cis-12 CLA content. In conclusion, the basal diet is an important determinant of milk fatty acid composition when a supplement of fish oil and sunflower oil is given.

Effect of dietary fish oil on biohydrogenation of fatty acids and milk fatty acid content in cows

Mechanisms underlying milk fat conjugated linoleic acid (CLA) responses to supplements of fish oil were investigated using five lactating cows each fitted with a rumen cannula in a simple experiment consisting of two consecutive 14-day experimental periods. During the first period cows were offered 18 kg dry matter (DM) per day of a basal (B) diet formulated from grass silage and a cereal based-concentrate (0.6 : 0.4; forage : concentrate ratio, on a DM basis) followed by the same diet supplemented with 250 g fish oil per day (FO) in the second period. The flow of non-esterified fatty acids leaving the rumen was measured using the omasal sampling technique in combination with a triple indigestible marker method based on Li-Co-EDTA, Yb-acetate and Cr-mordanted straw. Fish oil decreased DM intake and milk yield, but had no effect on milk constituent content. Milk fat trans-11C(18:1), total trans-C-18:1, cis-9 trans-11 CLA, total CLA, C-18 :2 (n- 6) and total C-18:2 content were increased in response to fish oil from 1.80, 4.51, 0.39, 0. 56, 0.90 and 1.41 to 9.39, 14.39, 1.66, 1.85, 1.25 and 4.00 g/100 g total fatty acids, respectively. Increases in the cis-9, trans-11 isomer accounted for proportionately 0.89 of the CLA response to fish oil. Furthermore, fish oil decreased the flow of C-18:0 (283 and 47 g/day for B and FO, respectively) and increased that of trans-C-18:1 fatty acids entering the omasal canal (38 and 182 g/day). Omasal flows of trans-C-18:1 acids with double bonds in positions from delta-4 to -15 inclusive were enhanced, but the effects were isomer dependent and primarily associated with an increase in trans-11C(18:1) leaving the rumen (17.1 and 121.1 g/day for B and FO, respectively). Fish oil had no effect on total (4.36 and 3.50 g/day) or cis-9, trans-11 CLA (2.86 and 2.08 g/day) entering the omasal canal. Flows of cis-9, trans-11 CLA were lower than the secretion of this isomer in milk. Comparison with the transfer of the trans-9, trans-11 isomer synthesized in the rumen suggested that proportionately 0.66 and 0.97 of cis-9, trans-11 CLA was derived from endogenous conversion of trans-11 C-18:1 in the mammary gland for B and FO, respectively. It is concluded that fish oil enhances milk fat cis-9, trans-11 CLA content in response to increased supply of trans-11 C-18:1 that arises from an inhibition of trans C-18:1 reduction in the rumen.

Water-soluble precursors of beef flavour I: effect of diet and breed

The effects of diet and breed on the concentration of water-soluble flavour precursors, namely sugars, free amino acids, ribonucleotides, creatinine, carnosine and creatine, were studied in beef longissimus hanborum muscle. Diet had a significant effect on the concentration of free amino acids, with animals fed on grass silage having higher free amino acid levels than animals fed on a concentrate diet, whereas animals fed concentrates had a higher total reducing sugar content. Differences between a beef breed (Aberdeen Angus x Holstein-Friesian) and a dairy breed (Holstein-Friesian) were generally small. (C) 2007 Elsevier Ltd. All rights reserved.

A comparison of the aroma volatiles and fatty acid compositions of grilled beef muscle from Aberdeen Angus and Holstein-Friesian steers fed diets based on silage or concentrates

This paper compares the volatile compound and fatty acid compositions of grilled beef from Aberdeen Angus and Holstein-Friesian steers slaughtered at 14 months, each breed fed from 6 months on either cereal-based concentrates or grass silage. Linoleic acid levels were higher in the muscle of concentrates-fed animals, which in the cooked meat resulted in increased levels of several compounds formed from linoleic acid decomposition. Levels of alpha-linolenic acid, and hence some volatile compounds derived from this fatty acid, were higher in the meat from the silage-fed steers. 1-Octen-3-ol, hexanal, 2-pentylfuran, trimethylamine, cis- and trans-2-octene and 4,5-dimethyl-2-pentyl-3-oxazoline were over 3 times higher in the steaks from the concentrates-fed steers, while grass-derived 1-phytene was present at much higher levels in the beef from the silage-fed steers. Only slight effects of breed were observed. (C) 2004 Elsevier Ltd. All rights reserved.

The effects of diet, breed and age of animal at slaughter on the aroma compounds of grilled beef

The aroma volatiles of grilled beef, from animals fed either grass silage or cereal concentrates, were compared. Aberdeen Angus and Holstein-Friesian cross-breed steers, slaughtered at 14 or 24 months, were studied. Compounds formed from linoleic acid, in particular 2-pentylfuran, 1-octen-3-ol, (Z)-2-octen-1-ol, and hexanal were at higher levels in the meat from the animals fed concentrates. Phytenes and compounds formed from α-linolenic acid, in particular 1-penten-3-ol and (Z)-2-penten-1-ol, were at higher levels in the meat of animals fed silage. Differences due to breed were small and not consistent with slaughter age. Dimethyl disulfide, dimethyl disulfide and phenol were at higher levels in the meat of animals slaughtered at 24 months and may contribute to grilled beef aroma.

Optimization algorithms in FMRF model-based segmentation for LIDAR data and co-registered bands

In this paper, a fuzzy Markov random field (FMRF) model is used to segment land-objects into free, grass, building, and road regions by fusing remotely, sensed LIDAR data and co-registered color bands, i.e. scanned aerial color (RGB) photo and near infra-red (NIR) photo. An FMRF model is defined as a Markov random field (MRF) model in a fuzzy domain. Three optimization algorithms in the FMRF model, i.e. Lagrange multiplier (LM), iterated conditional mode (ICM), and simulated annealing (SA), are compared with respect to the computational cost and segmentation accuracy. The results have shown that the FMRF model-based ICM algorithm balances the computational cost and segmentation accuracy in land-cover segmentation from LIDAR data and co-registered bands.

Gene transcription in Daphnia magna: effects of acute exposure to a carbamate insecticide and an acetanilide herbicide.

Daphnia magna is a key invertebrate in the freshwater environment and is used widely as a model in ecotoxicological measurements and risk assessment. Understanding the genomic responses of D. magna to chemical challenges will be of value to regulatory authorities worldwide. Here we exposed D. magna to the insecticide methomyl and the herbicide propanil to compare phenotypic effects with changes in mRNA expression levels. Both pesticides are found in drainage ditches and surface water bodies standing adjacent to crops. Methomyl, a carbamate insecticide widely used in agriculture, inhibits acetylcholinesterase, a key enzyme in nerve transmission. Propanil, an acetanilide herbicide, is used to control grass and broad-leaf weeds. The phenotypic effects of single doses of each chemical were evaluated using a standard immobilisation assay. Immobilisation was linked to global mRNA expression levels using the previously estimated 48h-EC(1)s, followed by hybridization to a cDNA microarray with more than 13,000 redundant cDNA clones representing >5000 unique genes. Following exposure to methomyl and propanil, differential expression was found for 624 and 551 cDNAs, respectively (one-way ANOVA with Bonferroni correction, P

Farming and food production and development in the Shropshire Hills Environmentally Sensitive Area, 1997-2008

European agricultural and environmental policy has evolved considerably over the last 15 years. In this paper the changes in farm businesses in an Environmentally Sensitive Area in England are evaluated based on two surveys with the same farmers at the start and end of this period. The rate of participation in the environmental scheme had increased significantly at a time when Government led goals in this area had developed and become more output focussed. A combination of policy, market and animal health status changes had encouraged a number to leave cattle production, and though remaining with stock and grass they had decided against any extensive development in the direction of pluriactivity – with or without Government encouragement. This left the future of this group in some uncertainty given that two significant forms of financial support, the environmental scheme and the Hill Farm Allowance, were due to close.

Chestnut and mimosa tannin silages: Effects in sheep differ for apparent digestibility, nitrogen utilisation and losses

This paper reports effects of chestnut and mimosa tannins on N utilisation in sheep. Tannins were added to grass either at ensilage or incorporated into grass silage at feeding. The study used an 8 × 5 incomplete Latin Square design with eight mature wether sheep and five 21-day periods. Tannin additions reduced in vivo apparent digestibilities of dry matter (DM), organic matter (OM) and neutral detergent fibre (aNDFom) compared with the untreated control silage (P<0.001). Reductions ranged from 7.6% for DM to 8.5% for aNDFom. Chestnut compared to mimosa tannin silages produced higher values for DM intake (734 g/day versus 625 g/day) and in vivo digestibility for DM, OM and aNDFom (0.66, 0.68 and 0.69 versus 0.61, 0.63 and 0.62; P<0.001). A substantial shift occurred in the pattern of N excretion in sheep fed the tannin versus control silages. As a proportion of daily N intake, urinary N losses were lower (56.4 g/100 g N versus 65.1 g/100 g N intake) and faecal N losses were higher (40.2 g/100 g N versus 29.8 g/100 g N intake) for sheep fed the tannin silages compared with those fed the control grass silage (P<0.001). Nitrogen intake was higher in sheep fed the chestnut compared to mimosa tannin silages (16.2 g/day versus 13.4 g/day; P<0.001), reflecting the lower DM intake of sheep fed the mimosa silages. However, faecal N loss was lower for chestnut compared to mimosa tannin silage fed sheep (38.2 g/100 g N versus 42.1 g/100 g N intake; P<0.01), resulting in higher N retentions with the chestnut compared to the mimosa silage fed sheep (5.49 g/100 g N versus 1.38 g/100 g N intake). Faecal N losses were also higher when tannins were added during ensiling rather than at feeding (P<0.05). Although there was no overall effect of tannins on N retention in mature wether sheep, it is likely that productive ruminants with higher protein requirements would retain more N from silages containing chestnut tannins. Tannins added externally to grass silages may generate some benefits on N utilisation and environmental N excretions in sheep fed the silages.