In Sub-Saharan Africa, cowpea is well known for its ability to survive under conditions of water stress and it plays an important role in regions where drought is the factor most limiting to crop yield. In the present study, the drought tolerance levels of 20 African cowpea accessions from three countries were evaluated. A number of the genotypes showed drought tolerance, the merits of stomatal behaviour and cell membrane stability to assess drought tolerance was demonstrated. Damage to the cell membranes caused by drought was less in tolerant accessions. Stomatal opening was also better regulated; the opening was smaller under drought conditions, thus reducing transpiration (T). The wide range of drought tolerance observed among the accessions suggests the possibility of breeding drought-tolerant cultivars in cowpea. Drought-tolerant accessions included Bafoussam 1, M.66, Bafoussam 3, Hluhluwa, Bafoussam 4, Balen, Makueni, Bafoussam 2 and Okhalweni and these could be recommended to breeders as valuable material for drought tolerance improvement in cowpea.

Currently, society awareness, legislations and competing markets demand dairy farming systems which are sustainable. In the near future, farm management and animal genetics will be key elements in developing such sustainability. Although the effect of farm management on some attributes of sustainability has already been studied, the impacts and scope for realizing goals of agricultural multifunctionality through genetic changes are still to be tested. Sustainable and Integrated Management Systems for Dairy Production (SIMSDAIRY) is a new farm level modelling framework which integrates these concepts to practical actions and brings all of this complexity into an operational and scientific modus operandi.

The current paper provides a brief description of the structure of SIMSDAIRY and an example of how it can be used to compare the scope for improving the overall sustainability of a dairy farm by: (i) future system changes aimed at improving genetic characteristics of plants and animals with (ii) current system structural changes aimed at improving nutrient management efficiency. In order to do this comparison, management factors and new genetic traits from plants or/and animals, acting singly or in combination, are evaluated against a baseline dairy farm scenario. Sustainability is measured in terms of targets associated with: (i) the Nitrates Directive, (ii) phosphorus (P) threshold for eutrophication, (iii) the Kyoto Protocol, (iv) the Gothenburg Protocol, (v) an adequate net farm income for standard of living and acceptable standards of (vi) quality of milk, (vii) animal welfare, (viii) level of biodiversity, (ix) landscape aesthetics and (x) soil quality.

Results suggest that genetic-based changes offer greater scope than management-based ones to improve sustainability up to an acceptable level. Costs associated with management changes are often too high within current socio-economics circumstances. Optimizing nitrogen (N) mineral fertilizer rate and timing was the only management-based measure that, while improving most of the environmental and biodiversity indices, resulted in improved economic results. Some genetic-based changes offered substantial scope for reducing environmental losses while having economic benefits. However, only those decreasing the crude protein (CP) of the plant and increasing the diet N cow partition into milk seemed to result in non-significant pollution swapping and be achievable in the nearby future.

Methane, in addition to being a significant source of energy loss to the animal that can range from 0·02 to 0·12 of gross energy intake, is one of the major greenhouse gases being targeted for reduction by the Kyoto protocol. Thus, one of the focuses of recent research in animal science has been to develop or improve existing methane prediction models in order to increase overall understanding of the system and to evaluate mitigation strategies for methane reduction. Several dynamic mechanistic models of rumen function have been developed which contain hydrogen gas balance sub-models from which methane production can be predicted. These models predict methane production with varying levels of success and in many cases could benefit from further development. Central to methane prediction is accurate volatile fatty acid prediction, representation of the competition for substrate usage within the rumen, as well as descriptions of protozoal dynamics and pH. Most methane models could also largely benefit from an expanded description of lipid metabolism and hindgut fermentation. The purpose of the current review is to identify key aspects of rumen microbiology that could be incorporated into, or have improved representation within, a model of ruminant digestion and environmental emissions.

The objective of the present paper was to propose a statistical approach to support selection of the most promising genotypes in a breeding programme. The approach is based on applying two state-of-the-art statistical methodologies, likelihood-based path analysis and model-based cluster analysis. The first method is applied to find a causal mechanism lying behind a biological process of development of final crop yield. These results are then used for weighting traits to be used in cluster analysis, which helps select genotypes possessing a desirable level of yield and yield-contributing traits. An application of the approach is presented for a 2-year study on 22 grasspea genotypes, two cultivars (Derek and Krab) and 20 mutants from those cultivars. Seed yield/plant and seven yield-related traits were studied. Among these, plant height, number of branches/plant, pod length and number of seeds/plant determined seed yield; number of pods/plant influenced seed yield only for 2002. These results were used for appropriate weighting in cluster analysis, which indicated that cultivar Krab and its two mutants, K3 and K64, had the best level of the traits and were the most stable genotypes.

The free volatile compounds of two successive vintages of cv. Caiño Tinto, Caiño Bravo and Caiño Longo red wines, together with the volatile compounds released after the enzymatic hydrolysis of their glycosidically bound forms, were identified and quantified by gas chromatography using a flame ionization detector (GC/FID). All these wines possessed the same free volatile compounds; Caiño Longo wines showed the highest concentrations and Caiño Tinto wines the lowest. In all cases, the release of the bound forms of these compounds may contribute to the final aroma, from both a qualitative standpoint (with the appearance of free 4-terpineol, nerol and geraniol) and quantitative standpoint (notable increases were recorded for most of the compounds detected). The principal component analysis (PCA) showed a good separation of the different wine cultivars and vintages. Caiño Tinto wines were more homogeneous between vintages than the others.

Watermelon is a crop with a high water demand and is frequently grown under conditions of higher than normal root-zone salinity. In the present study, seedlings of watermelon (cv. Fantasy, Citrullus lanatus (Thunb.) Matsum & Nakai) were grown either ungrafted or grafted on three rootstocks: Strong Tosa, S1 (both Cucurbita maxima×Cucurbita moschata), or Emphasis (Lagenaria siceraria). All the plants were exposed to an NaCl-induced salinity stress (electrical conductivity, EC=2·2, 4·0, or 6·0 dS/m). The vegetative growth of all the plants substantially reduced after 2 weeks of exposure to 6·0 dS/m; however, growth of the plants grafted on Strong Tosa reduced less than that of the others. The leaf water content and specific leaf area (SLA, m2/g) decreased with an increasing salinity in grafted plants, but not in ungrafted plants. Salinity induced an increase of superoxide dismutase (SOD) activity in grafted plants up to two-fold depending on the rootstock, whereas it had no effect on this enzyme activity in ungrafted plants. Leaf Na+ concentration increased with increasing salinity in ungrafted and S1 grafted plants, whereas there was no significant leaf Na+ accumulation in Emphasis and Strong Tosa grafted plants. Leaf K+ concentration was affected by the rootstock but not by salinity, thus, the ability to keep a high K+/Na+ ratio was achieved mainly by limiting leaf Na+ concentration. The rootstock determined the leaf Cl− accumulation, with lower overall concentrations found if plants were grafted on the S1 rootstock than on Emphasis or ungrafted plants. Salinity significantly decreased the leaf NO3− concentration on Emphasis grafted plants only, while the NO3−/Cl− ratio was reduced in all the rootstocks. The capacity of Strong Tosa to withstand salt stress better than other tested rootstocks was probably due to the ability to induce anatomical adaptation (SLA) and SOD activity in response to salt stress, and also to the efficiency of Na+ exclusion from the shoot.

Male-sterile, female-fertile plants were used to produce hybrid soybean seed. Manual cross-pollination using male-sterile plants to produce large quantities of hybrid seed is difficult and time-consuming because of the low success rate in cross-pollination. Insect pollinators may be suitable vectors to transfer pollen, but the most suitable vector for pollen transfer from the male parent to the female parent has not been identified for soybean. The objective of the present study was to evaluate seed-set on four male-sterile, female-fertile soybean lines by using alfalfa leafcutting bees (Megachile rotundata (F.)) and honey bees (Apis mellifera (L.)) as pollinators. Seed-set was evaluated in summers 2003 and 2005 near Ames, Iowa, USA and in summers 2003, 2004, and 2005 near Wooster, Ohio, USA. Neither the effect of pollinator species nor the interaction effect of pollinator species×location was significant for any year. Honey bees performed similarly to alfalfa leafcutting bees at both locations. The results indicated significant differences for seed-set among male-sterile lines, suggesting preferential pollination. Male-sterile lines, ms1 (Urbana) and ms2 (Ames 2), had higher cross-pollinated seed-set compared to ms6 (Ames 1), and ms6 (Corsoy 79). At the Ames location, ms1ms1 (Urbana) plants had the highest seed-set (50·16 seeds per male-sterile plant in 2005). At the Wooster location, ms1ms1 (Urbana) plants also had the highest seed-set (92·04 seeds per male-sterile plant) in 2005. Costs and local conditions need to be addressed to support the choice of either pollinator species as a pollination vector to produce hybrid soybean seed.

The control effect of Cucurbita ficifolia (pumpkin) leaf acetone extract on caterpillars of the small cabbage butterfly Pieris rapae Linnaeus (Lepidoptera: Pieridae) was observed in laboratory and field experiments from 1 March 2006 to 30 May 2007. The mechanism of the action by which pumpkin leaf extract (PLE) controls small cabbage caterpillars was examined for feeding restraint, and the values for 0·50 feeding restraint concentration (FC50) and 0·95 feeding restraint concentration (FC95) after 12 and 24 h were estimated. The results showed that the absolute anti-feeding activity for fourth instar caterpillars after 12 h was 0·65 and after 24 h was 0·56, while relative anti-feeding activity was 0·57 after 12 h and 0·59 after 24 h. Field experimental results indicated that the leaf protection effects increased up to day 7, while the feeding control effects remained constant. Comparison of the profits from pest management using indigenous pesticides, biological pesticides and chemical pesticides and without pest management suggested that there are currently economic benefits associated with the use of indigenous pesticides, such as PLE.

In crop experiments measurements are often made by a judge evaluating the crops' conditions after treatment. In the present paper an analysis is proposed for experiments where plots of crops treated differently are mutually ranked. In the experimental layout the crops are treated on consecutive plots usually placed side by side in one or more rows. In the proposed method a judge ranks several neighbouring plots, say three, by ranking them from best to worst. For the next observation the judge moves on by no more than two plots, such that up to two plots will be re-evaluated again in a comparison with the new plot(s). Data from studies using this set-up were analysed by a Thurstonian random utility model, which assumed that the judge's rankings were obtained by comparing latent continuous utilities or treatment effects. For the latent utilities a variance component model was considered to account for the repeated measurements. The estimation was based on a Bayesian approach, which was analysed via Markov Chain Monte Carlo sampling. A simulation study showed that the approach was able to estimate the relative ordering of the treatments. The efficiency of the estimation increased with the overlap of the ranked observations. The approach was compared with a more traditional analysis of variance analysis applied to a proportional score for each plot by applying both methods to a real experiment. The relative ranking of the treatment effects were almost the same for both approaches. This method seems to be less sensitive to the judge and also eliminates any possible drift over the judging process in the more traditional method.

Young leaves and pods of okra (Abelmoschus esculentus (L.) Moench) are edible, and so a crop management strategy for removing edible leaves while sustaining good pod yields is required. Pruning treatments were imposed on apically debudded okra plants for 3 years to assess effects of removing a quarter, half or three-quarters of the primary branches on growth and fresh leaf and pod yields. Pruning significantly (P<0·05) delayed fruiting by 8–10 days, extended length of harvest duration by 12–15 days and increased number of pods/plant by 10–40% and pod yield by 9–36% more than the control plants which had neither apical bud removal nor pruning. However, no difference in pod weight or pod length was found between these treatments and the control. Three-quarters pruning significantly (P<0·05) increased fresh leaf yield by 29–49%, but not all the leaves were desirable for consumption because of high fibre content. Decreases were seen in the numbers of secondary branches, shoot dry weight and pod yields (by 40–57, 22–36 and 22–30%, respectively, more than a quarter or half pruning). Although early production of pods in the control plants is often important for early maturity and high market prices, the present study found that a delay in fruiting, an extension in length of harvest duration and an increase in pod yield in plants with a quarter or half pruning enhanced staggered production and maximal pod yield. This helps to ensure a better market price and to enable growers avoid a glut on the market. A direct promotional effect of pruning on pod yields provides a possible strategy for growing okra for both leaf and pod harvests. A quarter or half pruning from the upper parts of the main stems of apically debudded plants to ensure good production and quality of leaves and pods is therefore recommended if okra is to be grown for both leaf and pod yields.

Grassland forbs are important constituents of swards under low-input management. The hypothesis tested was that herbage from unfertilized swards consisting of a mixture of perennial ryegrass (Lolium perenne), white clover (Trifolium repens), dandelion (Taraxacum officinale) and ribwort (Plantago lanceolata) (treatment GCF) would exert a significant effect on the composition and quality of silage for rumen microbes compared with herbage from nitrogen-fertilized (50 kg N/ha/cut) pure ryegrass swards (treatment GN) or unfertilized ryegrass white clover swards (treatment GC). GCF had average proportions of clover and forb of 0·21 and 0·58, respectively. The crude protein and fibre fractions declined and non-fibrous carbohydrates (NFC) increased from GN over GC to GCF. Irrespective of cutting date (spring and summer), GN showed extremely high ammonia (NH3) concentrations, whereas GCF resulted in the highest concentrations of lactic acid coinciding with the lowest contents of butyric acid and ethanol. The ratios between the soluble and less soluble N fractions decreased in the order GN>GC>GCF. A similar sequence was observed in RUSITEC for the apparent disappearance rates of crude protein and fibre fractions. The concentration of NH3-N in the fermenter fluid declined in the order GN>GC>GCF. GCF produced less short-chain fatty acids (SCFA) than GN and GC. Microbial nitrogen (MN) flow was not significantly different between treatments but tended to decline in the order GN>GC>GCF, whereas the proportion of MN originating from NH3-N increased inversely. The efficiency of microbial protein synthesis was unaffected by the different silages. It is concluded that forb-rich swards are suitable for the preparation of high quality silages. There is a need for further investigation into postruminal availability and suitable supplementation for such silages in order to fully exploit their potential for improving the efficiency of nitrogen utilization in ruminant nutrition.

A series of studies were carried out to measure the methane (CH4) production by Japanese goats fed 19 different diets (D1–D19) varying in nutritive composition in the open circuit respiration chamber (RC) and to compare them with CH4 estimated by the in vitro gas production test (IVGPT). Adult Japanese goats (>2 years old) with a mean body weight of 26±5·4 kg were used in these experiments. Each diet was fed to four randomly selected goats and feeding was carried out at 1·1 maintenance (M) as per National Research Council (NRC) (1981) for goats. Average CH4 emission by goats in the RC ranged from 0·23 to 0·39 (mean value 31 ml/g dry matter intake (DMI)); when it was expressed as a proportion of gross energy or, with methane conversion rate (MCR), it ranged from 5·0 to 8·2, with an average of 6·6. Incorporation of by-products like sweet potato vine silage (SPVS) (P=0·016), dried pumpkin (P=0·052) and brewers' grain in the diet suppressed (P<0·01) methanogenesis in goats, when compared with that of standard farm diet (D1). The CH4 output measured in the RC was very close to that estimated from the gas collected after 24 h and higher after 48 h of in vitro incubation. Although composition of the diets' acid detergent fibre (ADF) had a significant effect on methane emission, methane output estimated by IVGPT was very close to that measured in the RC demonstrating that this system could be used to estimate the CH4 production potential from diets in preparing a database and also in the planning of mitigation strategies in small ruminants to improve their performance as well as to reduce greenhouse gas emissions.

An isotope dilution method using [1-13C]leucine (Leu) infusion together with open-circuit calorimetry was applied to determine the effect of metabolizable protein (MP) intake on rates of plasma Leu turnover and whole body protein synthesis (WBPS) in six heifers. WBPS rate was estimated from rate of plasma Leu turnover and Leu oxidation to carbon dioxide. The experiment consisted of three levels of MP intake and was conducted in a two 3×3 Latin square designs of three 21-day periods. The experimental diet consisted of mixed hay, maize and soybean meal. Dietary MP intake of each dietary treatment was 4·3, 4·5 and 4·9 g/kg BW0·75/day by changing maize and soybean meal weights. Metabolizable energy (ME) intake was similar for all dietary treatments. When plasma α-[1-13C]keto-isocaproic acid enrichments were used as markers indicating intracellular Leu enrichments, plasma Leu turnover rate (LeuTR) increased (P=0·012) and WBPS tended to increase (P=0·091) as MP intake increased. In contrast, plasma LeuTR and WBPS were not influenced if plasma [1-13C]Leu was taken to indicate intracellular Leu enrichments. Total and plasma Leu oxidation rates did not change but intracellular Leu oxidation increased (P=0·044) with increasing MP intake. In heifers, it is suggested that rates of plasma Leu turnover and WBPS are influenced by dietary MP intake, independent of ME intake, although the change in MP intake was relatively small.

Selection within elite cotton cultivars is ineffective; it is believed that they are genetically homogeneous. Research in other crops, however, has verified significant intra-cultivar variation based either on phenotypic differentiation or molecular analysis techniques. The present study primarily investigated possible intra-cultivar variation for seedcotton yield. Honeycomb selection within three elite cotton cultivars, on the basis of single-plant seedcotton yield and under the ultra-low density of 1·2 plants/m2, was performed. From each cultivar, six selfed (hand-pollinated) plants were selected and seed of each selected plant constituted a separate line. The 18 first generation lines were evaluated in three locations at a density of 1·2 plants/m2. Within each line, the 10 selfed plants which yielded the highest were selected. Mixed seed from these selected plants constituted the respective second generation line. Offspring performance of the 18 second generation lines was also tested in three locations at a density of 1·2 plants/m2. The results were indicative of intra-cultivar variation, since significant differentiation between lines of each cultivar was found for seedcotton yield per plant, averaged across two years and three locations. Additionally, significant intra-cultivar variation was found for fibre quality properties (length and micronaire, but not strength and uniformity) averaged across two years in a single location, as well as for physiological traits (leaf carbon isotope discrimination, ash content and K concentration) averaged across two years and three locations. In comparison with the original cultivars the second generation lines had higher seedcotton yields supporting the existence of exploitable genetic variation. The conclusion was that honeycomb selection in the absence of competition could be an effective technique in breeders' seed treatment in order to avoid gradual degeneration and beneficially exploit any latent or newly developed genetic variation.

This group, which is concerned with the applications of mathematics to agricultural science, was formed in 1970 and has since met at approximately yearly intervals in London for one-day meetings. The fortieth meeting of the group, chaired by Dr John Thornley of Henley-on-Thames, UK and the Centre for Nutrition Modelling, University of Guelph, Canada, was held in the Kohn Centre at the Royal Society, 6 Carlton House Terrace, London on Friday, 11 April 2008 when the following papers were read.

L-methionine is a sulphur-containing nutritionally essential amino acid. It has a number of important roles in epidermal and dermal tissues of the integument of animals. Failure of normal function of these tissues in the hoof (claw) is a cause of lameness in cattle. Little is known about quantitative relationships between post-absorptive concentrations of nutrients including sulphur-containing amino acids and uptake and utilization by epidermis and dermis of the bovine claw. These parameters were studied at the tissue level by use of an established in vitro claw explant system using tissue from cattle of beef or dairy origin and L-[35S]-labelled methionine as tracer. The results showed that uptake of L-methionine by freshly prepared solear explants in Dulbecco's Modified Eagle Medium/F-12 Nutrient Mix (DMEM/F12) (1:1) medium containing 1·0 mmol L-methionine/litre was concentrative after 5–8 min, essentially linear for up to 10 min and became curvilinear thereafter. Maximum uptake and steady state conditions were obtained at approximately 30 min. Further measurements were made following 21 h incubation in culture medium. Under conditions of varying concentrations of L-methionine and measurement of uptake after 30 min, the presence of a saturable curve, that obeyed Michaelis–Menten kinetics, was demonstrated. Values of 3·61 mmol/litre and 5·84 mmol/kg intracellular water/30 min were obtained for KM and Vmax, respectively. Uptake was not influenced by L-cysteine and L-cystine concentrations in the culture media.

Similar culture and incubation conditions were used in subsequent studies of DNA and protein synthesis. These showed that rates of incorporation of L-methionine into protein fractions and stimulation of DNA synthesis measured by methyl-thymidine incorporation were dependent on L-methionine concentrations in the medium. Maximal rates occurred at approximately 50 μmol/litre, which is in the normal physiological range, and at 1% of maximum uptake capacity. Examination of histological sections by autoradiography showed localization of L-[35S]-labelled methionine in basal and suprabasal epidermal cells with limited retention in dermis. Measurement, by a range of histological, immunohistochemical, electrophoretic, western blotting and autoradiographic techniques, provided further evidence of L-methionine-dependent regulation of proliferation, differentiation and synthesis of proteins under physiological concentrations, by epidermal horn-forming cells.

A key role for L-methionine is suggested in the production of horn in bovine claw. The extrapolation of these in vitro data provides guidance for strategies to optimize methionine supply to claw tissues in vivo. Such extrapolation suggests the appropriateness of delivery of systemic concentrations of 50 μmol L-methionine/litre to maximize proliferative and protein depositional activity in solear epidermis and dermis in vivo.

The working group, which is concerned with operational research methods and applications to agricultural science in its broad meaning (i.e. including Forest Management and Fisheries), was formed in 2003 within the European Association of Operational Research Societies (EURO). The first meeting of the group was held at the former Silsoe Research Institute in 2004. The group intends to have regular meetings in Europe at approximately yearly intervals, usually within the EURO Conferences. However, the next meeting will be held in 2008 within the British Operational Research Society's OR50 Conference in York, followed by the EURO XXIII Conference in Bonn in 2009 and the EURO XXIV Conference in Lisbon in 2010. The third meeting of the working group, chaired by Dr L. M. Plà of the University of Lleida, with the assistance of D. L. Sandars of Cranfield University and organized as a stream within the XXII EURO Conference, was held at the University of Economics in Prague from 8 to 11 July 2007 where the following papers were read in a set of 10 sessions.