A new model is presented that relates the numbers of bolters in sugar-beet crops to an intensity of vernalization calculated as the accumulated number of hours between sowing and the end of June that temperatures were between 0 and 13°C, with each temperature within this range differentially weighted for its vernalizing effect. The model allows varieties to be characterized in terms of a threshold number of vernalizing hours needed to induce bolting (the vernalization requirement) and the increase in the proportion of bolted plants with each additional 10 vernalizing hours accumulated above this vernalizing threshold (the bolting sensitivity). When parameterized for variety, the model allows the level of bolting to be predicted for crops sown on specific dates in particular locations.

Data from variety-assessment trials done at a wide range of locations throughout the main UK sugar-beet growing areas between 1973 and 2006, and from early sown bolting trials done at a few sites between 2000 and 2008, were used to define specific aspects of the model. These included the range and weightings of vernalizing temperatures, the period during which vernalization occurs, and the temperatures likely to cause plants to become devernalized.

The vernalization-intensity bolting model was parameterized and validated using separate subsets of the UK variety-assessment trial data. It was shown to be more discriminating and robust than an existing ‘cool-day’ model, which relates bolting to the number of days from sowing in which the maximum air temperature was below 12°C. Examples are given of the use of the new model to assess the bolting risk associated with early sowing in different regions of the UK, to interpret recent patterns of bolting (especially the large numbers of bolters seen in some commercial crops in 2008), and its potential use as an advisory tool.

The main objective of the current study was to analyse how water application through a sprinkler irrigation system influences yield of onion (Allium cepa L.), taking into account water application heterogeneity and the effects on theoretical crop evapotranspiration (ETc). Field experiments were conducted on commercial onion plots, irrigated with a permanent sprinkler irrigation system, located in Albacete, Spain, over two irrigation seasons. Two experimental plots were selected each study year: plot A (PA), in which water was applied heterogeneously by using sprinklers with different nozzle combinations, and plot B (PB, used as the reference plot) in which the four sprinklers were maintained with the same nozzle combinations. Both experimental plots were divided into 25 subplots with the aim of studying the water distribution (measured as Christiansen uniformity coefficient (CU)), the impact on the actual evapotranspiration (ETa) and the yield obtained. Irrigation was scheduled using a daily simplified water balance method within the root area following the approach of the Food and Agriculture Organization. In the present study, sprinkler irrigation in PA resulted in lower CU (65–82% lower in 2002 and 59–79% lower in 2005) compared with PB (78–92% lower in 2002 and 79–93% lower in 2005). Between 30 May and 18 August 2002, the estimated crop water requirements in PA in the absence of water deficit was 22 mm over the accumulated value of ETc (491 v. 469 mm), while estimated crop water requirements under water deficit were 187 mm below ETc (282 v. 469 mm). In 2005, between 29 May and 25 August, ETa without water deficit was more similar to ETc (458 v. 444 mm) but Eta under water deficit was 242 mm. The greater uniformity of water distribution in PB was translated into a greater uniformity of yield distribution. A smaller range in yield was observed in PB when compared with PA. No statistically significant differences were observed between PA and PB in the crop quality parameters bulb moisture content, total soluble solids, pH and total acidity.

Agricultural crop management decisions often require data on hydraulic properties of soils. Little information is available on hydraulic properties of clay soils that are impounded by rainwater (known as ‘Haveli’ lands) every year during the monsoon season in large tracts of Madhya Pradesh in India. Estimating hydraulic properties using global pedotransfer functions (PTFs) is one possible way to collect such information. Rules in the widely used global PTF Rosetta were executed to obtain estimates of two important hydraulic properties, namely soil water retention characteristics (SWRC) and saturated hydraulic conductivity (Ks). SWRC estimates obtained with maximum input (particle size distribution, bulk density, field capacity and permanent wilting point) in Rosetta were relatively closer to the laboratory-measured data as compared with the estimates obtained with lower levels of input. Root mean square error (RMSE) of estimates ranged from 0·01 to 0·05 m3/m3. Hierarchical PTFs to predict Ks from basic soil properties were derived using statistical regression and artificial neural networks. Evaluation of these indicated that neural PTFs were acceptable and hence could be used without loss of accuracy.

Genetic variability in carrots is a consequence of allogamy, which leads to a high level of inbreeding depression, affecting the development of new varieties. To understand the extent of genetic variability in 40 elite indigenous breeding lines of subtropical carrots, 48 DNA markers consisting of 16 inter simple sequence repeats (ISSRs), 10 universal rice primers (URPs), 16 random amplification of polymorphic DNA (RAPD) and six simple sequence repeat (SSR) markers were used. These 48 markers amplified a total of 591 bands, of which 569 were polymorphic (0·96). Amplicon size ranged from 200 to 3500 base pairs (bp) in ISSR, RAPD and URPs markers and from 100 to 300 bp in SSR markers. The ISSR marker system was found to be most efficient with (GT)n motifs as the most abundant SSR loci in the carrot genome. The unweighted pair group method with arithmetic mean (UPGMA) analysis of the combined data set of all the DNA markers obtained by four marker systems classified 40 genotypes in two groups with 0·45 genetic similarity with high Mantel matrix correlation (r=0·92). The principal component analysis (PCA) of marker data also explained 0·55 of the variation by first three components. Molecular diversity was very high and non-structured in these open-pollinated genotypes. The study demonstrated for the first time that URPs can be used successfully in genetic diversity analysis of tropical carrots. In addition, an entirely a new set of microsatellite markers, derived from the expressed sequence tags (ESTs) sequences of carrots, has been developed and utilized successfully.

Granule size distribution of wheat starch is an important characteristic that may affect the functionality of wheat products. Light intensity is one of the main factors affecting grain yield and quality. Two high-yield winter wheat cultivars were grown under shade to evaluate the effect of low light intensity after anthesis on starch granule size distribution and starch components in wheat grains at maturity. Shading caused a marked drop in both grain yield and starch yield and led to a significant reduction in the proportion (both by volume and by surface area) of B-type starch granules (⩽9·9 μm), with an increase in those of A-type starch granules (>9·9 μm). This would suggest that the production of B-type starch granules was more sensitive to shading than that of A-type starch granules. It was also found that the proportion by volume of A-type starch granules was significantly increased and that of B-type starch granules was significantly decreased by shading at different grain filling stages, especially at middle and late grain-filling stages. However, shading had little effect on the proportional number of B-type starch granules. The present results suggested that, under dim light conditions, the limited substrate for starch accumulation was mainly partitioned towards hypertrophy (larger granules) not hyperplasia (more) of starch granules.

Field and pot experiments were conducted to investigate the effects of defoliation on crop performance and the possibility of using defoliation as a method for conserving soil moisture. The study was conducted during 2006–2008, over two growing seasons of winter wheat (Triticum aestivum L.) in the North China Plain. Three levels of defoliation (mild, moderate and severe) were imposed on winter wheat in the field during the following crop phases and conditions: at heading, at anthesis under water deficit conditions and at anthesis under two or three levels of irrigation. Additional pot experiments with three levels of defoliation under two water regimes were arranged. The results showed that both the intensity of defoliation and the timing of defoliation significantly reduced grain production. Under wet conditions the reduction was over 20%, while under dry conditions the reduction was c. 12%. Yield reduction was greater for defoliation at heading than at anthesis and it was mainly caused by a reduction in kernel weight. Mild defoliation (top three leaves retained) did not affect grain yield. Moderate defoliation (top two leaves retained) slightly reduced grain production. Root length density in the topsoil profile was significantly reduced by severe defoliation at anthesis under wet conditions, but it increased under dry conditions. Dry matter remobilization to grains under moderate and mild defoliation was increased and resulted in a relatively higher harvest index (HI). The photosynthetic rate of the leaves remaining after defoliation was enhanced under all soil moisture conditions. Although defoliation reduced the seasonal water use (ET), the yield reduction was much greater than the reduction in ET under severe defoliation, resulting in lower water use efficiency (WUE). The results show that conserving soil moisture by removing leaves might not be an economic choice. Under the conditions of the present study, the WUE of winter wheat was not improved by defoliation; however, in very dry conditions the reduction in ET by defoliation might help the crop survive.

The Mediterranean region is experiencing unrelenting land-use pressure, largely driven by population growth. Long-term cropping system trials can guide crop and soil management options that are biophysically and economically sustainable. Thus, an extensive cereal-based rotation trial (1983–98) was established in northern Syria, to assess various two-course rotations with durum wheat (Triticum turgidum Desf.). The alternative rotations were: continuous wheat, fallow, chickpea (Cicer arietinum), lentil (Lens culinaris), medic (Medicago spp.), vetch (Vicia sativa) and watermelon (Citrullus vulgaris) as a summer crop. Ancillary treatments were: nitrogen (N) fertilizer application to the cereal phase (0, 30, 60 and 90 kg N/ha) and variable stubble grazing management (zero or stubble retention, moderate and heavy grazing). Both phases of the rotation trial occurred each year. The soil is a fine clay, thermic Calcixerollic Xerochrept. Seasonal rainfall was the dominant factor in influencing overall yields. Rotations significantly influenced yields, being highest for fallow (2·43 t/ha), followed by watermelon (similar to fallow), vetch, lentil, medic and chickpea, and least for continuous wheat (1·08 t/ha). Overall, yields increased consistently with added N, but responses varied with the rotation. The various stubble grazing regimes had little or no effect on either grain or straw yields. While the trial confirmed the value of fallow and the drawbacks of continuous cereal cropping, it also showed that replacing either practice with chickpea or lentil, or vetch for animal feed, was potentially a viable option. Given favourable economics, legume-based rotations for food and forage could contribute to sustainable cropping throughout the Mediterranean region.

Field experiments (15 years) were carried out to study the effects of no-tillage (NT) and conventional tillage (CT) management practices on the soil chemical properties, microbial biomass, soil enzymatic activities and winter wheat yield on a cinnamon soil in Shanxi, on the Chinese Loess Plateau. Compared to CT, NT increased soil organic carbon, soil total nitrogen and soil total phosphorus in the 0–100 mm layer by 25, 18 and 7%, respectively. Microbial biomass C and N contents under NT were 41 and 57% greater than under CT on the same layer. In general, higher enzymatic activities were found in the more superficial layers of soil under NT than under CT in the same layer. Winter wheat yield was c. 20% higher under NT than under CT. These findings have implications for understanding how conservation tillage practices improve soil quality and sustainability in the rainfed dryland farming areas of northern China.

The aim of the current study was to compare three methods for determining the influence of different feeding strategies on the gut microbiota of piglets. Forty-eight weanling piglets were fed four different diets enriched with insoluble dietary fibre (wheat bran and pollen from Pinus massoniana). Starting from ileal and colonic samples, the total microbial DNA was isolated and bacterial parameters (lactobacilli, bifidobacteria, Bacteroides vulgatus and total bacterial counts) were quantified using real-time polymerase chain reaction (PCR). The results for lactobacilli, bifidobacteria and total bacterial counts were compared with those obtained by fluorescence in situ hybridization (FISH) and cultivation method. No significant differences could be observed between dietary treatments with real-time PCR and FISH for all investigated parameters. Comparing the applied three methods no consistent results were achieved, whereas FISH usually showed lower values. It was shown that real-time PCR can be regarded as an alternative to conventional techniques and also as a complement to results obtained from conventional culture method.

The aim of the current study was to determine how cooling and supplemental recombinant bovine somatotropin (rbST) affect body function with respect to digestion kinetics, digestibility and other variables relevant to milk production in cross-bred Holstein cattle. Ten primiparous cross-bred dairy cattle (0·875 Holstein Friesian×0·125 Red Shindi) were used and divided into two groups of five animals each that were housed in a normal shaded barn (NS barn; non-cooled cows) and in a shaded barn with mist-fan cooling (MF; cooled cows). The cows in each group were supplemented with rbST in early, mid and late stages of lactation with three consecutive subcutaneous injections of 500 mg rbST every 14 days. All cows were fed the same total mixed ration twice daily at approximately 1·1 of assumed ad libitum intake and water was offered ad libitum. During the experimental periods, values of ambient temperatures and temperature humidity index (THI) in the NS barn were significantly higher than in the MF barn, whereas the relative humidity in the MF barn was significantly higher than in the NS barn (P<0·01). The respiration rate and rectal temperature were significantly higher for non-cooled cows than for cooled cows during the daytime whether there was or was not rbST supplementation. Supplementation of rbST for either cooled or non-cooled cows significantly increased dry matter intake (DMI), the efficiency of feed utilization and milk yields (P<0·05). Digesta kinetics using chromic oxide as an external marker showed a high digesta passage rate constant and low mean retention time of digesta in cows either by cooling or supplementation of rbST, whereas no changes were seen for the digestibility of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fibre (NDF) and acid detergent fibre (ADF). The half-time of Cr2O3 in the whole digestive tract of cooled cows was lower than those of non-cooled cows and significantly decreased (P<0·05) during rbST supplementation in both groups in all stages of lactation. The magnitude of responses for the digesta passage rate and efficiency of feed utilization were larger in animals supplemented with rbST than in animals under MF cooling only.

The main effect of cooling and supplemental rbST was to improve digestion by an increase in the rate of passage of digesta and in turn an increase in feed intake. Digestibility was not influenced by changes in passage rate of digesta either by cooling or rbST supplementation. Milk production in response to rbST supplementation is probably enhanced with cooling. The increased milk production induced by rbST supplementation was mediated by increased efficiency of feed utilization without changes in diet digestibility.

This group, which represents the reformed Operational Research (OR) Society's Agriculture and Related Industries group (http://www.orsoc.org.uk), promotes the use of OR (or the application of the scientific method) in solving management and governance problems within this sector. The theme of this meeting was to look at models concerned with making better decisions for the management or governance of the agricultural and natural resource industries. This first one day meeting was at Reading University, Berkshire, UK on the 2 April when the following papers were read.