Cereal Area Research Articles

THE EFFECTS OF AGRICULTURAL EUROINTEGRATION ON THE AGRICULTURAL PRODUCTION

The agricultural sector may contribute significantly to supporting the economic growth, having natural resources and great possibilities for the increase of the productivity. The future changes in the agricultural productivity in the European countries will be determined by the same factors as for the other sectors of the economy, such as the access to capital and technology and the improvement of the management and restructuring in the agriculture. The economic comparative method was used to compare macroeconomic indices of EU -15 countries and of new member countries. According to these facts, some conclusions were displayed, conclusions regarding their position in the agricultural sector of European Union. There were used data published by European Commission and reports on development of the new Member States. The implementation of the CAP in the NMS will lead to a moderate growth in agricultural production. This will be manifested through an expansion of the individual sectors (in particular poultry, oilseeds and possibly cereals), and coincide with a modernisation and intensification of farm management practices. The combined cereal and oilseed area which is expanding will probably replace some current crops. It may, however, also absorb a part of the presently abandoned arable land as well as areas of fertile soil that have been converted into grass because of the low arable prices. It could even lead to the ploughing up of some permanent grasslands of high nature conservation value. Low input livestock systems, responsible for creating and maintaining these species-rich grassland habitats, will not benefit sufficiently from the first pillar proposals and will not be able to expand from their present low production levels. The ongoing restructuring process suggests however that it will be gradually exploited and fully used only in the longer term. Agricultural production in the New Member States will increase slightly over the medium term due to the higher prices of production which are also significantly stable, and to the increasingly favourable perspectives on the Single Market, and the rural development measures. Reorganization will depend on new investments. Foreign direct investments are the key element of reorganization. The production in most of the new Member States does not rise up to the EU-15 standards and this may be a barrier for the NMS markets and will undermine their competitiveness.

Effect of cereal harvesting method on a recent population decline of Corn Buntings Emberiza calandra on the Western Isles of Scotland

Capsule Population decline since 1995 is associated with the harvesting of cereals as arable silage. Aim To survey Corn Bunting populations on the Western Isles and test whether population changes since 1995 are associated with change in cereal harvesting methods. Methods Twelve areas of machair on the Uists and Benbecula were re-surveyed in 2002, after previous surveys in 1983 and 1995. These and other areas of suitable habitat on these islands, plus Berneray, Baleshare, Vallay, Barra and Vatersay, were surveyed in 2003–05 to provide a breeding population estimate for the Western Isles. Cereal strips in the 12 core survey areas were mapped in 2002 and the timing and method of harvesting of each was recorded. Cattle-feeding stands in 24 crofting townships were visited in March 2003 to record the type of fodder available, measure grain abundance and ripeness in fodder samples, and record foraging Corn Buntings. Experimental trials tested whether Corn Buntings selected fodder with riper grain. Results The Western Isles Corn Bunting population was estimated at 117 occupied territories in 2005, a decline of 17% since 2002/03, and of at least 62% since 1995. Population decline was greater in areas with higher proportions of the cereal area harvested as arable silage. Arable silage contained fewer and less-ripe grains than traditionally harvested cereal, and was less likely to attract feeding Corn Buntings. Corn Buntings preferred to feed on silage containing riper grain. Conclusions The remaining Corn Bunting population of the Western Isles is declining rapidly, probably because of reduction in winter grain supply caused by change from traditional reaper-binder harvesting and stacking of fully ripe cereals to harvesting the crop as unripe or partially ripe arable silage. Management change to restore a supply of ripe grain over winter is likely to be essential if this population decline is to be halted and reversed.

Analysis of weed abundance in winter wheat sown at different times

The following conclusions may be drawn from the experimental data: 1. in wheat area sown with high number of germinating seeds, weed abundance shall be low at spring, i.e. the number of weed species characteristic of cereals shall be little; 2. this trend is increasing with the advance in sowing time, the number of species keeps decreasing; 3. at the beginning of May, the germinating weeds of species T4 appear, and the frequency of these weeds indicates the weed abundance at harvest time and the composition of stubble vegetation; 4. weeds of species G1 and G3 are abundantly shooting (primarily from rhizomes) in the stubble vegetation,; 5. in cereal areas, the weed survey made at late spring and in stubble in one calendar year shall give information about the full composition of weed species characteristic of the area; 6. by identification with GIS, the change of weed species can be followed within the field.

Effects of decoupling on land use: an EU wide, regionally differentiated analysis

This paper presents a quantitative analysis of the impacts of the „Luxembourg Compromise” as compared to a continuation of Agenda 2000 to the year 2010. The employed new version of the CAPRI model allows us to represent the different member states’ implementations of the CAP reform and to reflect endogenous world market prices based upon a spatial global trade model. The specific contribution of the analysis is a detailed look at the impacts of national differences in the CAP implementation and regional production structures with respect to changes in land allocation. At EU level, cereal areas decrease by about 5% and oilseeds by about 3%. This is paralleled by increases in the set-aside acreage and extensive fodder production. However, significant differences at the regional level can be observed. They are caused mainly by differences in the shares of durum wheat and fodder maize.

Models for spring migration of two aphid species Sitobion avenae (F.) and Rhopalosiphum padi (L.) infesting cereals in areas where they are entirely holocyclic

Abstract1 Cereals can be attacked severely by the grain aphid, Sitobion avenae (F.), and the bird cherry‐oat aphid, Rhopalosiphum padi (L.). The time of migration from winter hosts in spring is important regarding input to decision support systems concerning insecticide treatment of aphids.2 The present study aimed to construct two separate migration models, which could be used immediately for advisors and farmers but also be part of a decision support system for the chemical control of aphids in winter wheat and spring barley.3 Winter wheat (Triticum sativum Lam.) and spring barley (Hordeum vulgare L.) fields were monitored from 1991–2005 for the occurrence of grain aphids and bird cherry‐oat aphids, and the data were used to construct migration models.4 The models were constructed based on all 9 years data and subsequently validated by using all 9 years data, excluding 1 year at a time.5 The migration model for the grain aphid producing the best forecast was obtained with migration date M (number of days from 1 June), degree‐days (DD) of April (Ta) and DD of May (Tm), with the model being M= 265.0 − 10.2 loge(Ta) − 35.1 loge(Tm).6 The migration model for the bird cherry‐oat aphid producing the best forecast was obtained with migration date M (number of days from 15 May), DD of April (Ta) and DD from 1–15 May (Tm1), with the model being M= 294.4 − 34.7 loge(Ta) − 22.5 loge(Tm1).7 The models only worked well in areas where the grain aphid and the bird cherry‐oat aphid are entirely holocyclic.

Nutrient discharge from small agricultural catchments in Sweden

Abstract Within the Swedish Monitoring Programme for Agriculture, 27 small agricultural catchments were investigated for between 9 and 14 years (6 years for one catchment), starting in the late 1980s, to determine the impact of agricultural activities on discharge water. The catchments represent major variations in climate, soil types and farming in Sweden and hence long-term average load of total nitrogen (N) and total phosphorus (P) at stream outlets varied widely among the catchments, from 2 to 41 and from 0.1 to 0.9 kg ha −1 yr −1 , respectively. Catchments with large N loads were characterised by several factors favourable for leaching, such as mild winter climate, large precipitation, sandy or organic soils and high animal density in combination with intensive cropping systems with a low percentage of ley. Large P loads were mainly related to factors such as clay and clay loam soils, medium to high precipitation and large proportions of annual crops in the catchments. Flow-normalised time series of monthly loads of nitrate N, phosphate P and particulate P (for 24 catchments) were tested for trends. Significant downward trends were revealed for nitrate N, phosphate P and particulate P for seven, eight and three catchments, respectively, whereas, upward trends were revealed for nitrate N and particulate P for one and two catchments, respectively. Downward nitrate N trends for two catchments were correlated to smaller amounts of applied manure, especially during autumn, and to a decrease in the area of spring cereals and spring rape.

Cereal area and nitrogen use efficiency are drivers of future nitrogen fertilizer consumption.

At a global scale, cereal yields and fertilizer N consumption have increased in a near-linear fashion during the past 40 years and are highly correlated with one another. However, large differences exist in historical trends of N fertilizer usage and nitrogen use efficiency (NUE) among regions, countries, and crops. The reasons for these differences must be understood to estimate future N fertilizer requirements. Global nitrogen needs will depend on: (i) changes in cropped cereal area and the associated yield increases required to meet increasing cereal demand from population and income growth, and (ii) changes in NUE at the farm level. Our analysis indicates that the anticipated 38% increase in global cereal demand by 2025 can be met by a 30% increase in N use on cereals, provided that the steady decline in cereal harvest area is halted and the yield response to applied N can be increased by 20%. If losses of cereal cropping area continue at the rate of the past 20 years (-0.33% per year) and NUE cannot be increased substantially, a 60% increase in global N use on cereals would be required to meet cereal demand. Interventions to increase NUE and reduce N losses to the environment must be accomplished at the farm- or field-scale through a combination of improved technologies and carefully crafted local policies that contribute to the adoption of improved N management; uniform regional or national directives are unlikey to be effective at both sustaining yield increases and improving NUE. Examples from several countries show that increases in NUE at rates of 1% per year or more can be achieved if adequate investments are made in research and extension. Failure to arrest the decrease in cereal crop area and to improve NUE in the world's most important agricultural systems will likely cause severe damage to environmental services at local, regional, and global scales due to a large increase in reactive N load in the environment.

Serodetection of viruses associated to barley yellow dwarf (BYD) on cereals in Algeria

Surveys on viruses associated with Barley Yellow Dwarf (BYD) and their vectors were carried out in Algerian cereal areas (Guelma, Constantine, Algiers, Sidi-belabes, Adrar) in 1997 and 1998. Rhopalosiphum padi was present in all zones of culture, whereas R. maidis, Sitobion avenae, S. fragariae and Schizaphis graminum had only local distributions. In most areas BYD-like symptoms, i.e. dwarfing and yellowing of barley (Hordeum vulgare), dwarfing and reddening of oat (Avena sativa) and wheat (Triticum aestivum), were observed. Serological tests were done on these crops using DAS-ELISA (RMV and SGV) or TAS-ELISA using monoclonal antibodies specifie to CYDV-RPV or using different variant specifie BYDV-PAV (CpA and CpB) and BYDV-MAV monoclonal antibodies. BYDV-PAV was prevalent and few plant samples carrying RMV, SGV, BYDV-MAV or CYDV-RPV were detected. The relative frequencies of BYDV-PAV CpA and CpB serotypes were variable depending on the area and the crop season. The range of symptoms induced on barley by both Algerian BYDV-PAV CpB and BYDV-PAV CpA serotypes was mild to severe. Twenty-one BYDV-MAV isolates were compared using monoclonal antibodies, which distinguish two serotypes of this virus. Only one serotype was detected. This same serotype is also the most prevalent in Europe.

The rhizosphere signal molecule lumichrome alters seedling development in both legumes and cereals

The stimulatory role of lumichrome, a rhizosphere metabolite, was assessed on the growth of legume and cereal seedlings. At a very low nanomolar concentration (5 nm), lumichrome elicited growth promotion in cowpea, soybean, sorghum, millet and maize, but not in common bean, Bambara groundnut and Sudan grass. In soybean and cowpea only, 5 nm lumichrome caused early initiation of trifoliate leaf development, expansion in unifoliate and trifoliate leaves, increased stem elongation and, as a result, an increase in shoot and plant total biomass relative to control. Lumichrome (5 nm) also increased leaf area in maize and sorghum, and thus raised shoot and total biomass but there was no effect on the leaf area of the other cereals. Root growth was also stimulated in sorghum and millet by the supply of 5 nm lumichrome. By contrast, the application of a higher dose of lumichrome (50 nm) depressed development of unifoliate leaves in soybean, the second trifoliate leaf in cowpea, and shoot biomass in soybean. The 50 nm concentration also consistently decreased root development in cowpea and millet, but had no effect on the other species. These data show that lumichrome is a rhizosphere signal molecule that affects seedling development in both monocots and dicots.

New risks and opportunities for food security : scenario analyses for 2015 and 2050

the number of undernourished people in the developing world and the increasingly complex risks to food security, policymakers are faced with an enormous agenda. Freeing people from hunger will require more and better-targeted investments, innovations, and policy actions, driven by a keen understanding of the dynamic risks and forces that shape the factors affecting people's access to food and the links with nutrition. The International Food Policy Research Institute's (IFPRI's) International Model for Policy Analysis of Agricultural Commodities and Trade (IMPACT) provides insight into the management of these risks through appropriate policy actions. By projecting future global food scenarios to 2050, IMPACT explores the potential implications of policy action and inaction in several main risk areas as well as the effects on child malnutrition in the developing world, commodity prices, demand, cereal yields, production, and net trade. In the progressive policy actions scenario, which assumes increased investment in rural development, health, education, and agricultural research and development, developing country governments and the international community are able to dramatically reduce the number of food-insecure people, leading to a worldwide decline in hunger. Under these conditions, Latin America and China are able to virtually eliminate child malnutrition by 2050. Bolstered by the development and dissemination of improved technologies and better infrastructure, crop production and yields increase in developing countries. Notably, the bulk of the growth in production is driven by yield increases rather than by expanding land area. Spurred by growth in the agricultural sector, average incomes in developing countries increase. Rising incomes bolster demand for high-value agricultural products, such as meat, dairy, and fruits and vegetables; global livestock production more than doubles, for example. Average per capita calorie supplies for developing countries exceed 3,400 per day, well in excess of minimum requirements. The policy failure scenario assumes greater political discord and more extensive agricultural protectionism, together with the failure of policies to deal with food emergencies related to conflict. Slow growth and trade restrictions lead to stagnation in average per capita calorie availability, which remains only slightly above minimum requirements until after 2030, when availability increases. In addition, crucial investments in agriculture, rural development, and poverty reduction are forgone or displaced. Because of limited investment in agricultural research and technology, this scenario has a high level of crop area expansion as a result of relatively rapid population growth and slim yield improvements in developing countries. This scenario also results in flat maize prices, declining per capita cereal demand, falling beef prices, and relatively flat meat demand. As a result of the policies in this scenario, the number of malnourished children in developing countries rises between 1997 and 2015, after which there are only modest declines. In the technology and natural resource management failure scenario, yield growth falls even more than under the preceding scenario, forcing farmers to move into marginal producing areas, which causes a more rapid expansion of cereal area into less productive land that does not compensate for the yield shortfalls (and causes environmental degradation). As a result, cereal prices rise substantially through 2030 and then fall off only gradually. Beef and other meat prices, which are affected by the price of feed, follow a similar pattern. Developing-country per capita calorie availability is essentially unchanged over 1997–2050 and remains at a barely adequate average level. Given unequal access to the food that is available, millions of people actually consume less than the minimum. The occurrence of child undernourishment is even higher than under the policy failure scenario in all developing-country regions. Overall, the technology and natural resource management failure scenario results in the worst impact on food security and child malnourishment in the developing world. The progressive policy scenario outlines several of the most crucial positive steps. National governments and the international community must assume a new focus on agricultural growth and rural development, along with increasing their investments in education, social services, and health. Policies to encourage synergistic growth in the nonfarm sectors are also needed to spur broad-based economic growth. Underpinning these strategies and research agendas must be a firm commitment to reducing hunger and improving the welfare of the world's undernourished people. From Authors' Executive Summary

Metabolism Energy and Viscosity in Response to Cold and Tropical Cereals Area in Leghorn Pullets

Environmental aspects could influence metabolism energy and viscosity of cereal in poultr y nutrition. Four cereals seeds includes Alvand wheat, Makoie barley (as a cold cereals area), Chamran wheat and Karoun barely (as a tropical cereals area) in Iran were tested for measuring metabolize energy and viscosity. First experiment was arranged by 25 mature rooster using Sibbled methods to examine the metabolize energy. In the second experiment different percentage of cereals in 9 treatments (20 and 40% of Alvand and Makoie wheat and barley respectively) and (20 and 40% Chamran and Karoun, wheat and barley respectively) were used with control diets. The digesta of small intestine viscosity was recorded in the end of this experiment. No significant differences (P>0.05) was observed in gross energy (GE). Apparent metabolism energy (AME), apparent metabolism energy corrected by nitrogen (AMEn) True metabolism energy (TME) and TMEn were significantly higher in wheat than both types of barley. Significant increased (P<0.05) was found in this reflection in AME of Alvand and chamran wheat than both type of barley. In contrast, similar reaction was shown in AMEn, TME and TMEn of Chamran wheat compared with Karoun barley. The lowest significant value (P<0.05) was found in Makoie barley in this respect. There were no significan t differences (P<0.05) between feed intake (FI) and feed conversation ratio (FCR) for all treatments. Corresponding with high level of fiber in karoun and Makoie barley, significantly higher (P<0.05) viscosity was observed in karoun barley than other seed. The result of this study has shown that there was a significantly lower (P<0.05) metabolism energy in Makoie barley as a cold cereal area as well as higher viscosity compared with other examined cereals. This was corresponding with high significant (P<0.05) viscosity and high fiber content of cereal.

Effects of climate and land use on the occurrence of viruliferous aphids and the epidemiology of barley yellow dwarf disease

Abstract Barley yellow dwarf (BYD) disease is one of the most severe viral diseases in autumn sown cereals. In Western Europe, crop losses are mainly due to the PAV species of BYD viruses transmitted by Rhopalosiphum padi , the most abundant aphid in autumn. The proportion of migrant winged aphids that carry viruses in autumn is considered a major epidemiological factor for determining the disease incidence. In the main French cereal areas, during a 6-week period in autumn 1999–2002, the proportion of viruliferous R. padi assessed using a TAS-ELISA technique was on average of 4.98% (range 2.01–9.91%). Variations according to trap location were correlated with land use at the regional scale, annual variations being correlated with the climate of the year. Implementations of these results to improve BYD disease management program are discussed.

The Effect of Tropical and Cold Cereals Area on Leghorn Performance

3 Abstract: The nutritive value of cereal as a major ingredient of poultry feeding may be affected by environmental condition. This reflection may influence poultry production particularly egg production. One hundred and eighty Leghorn pullets were placed in individual cages. They were divided into 9 treatments, four in 20 and 40% of Alvand wheat and Makoie barley (as a cold cereal area). Next four in Chamran wheat and Karoun barley with the same percentage (as a tropical cereal area) were used with control diet. Chemical composition was similar in examined cereal with exception in barley fiber which was higher than others. There were no significant differences in body weight (BW), feed intake (FI) and feed conversation ratio (FCR) between cold and tropical cereal area as well as control diet. Egg weight and eggshell thickness were significantly higher (P<0.05) in the control diet compared with the other treatments. The similar trend was appeared in the yolk color (P<0.05). Haugh units were significantly greater (P<0.05) in 20% of Karoun barley as well as in 20% of Alvand wheat compared with other reflections. On the other hand no significant differences were observed in the egg production, egg shell weight, albumin height and specific gravity in treatments. The result of this study has shown that overall Leghorn performance had similar reaction in response to tropic and cold cereal area with exception in 40% of Karoun barely, which reduced this potential.

Long-term patterns in European brown hare population dynamics in Denmark: effects of agriculture, predation and climate

BackgroundIn Denmark and many other European countries, harvest records suggest a marked decline in European brown hare numbers, a decline often attributed to the agricultural practice. In the present study, we analyse the association between agricultural land-use, predator abundance and winter severity on the number of European brown hares harvested in Denmark in the years 1955 through 2000.ResultsWinter cereals had a significant negative association with European brown hare numbers. In contrast to this, root crop area was positively related to their numbers. Remaining crop categories were not significantly associated with the European brown hare numbers, though grass out of rotation tended to be positively related. The areas of root crop production and of grass out of rotation have been reduced by approximately 80% and 50%, respectively, while the area of winter cereals has increased markedly (>70%). However, European brown hare numbers were primarily negatively associated with the number of red fox. Finally, we also found a positive association between mild winters and European brown hare numbers.ConclusionThe decline of Danish European brown hare populations can mainly be attributed to predation by red fox, but the development in agricultural land-use during the last 45 years have also affected the European brown hare numbers negatively. Additionally, though mild winters were beneficial to European brown hares, the increasing frequency of mild winters during the study period was insufficient to reverse the negative population trend.

Use of nutrient balances for environmental impact calculations on experimental field scale

Nitrogen (N) leaching was analyzed in relation to nutrient use efficiency, N balance, and mineral N content in the soil in different crop rotations. In spring in the field occupied by sugar beet mineral nitrogen content was 87.8±10.9 kg N ha −1 per year, and after harvest there was a decrease to 46.0±15.7 kg N ha −1 per year. In the fields under winter and spring grain crops, these values were 102.6±54 and 80.5±32.8 kg ha −1 per year, respectively in spring, and 76.0±46.1 and 79.6±34.9 kg N ha −1, respectively, after harvest. The highest leaching from the fields where sugar beet and grain crops were grown was from 7.3 to 39 kg N ha −1 per year, compared to 2–17.1 kg N ha −1 per year from fields with perennial grasses in the rotation. The leaching from sugar beet fields was attributed to mineralization of large amounts of organic residues (tops and small roots) left in the field after harvesting. The quantity of organic matter left after harvesting sugar beet was 2480–7270 kg dry matter (DM) ha −1, compared to barley harvest (490–1150 kg DM ha −1) or winter wheat harvest (1890–2270 kg DM ha −1). The most negative N balance during the 5-year period was in the field with perennial grasses with a total of −426 kg N ha −1. The highest positive balance was for the field with sugar beet in the rotation (+174 kg N ha −1). In the field where cereals dominated the surplus of N was +74 kg N ha −1. Agronomic efficiency (AE) calculated as the ratio between DM yield and amount of fertilizer applied was calculated for main crop groups as well as for the investigated crop rotations with different crop structure. For whole rotations the highest AE was for sugar beet (23.4 kg DM (kg N) −1) followed by winter cereals (8 kg DM (kg N) −1), while the spring cereal yield response to N fertilization was equal to zero. The highest yield response (151 kg DM (kg N) −1) was observed in the rotation where sugar beet comprised 40%, grain crops 40%, and grasses 20% of the rotation period. AE was 42.5 kg DM (kg N) −1 in the rotation with 60% sugar beet and cereal plus leguminous grain crops 40% of the rotation and negative in the 100% grain crop rotation. In summary, the lowest environmental impact in terms of N leaching was in the rotation with grasses. AE was highest in the rotations where sugar beet was included and the area of spring cereals was reduced.

Priorities for mycotoxin research in Europe and the UK.

In the European Union the major concerns relating to mycotoxins are from aflatoxins in imported foods, and ochratoxin A and patulin in home-produced commodities. Whilst other mycotoxins such as deoxynivalenol do frequently occur, for example in cereals, they are not presently regulated and not regarded as a high priority. Commodities such as animal feed containing peanut meal, dried figs, pistachios and various spices from specific countries have from time-to-time presented problems and the approach has been to control imports through tough regulatory limits. To back-up these controls the EU has funded a multi-national project which developed and validated several mycotoxin methods for regulatory purposes. HPLC methods with good performance characteristics for aflatoxins, ochratoxin A and patulin at ng/g and sub-ng/g limits in a range of commodities were established. In Europe, ochratoxin A and patulin are two mycotoxins that contaminate home-produced products. Exposure to ochratoxin A has always been of some concern, and whilst there are a range of foodstuffs (cereals, meat products, dried fruit, coffee, wine and beer) that can give rise to that exposure, in the area of home-grown cereals there is the most scope to reduce contamination. In the UK and in Europe, research has focussed on what might be done to prevent or reduce ochratoxin A occurrence in cereals and to develop a HACCP approach to production, identifying and controlling mould growth and toxin formation. Factors such as cereal varieties, farming methods (cultivation and storage), pesticide treatments and the effect of climate are being examined in relation to mould and toxin occurrence. This paper reviews some UK and European funded mycotoxin projects covering the areas indicated above, and presents a view of priorities in the mycotoxin area.

Seasonal Patterns of Spore Dispersal of Phaeosphaeria spp. and Stagonospora spp.

The spatial and temporal patterns of discharge and dissemination of airborne spores of Phaeosphaeria spp. and Stagonospora spp. were studied. Both ascospores and pycnidiospores of the pathogens were deposited at various densities on microscope slides used as spore samplers. The maximum deposition of the spores was observed during the period of August to October. A multiple regression analysis was used to determine which weather factors significantly explained the variation measured in the numbers of ascospores that settled on microscope slides. Rainfall, air temperature, and relative air humidity were influential in the release of Phaeosphaeria spp. ascospores into the air. The amount of airborne ascospores was a function of the variables and remained largely under their control. The liberation of ascospores was favored by air temperature above 0°C, rainfall greater than 1 mm, and high relative humidity. The range of atmospheric conditions stimulating air dispersal of ascospores was wider than that for pycnidiospores. Pycnidiospores were sampled only during rainy days. Their release was affected adversely by air temperature below 5°C. Multiple regression models based on weather data were developed and verified for their predictive ability and accuracy by jackknife and cross-validation procedures, as well as by comparisons of observed and predicted mean numbers of deposited ascospores per microscope slide after a substitution of each period data set with a set of data of the other respective time interval. The numbers of airborne ascospores predicted by the regression models were in a good agreement with the observed values. The jackknife and cross-validation techniques allowed use of the limited data sets for both the parameter estimation and validation processes in a development of simulation models. The airborne inoculum appeared to be omnipresent over cereal areas year round, except during periods with freezing temperatures and a snow cover. Such an omnipresence of inoculum of the pathogens poses a danger to crops and could be of importance in the epidemiology of Stagonospora (= Septoria) blotches under the climatic conditions of central Poland.

Did tariffs stifle Spanish agriculture before 1936?

This paper challenges the widely held view that tariff protection was the major factor in explaining the poor performance of Spanish agriculture in the half century prior to the 1936 Civil War. After examining the general level of tariffs, it is argued that these were not sufficient in themselves to explain either the poor diets or weak demand for manufactured goods. Secondly, farmers were slow to switch resources out of cereals, not so much because of the tariffs, but rather because of the limited export opportunities for alternative crops, especially olive oil and wine. Finally, the evidence suggests that those areas which saw a significant increase in the area of cereals were just as likely to see a decline in the agricultural population as those that did not, suggesting that the rural exodus was determined by factors other than the tariff.

Occurrence and identity of Puccinia graminis on wheat, barley, andgrasses in Australia during summer - autumn 1992-93

Levels of stem rust (Puccinia graminis) in Australian wheat and barley crops were generally low from 1980 to 1992. Exceptionally wet conditions in South Australia (SA) during early summer 1992-93 resulted in the establishment of vast areas of self-sown cereals, in which stem rust increased rapidly. The disease was also more common in Western Australia during the summer months of 1992-93. Collections from rusted wheat, barley, and selected grass species were analysed in greenhouse tests using an array of differential cereal genotypes. Five pathotypes of P. graminis f. sp. tritici were recovered from SA, 3 of which had not been isolated over the previous 10 years in Australia and for up to 20 years in SA. The recurrence of these pathotypes highlights the need for caution in redeploying resistance genes for which virulence has not been detected for several years. The majority (79%) of isolates taken from stem-rusted barley in SA were either P. graminis f. sp. secalis or `scabrum" rust, both of which do not infect wheat. In total, 6 of 7 isolates of pathotype 21-2,7 recovered from SA came from stem-rusted barley, and as most wheats in this region are resistant to this pathotype, it appears that hosts other than wheat must be important in perpetuating such avirulent pathotypes.

Habitat selection and population size of Corn BuntingsMiliaria calandrabreeding in Britain in 1993

This paper presents the results of a survey of breeding Corn Buntings in Britain in 1993. Numbers of Corn Buntings and land–use types and field boundaries present were recorded by volunteers from over 1300 tetrads selected across the range of the species in Britain. The British breeding population was estimated at around 20 000 territories. Bootstrapped 95% confidence limits differed from the calculated estimates by approximately 20%. Population sizes in different regions of Britain were positively correlated with the proportion of total farmland under tillage and cereals and with the total areas of tillage and cereals, but not with the proportion of tillage made up by cereals nor with the overall area of farmland. Densities in occupied 10-km squares were lower in regions which experienced the greatest declines in distribution between 1968–72 and 1988–91. Areas abandoned by breeding birds between 1968–72 and 1988–91 were higher in altitude and held more grassland and less tilled land than areas where bird...