Breeding initiatives of seeds of landraces, amateur varieties and conservation varieties : an inventory and case studies

One of the objectives of the Farm Seed Opportunities (FSO) project is to develop on farm breeding methodologies for the conservation and development of landraces, amateur and conservation varieties. The starting point for the development of these methodologies are the already existing experiences of farmers, small scale seed producers and researchers. To be able to draw on the expertise of these practitioners, we have selected five breeding initiatives for in depth case-studies. Prior to the selection of the five cases we carried out an inventory of all known initiatives within the European Economic Area. Results are presented in this repor

Differences between spring wheat cultivars for emergence and early development after seed infection with Fusarium culmorum

Infection of wheat seeds with Fusarium spp. causes seedling blight. As a result of this disease, fields sown with infected seeds show a reduced plant density. This is especially a problem in organic agriculture, for which currently no practical seed disinfection methods are available. In the present project we investigated whether spring wheat cultivars differ in sensitivity to seedling blight, whether the possible differences could be linked to cultivar differences in early growth rates, and what size the delay in canopy closure resulting from the plant reductions was. Six spring wheat cultivars (Melon, Lavett, SW Kungsjet, Epos, Pasteur, Thasos), containing three infection levels (averages 5, 15 and 27%) of Fusarium culmorum were obtained and were sown in a field experiment in 2006 in 4 repetitions. Measurements included percentage of emergence, light interception and above ground dry matter to calculate relative growth rates. Infection of seeds with F. culmorum resulted in lower plant densities and a delay in time to 10% light interception of up to 5 days. First preliminary results also show that cultivars differ for sensitivity to seedling blight, and that cultivars with higher early growth rates appeared to be less sensitive to seedling blight, with the exception of cultivar Thasos. If future experiments confirm this relation, it could be used to select cultivars which are more resistant to seedling blight

Combined numerical and experimental investigation of transmission idle gear rattle

Gear rattle is caused by engine torsional vibration (engine order response) imparted to the transmission components, further causing the gears to oscillate within their functional backlashes. These oscillations lead to the repetitive impact of gear teeth, which lead to noisy responses, referred to as gear rattle. The lack of in-depth research into the effect of lubricant on gear rattle has been identified as a deficiency in the previous research in rattle. The aim ofthe current work is to address this shortcoming. The thesis outlines a new approach in investigating the problem of idle gear rattle. The approach is based on the assumption that under idling condition the teeth-pair impact loads are sufficiently low and the gear speeds are sufficiently high to permit the formation of a hydrodynamic lubricant film between the mating gear teeth. This film acts as a non-linear spring-damper that couples the driver and the driven gears. A torsional single-degree of freedom model is used in the development of the theory. The model is then expanded into a seven-degree of freedom torsional model and finally into an Il-degree of freedom model that also includes the lateral vibrations of the supporting shafts. The Il-degree of freedom model is based on a real life transmission that is also used in experimental studies to validate the model. It is found that lubricant viscosity and bearing clearance (lubricant resistance in squeeze) play important roles in determining the dynamics of the system and its propensity to rattle. At low temperatures, the lateral vibrations of the shafts, carrying the gears interfere with the gear teeth impact action. The severity of rattle is determined by the relationship between the entraining and squeeze film actions of the hydrodynamic film. When the latter dominates, the system can rattle more severely. The numerical results are found to correlate well with the experimental findings obtained from vehicle tests in a semi-anechoic chamber and also with those from a transmission test rig in the powertrain laboratory

Effect of vernalization period and bulb size on bolting of onion cultivar “Texas Early Grano” grown under Gezira conditions, Sudan

     Texas Early Grano onion cultivar is very popular in Sudan and is used mainly as a salad vegetable. Unfortunately, this cultivar does not flower and produce seeds under Sudan conditions and seeds should be imported from abroad. Attempts to produce seeds of this cultivar under Gezira conditions have failed. Therefore, the objective of this research was to study the effects of bulb size and vernalization on the induction of flowering of Texas Early Grano onion cultivar. Experiments were conducted at the research farm of the Faculty of Agricultural Sciences, University of Gezira, Wad Medani, Sudan, during the  winter seasons of 2008/09 and 2009/10.   Treatments consisted of vernalization periods ranging from 45 to 180 days, storage temperatures of 4 to 50C, and bulb size which was small and medium. Treatments were arranged in a  randomized complete block design with three replicates. Results indicated that vernalization duration significantly affected emergence percentage. As vernalization duration increased, emergence percentage increased in both seasons. Bulb size had no significant effects on emergence percentage. Vernalization temperatures of 4 to 50C for 90 days or more was the key factor for the induction of bolting of Texas Early Grano cultivar. To obtain the highest bolting percentage and seed yield, a combination of venrnalization at 4 to 50C for 180 days and medium-sized bulbs should be recommended.       يعتبر صنف البصل "تكساس إيرلى جرانو" من الأصناف المعروفة في السودان التي تستخدم كأحد الخضر الرئيسية في طبق السلطة. محاولة إنتاج بذور هذا الصنف محلياً لم تعط نتائج إيجابية نسبة لعدم توفر درجات الحرارة المنخفضة اللازمة لتحفيز الإزهار تحت ظروف ولاية الجزيرة. لذا هدفت هذه الدراسة إلى تحفيز الإزهار لإنتاج البذور من هذا الصنف باستخدام ظاهرة الإرتباع (التخزين المبرد) لأحجام مختلفة من الأبصال. أجريت هذه الدراسة بمزرعة كلية العلوم الزراعية، جامعة الجزيرة، واد مدني، السودان خلال موسمي 2008/09 و 2009/10م. شملت التجارب فترات تخزين مبرد تراوحت ما بين 45- 180 يوما في درجات حرارة تراوحت ما بين 4 إلي 50 م ونوعين من حجم الأبصال (صغير ومتوسط).  استخدم تصميم القطاعات العشوائية الكاملة بثلاث مكررات. أشارت النتائج إلى أن التخزين المبرد في درجات الحرارة 4 - 5°م هو العامل الرئيسي المحفز للإزهار في صنف البصل "تكساس إيرلي جرانو". التخزين المبرد أظهر تاثيراً معنوياً في نسبة الانبات، فكلما زادت فترة التخزين المبرد زادت نسبة الانبات في كلا الموسمين، بينما لم يؤثر حجم الأبصال في نسبة الانبات. تم الحصول على أعلى نسبة للإزهار وإنتاجية البذور بزراعة الأبصال متوسطة الحجم والمخزنة في درجة حرارة 4 - 5°م لفترة 180 يوما. لذلك يوصى بتخزين الأبصال متوسطة الحجم في درجات حرارة تتراوح بين 4 - 5°م لفترة 180 يوما أو اكثر للحصول على بذور صنف البصل "تكساس إيرلي جرانو" تحت ظروف ولاية الجزيرة

Towards an improved variety assortment for the Dutch organic sector : case studies on onion and spring wheat

Key words: organic farming; principles of organic agriculture; food production chain; plant breeding; genetic correlation; plant traits; farmers’ preferences; variety testing; Value for Cultivation and Use; EU seed legislation; onion; Allium cepa; spring wheat; Triticum aestivum; baking quality Variety choice is an important component of organic crop management. The organic sector pursues to produce healthy, nutritious food without using synthetic inputs and excessive amounts of natural resources. Access to varieties that are able to cope with weeds, diseases and pests, and thrive well under an organic fertility management regime, allows actors in the organic food production chain to achieve these aspirations. In this thesis I analyse how the current breeding, variety assessment and registration process should be changed to provide varieties that fulfil the needs of organic farmers, traders and processors. The research is based on the cases of two crops, onion (Allium cepa) and spring wheat (Triticum aestivum), that differ in key issues that influence the options for change: breeding and variety registration aspects; organic seed and crop production issues; destination of the harvest; and composition of and relations between actors in the production chain. Variety trials, in which we evaluated onion and spring wheat varieties for traits prioritized by organic stakeholders, revealed that the variety assortment displayed important weaknesses when grown and processed organically. In the case of onion, farmers needed varieties with improvements for resistances against main diseases, root system, storability and erect plant types in combination with high yield. For spring wheat, weed suppressiveness and baking quality were the key traits that required improvements. Interviews with conventional onion breeders showed that they focussed on yield and post-harvest traits (storability, bulb quality). In addition to these traits, breeding for the organic sector would require breeders to pay more attention to the selection of field traits like partial resistance against leaf diseases and a better root system. To improve key traits for organic growers, selection should take place in a growing environment without the fungicides and herbicides that are typically applied in conventional nurseries. Interviewing conventional wheat breeders made clear that selection for the organic market would conflict with achieving the high yield demanded by conventional growers. Breeders have achieved high yields by increasing the harvest index, which goes at the expense of baking quality through a relative decrease in protein content. Based on a literature review, we propose two alternative approaches to improve yield and protein content simultaneously: selection for increased total biomass or/and selection for protein quality. The first approach would deliver taller, leafier varieties that are also more competitive against weeds. Improving protein quality would require selection under low nitrogen input or organic growing conditions as protein composition is strongly influenced by soil nitrogen availability. Analysis of data of our own conventional and organic variety trials, together with datasets from other European countries showed that for other important traits (e.g., yield, disease resistance, plant length) selection for the organic sector could also be conducted in non-organically managed breeding nurseries, which typically refrain from fungicides and growth regulator applications, as genetic correlations for these traits were high (0.8 -1.0). Conducting variety trials in organic fields and evaluating these for traits prioritized by the stakeholders make results more relevant for the latter. In the specific case of Value for Cultivation and Use (VCU) testing, that is part of the official variety registration procedure of field crops in the EU, adapting the research protocol proved crucial to provide market access to varieties better adapted to organic production. The organic spring wheat VCU testing resulted in the inclusion of varieties in an organic section of the Dutch Recommended List of Varieties, showing that the statutory variety testing system is flexible to address new needs. However, procedures are costly and not in proportion to market size and in this way prohibit the release of varieties for organic and other small markets. Although specifically wheat breeders proved to be open to consider adaptations in their programme, the relatively small market prevents conventional private sector breeders from investing in selecting varieties specifically targeted at the organic sector. Therefore we elaborate options to set up a way of breeding that is in line with organic principles and overcomes this economic barrier. </p

Lightly loaded lubricated impacts: idle gear rattle

Idle gear rattle is associated with the characteristic noise that unselected impacting gears radiate to the environment. It is induced by engine order vibration in the presence of backlash in the unengaged gear pairs, resulting in oscillatory response within their backlash range. A tribo-dynamic model of a front wheel drive manual transmission has been developed to study idle rattle, considering the hydrodynamic contact film reaction and flank friction. The model includes the torsional motions of the idle gears and the lateral motions of the supporting output shafts. The hydrodynamic lubricant film formed between the gear teeth under light impact loads behaves as a non-linear spring-damper mechanism, whilst the inclusion of the shafts’ bearing compliances introduces additional non-linear terms, which are modelled as piecewise linear functions. The aim of the paper is to demonstrate the effect of the lubricant on the system’s response, which is eventually transferred to the gearbox case through the bearings. The results are found to conform closely to experimental measurements taken from a vehicle equipped with a manual transmission of the same type

Gear teeth impacts in hydrodynamic conjunctions promoting idle gear rattle

The rattle phenomenon in vehicular transmissions and its impact on the automotive industry have been widely reported in the literature. A variety of palliative measures have been suggested for attenuation of rattle such as use of backlash eliminators, clutch dampers or dual-mass flywheels. These palliative measures incur further costs and can have untoward implications in powertrain noise and vibration problems. A fundamental investigation of the dynamics of impacting gears is undoubtedly the way forward for a root cause solution. This paper introduces a new approach for understanding the interactions between the transmission gears during engine idle conditions by taking into account the effect of lubrication. Gear impacting surfaces are treated as lubricated conjunctions rather than the usually reported dry impacting solids. Depending on load and speed of entraining motion of the lubricant into the contact domains, the regime of lubrication alters. In this paper, the influence of lubricant in torsional vibration of lightly loaded idling gears is examined which promotes iso-viscous hydrodynamic conditions. It is shown that the lubricant film under these conditions behaves as a time-varying non-linear spring-damper element. Spectral analysis of the system response is compared to the findings of the linearised system

Numerical investigation of two models of nonlinear fractional reaction subdiffusion equations

We consider new numerical schemes to solve two different systems of nonlinear fractional reaction subdiffusion equations. These systems of equations model the reversible reaction A+B⇌C in the presence of anomalous subdiffusion. The first model is based on the Henry \& Wearne [1] model where the reaction term is added to the subdiffusion equation. The second model is based on the model by Angstmann, Donnelly \& Henry [2] which involves a modified fractional differential operator. For both models the Keller Box method [3] along with a modified L1 scheme (ML1), adapted from the Oldham and Spanier L1 scheme [4], are used to approximate the spatial and fractional derivatives respectively. Numerical prediction of both models were compared for a number of examples given the same initial and boundary conditions and the same anomalous exponents. From the results, we see similar short time behaviour for both models predicted. However for long times the solution of the second model remains positive whilst the Henry \& Wearne based–model predictions may become negative

Effet de la coccidiose sur certaines composantes sanguines chez la chèvre

L'étude hématologique chez les chèvres atteintes de coccidiose montre un net abaissement du taux des érythrocytes et du volume de l'hémoglobine, également suivi d'un accroissement tant de l'hématocrite que du volume corpusculaire moyen des globules rouges. Il existe une nette éosinophilie avec une augmentation importante des éosinophiles et une augmentation moins marquée des lymphocytes et des monocytes. L'étude des protéines sériques montre leur accroissement tant dans le sérum que dans sa fraction albumine qui se maintient à un niveau constant à partir du deuxième jour après l'infection jusqu'à la fin des observations. L'analyse des composants minéraux du sérum a montré une augmentation considérable du potassium, avec abaissements sensibles des taux de sodium et de phosphore, probablement dus à la déshydratation ainsi qu'à l'inaptitude de l'épithélium intestinal à absorber ces minéraux à la suite de lésions locales dues à la présence de mérozoïtes coccidien