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- Crop and Weed Ecology (2)
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- R.T.M. Chakanda (1)
- X. Cuesta Subía (1)
- J.C. Dawson (1)
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- T.J.L. Hintum van (1)
- Th.J.L. Hintum van (1)
- C. Kik (3)
- E. Lammerts Van Bueren (1)
- Y.E.E. Madodé (1)
- A.R. Monteros (1)
- R. Nijland (1)
- A.M. Osman (2)
- A. Palmé (1)
- S. Pino (1)
- E. Serpolay (1)
- S.P. Singh (1)
- M. Tesfaye (1)
- M.H. Thijssen (1)
- R. Treuren van (1)
- A. Tsegaye (1)
- L. Visser (1)
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- A.C. Zeven (2)
On the sustainable use and conservation of plant genetic resources in Europe. Report from Work Package 5 “Engaging the user Community” of the
Frese, L. ; Palmé, A. ; Kik, C. - \ 2014
NordGen - 34
duurzame landbouw - plantenveredeling - landrassen - rassen (planten) - geografische verdeling - genetische diversiteit - gewassen - genetische bronnen van plantensoorten - wilde verwanten - europa - sustainable agriculture - plant breeding - landraces - varieties - geographical distribution - genetic diversity - crops - plant genetic resources - wild relatives - europe
PGR Secure project , a collaborative project funded under the EU Seventh Framework Programme, THEME KBBE.2010.1.1-03, 'Characterization of biodiversity resources for wild crop relatives to improve crops by breeding', Grant agreement no. 266394."
Potato quality traits: variation and genetics in Ecuadorian potato landraces
Cuesta Subía, X. - \ 2013
University. Promotor(en): Richard Visser, co-promotor(en): Ben Vosman; Christian Bachem. - S.l. : s.n. - ISBN 9789461734945 - 197
solanum tuberosum - solanum - aardappelen - landrassen - wilde verwanten - kwaliteit - ideotypen - genetische variatie - kwantitatieve kenmerken - veredelingsprogramma's - plantenveredeling - genetische bronnen van plantensoorten - ecuador - potatoes - landraces - wild relatives - quality - ideotypes - genetic variation - quantitative traits - breeding programmes - plant breeding - plant genetic resources
Keeping local foods on the menu: a study on the small-scale processing of cowpea
Madodé, Y.E.E. - \ 2012
University. Promotor(en): Tiny van Boekel; D.J. Hounhouigan, co-promotor(en): Anita Linnemann; Rob Nout. - S.l. : s.n. - ISBN 9789461734358 - 176
vignabonen - voedselverwerking - landrassen - antinutritionele factoren - verteerbaarheid - west-afrika - benin - cowpeas - food processing - landraces - antinutritional factors - digestibility - west africa
Agriculture plays a significant role in the economy of most African countries. Yet malnutrition and micronutrient deficiencies occur regularly. Concomitantly, many carbohydrate rich staple foods and meat products are dumped on the African market and compet strongly with local products. The present thesis studied the potential of indigenous resources and locally developed practices to supply culturally acceptable and nutritious foods to African resource-poor people, using cowpea as model crop. This research is implemented using an interdisciplinary approach, which comprised plant breeding, food science and technology, human nutrition and social sciences. This thesis reports the findings of the research on food science and technology.
This study aimed to (i) characterise cowpea landraces in use in Benin with regard to nutritional, anti-nutritional and functional properties; (ii) determine present cowpea processing methods and eating habits with special reference to the content of cowpea dishes in available iron, zinc and calcium; (iii) assess the effect of the use of alkaline cooking aids on amino acids of cooked cowpea, and (iv) assess the impact of processing techniques on the flatulence generated by the intake of cowpea foods.
The genetic, nutritional and technological characterisation of cowpea landraces in use in Benin showed that a high level of similarity among unpigmented landraces as opposed to pigmented landraces. The cluster of unpigmented landraces significantely differed from the pigmented landraces for their fibre (24 vs. 56 g/kg, d.w.) and phenolics (3 vs. 8 g/kg, d.w.) contents as well as their seed size (200 vs. 139 g/1000 seeds, d.w.) and water absorption capacity (1049 vs. 1184 g/kg, d.w.).
An inventory of 18 cowpea dishes was obtained, which are produced by the combination of the following main unit operations: cooking, dehulling, deep-fat frying, steaming, roasting and soaking. Fermentation and germination are unusual technological practices in West-Africa. Consumers mainly consume Ata, Atassi and Abobo. These dishes contain little available iron because their [phytate] : [iron] molar ratio is above the required thresholds for a good iron uptake by the human body. The incorporation of cowpea leaves in certain dishes resulted in appropriate available iron and calcium potentials.
The constraints to cowpea processing were identified as: their long cooking time, the tediousness of the dehulling process and the perishability of beans and dishes. The local answer to the long cooking time is the use of alkaline cooking aids. These alkaline salts and the applied cooking conditions did not induce any significant change in the amino acid composition of pigmented landraces. Moreover, the toxicity potentially associated with this practice was not confirmed as no lysinoalanine could be quantified while using up to 0.5 % (w/v) of alkaline cooking aids.
Flatulence was indicated as the main constraint to cowpea consumption. Cowpea hulls are usually pointed as the main responsible for flatulence. In this research, galactose-oligosaccharides that are indigestible for humans and cause flatulence formation were not found in cowpea hulls. Fermentation wih Rhizopus or Bacillus bacteria reduced significantly the fermentability of cowpea in vitro and in vivo as compared with traditional processes.
The present study demonstrates the opportunities to improve the quality of cowpea dishes by the incorporation of the leaves and the possibilities to sustain the consumption of cowpea by focusing on soaking and/or fermentation processes.
Potato landraces: description and dynamics in three areas of Ecuador
Monteros, A.R. - \ 2011
University. Promotor(en): Richard Visser; Ben Vosman; Ronald van den Berg. - [S.l.] : s.n. - ISBN 9789461731401 - 160 p.
solanum - potatoes - wild relatives - landraces - solanum tuberosum subsp. andigena - solanum phureja - plant genetic resources - genetic diversity - genetic erosion - disease resistance - phytophthora infestans - aardappelen - wilde verwanten - landrassen - genetische bronnen van plantensoorten - genetische diversiteit - genetische erosie - ziekteresistentie
This thesis aims to fill the gap of information on the potato landrace diversity present in farmer fields of Ecuador. Passport data from previous collections (1970’s and 1980’s) were used to identify Carchi, Chimborazo and Loja as representative areas of potato diversity. The status of on-farm conservation in these three selected areas is covered in Chapter 2. Microsatellites (SSRs) helped us to describe the genetic relationships among the landraces found in these areas (Chapter 3). The characterization of potato landraces with respect to late blight resistance (Chapter 4) and quality traits (Chapter 5) complement the description.
Previous reports suggested loss of potato diversity (genetic erosion) in Ecuadorian farmer fields, but our collection of a total of 174 landraces showed that these areas still hold a substantial amount of potato landrace diversity (Chapter 2). More potato landraces were found in Chimborazo and Loja than previously sampled in the 70’s and 80’s. A comparison between the two collections, in each of the three areas, indicated only a small overlap in landrace names suggesting that the sampling of local landraces was far from exhaustive, both during the 70’s and 80’s and during the present collection trips. This is further supported by the fact that the diversity fair, which was organized after our collection trips in Chimborazo, resulted in many new landraces.
Surveys and farmer meetings in the study areas were used to describe the landrace-holders and the characteristics of the farming system they use. Mostly elderly people and small-scale farmers are currently maintaining potato landraces. These farmers look for income alternatives besides agriculture, resulting in migration. The vulnerability of the potato conservation varies among our study areas. In Carchi younger farmers demonstrate a lack of interest in cropping potato landraces. In Loja farming is not seen as the only sustainable source of income and there is a perceived lack of support from the government for the activities necessary to maintain local landraces. In Chimborazo farmers are culturally more attached to their land and see agriculture as a family activity, rendering the potato landrace conservation less vulnerable. Externally driven on-farm conservation interventions, such as diversity fairs or re-introduction of landraces, were highly appreciated by the farmers and could help to conserve the potatoes.
Diploid, triploid and tetraploid potato landraces are found in farmers fields. The material sampled at the three areas shows a high allelic diversity. At the tetraploid level (the most abundant) this was comparable to the variation present in an European collection of more than 800 varieties. More alleles are expected to be found when more material from other areas will be screened. There was no clear grouping of material collected according to study region, suggesting extensive movement of seed potatoes all over Ecuador.
A comparison of the application of variety names with the genetic relationships among potato landraces can result in either under- or over-estimation of the variability present in farmer fields (Chapter 3). In a number of cases landraces with identical common names proved to be genetically different or individual collection samples were actually a mixture of two landraces, pointing at under-estimation of diversity present. On the other hand, cases that might lead to over-estimation were also evident, e.g. genetically identical material was present under different names.
Our sampling of genetically different landraces for late blight (LB) resistance characterization (Chapter 4) confirmed that there was some variation for this trait among the landraces. Most of the landraces were susceptible to moderately resistant, but also some landraces with field resistance were identified. The observed field resistance was comparable to that in the widespread improved variety Fripapa. Possible strategies to improve late blight resistance in potato in Ecuador could include the identification of accessions with resistance among the local landraces, although only a few accessions may be expected to present field resistance. The introduction of new sources of resistance from other origins is a more viable alternative. One could attempt to introduce novel R-genes in material that already contains some level of quantitative resistance.
We found varying levels of dry matter, total polyphenol and total carotenoid contents among Ecuadorian potato landraces, some were comparable to the improved varieties. Based on the dry matter content most of the Ecuadorian landraces evaluated were suitable for processing as French fries or chips. The total polyphenol content of these potatoes were quite similar to those reported by the International Potato Center (Peru) for a set of accessions representing more than 60% of the variability in their potato collection. The total carotenoid content values of the Ecuadorian potatoes included in our study were similar or lower compared to previous studies on improved or Andean potatoes. The identified outstanding potato materials could be used to develop new potato varieties through plant breeding.
In Chimborazo and Loja farmers select landraces mainly based on their nutritional characteristics. However, in Carchi farmers prefer commercial improved varieties. Farmers´ preferences include empirical valuation of potato-quality rather than specific knowledge on nutritional characteristics of these potatoes.
This thesis provides important knowledge about the potato landraces in Ecuador. Our results can serve as the basis for further description and use of Ecuadorian native potatoes by breeders and local communities.
Vers bloed voor spinazie (interview met C. Kik)
Nijland, R. ; Kik, C. - \ 2011
Resource: weekblad voor Wageningen UR 5 (2011)22. - ISSN 1874-3625 - p. 8 - 8.
spinazie - genetische bronnen van plantensoorten - genenbanken - wilde verwanten - spinacia - zaad verzamelen - landrassen - bladgroenten - spinach - plant genetic resources - gene banks - wild relatives - seed collection - landraces - leafy vegetables
Chris Kik van het Centrum voor Genetische Bronnen Nederland (CGN) keerde afgelopen weekend terug van een eenmansexpeditie door Azerbeidzjan, Georgië en Armenië. Resultaat van de reis: een koffer volgepropt met 53 witte linnen zakjes zaad van wilde en lokaal geteelde spinazie. Dat materiaal gaat dienen als vers bloed voor de veredelingsbedrijven, maar, zo benadrukt Kik, het verzamelen ervan is ook belangrijk voor behoud van de biodiversteit.
Diversity of different farmer and modern wheat varieties cultivated in contrasting organic farming conditions in Western Europe and implications for European seed and variety legislation
Serpolay, E. ; Dawson, J.C. ; Chable, V. ; Lammerts Van Bueren, E. ; Osman, A.M. ; Pino, S. ; Goldringer, I. - \ 2011
Organic Agriculture 1 (2011)3. - ISSN 1879-4238 - p. 127 - 145.
rassenproeven - tarwe - triticum aestivum - biologische landbouw - landrassen - oude plantenrassen - rassen (planten) - west-europa - akkerbouw - variety trials - wheat - organic farming - landraces - old varieties - varieties - western europe - arable farming
The importance of genetic diversity in cultivated varieties for organic and low-input agriculture has attracted increasing attention in recent years, with a need to identify relevant sources of diversity and strategies for incorporating diversity in plant breeding for organic systems. However, the regulatory system in many countries, particularly in the European Union, restricts the varieties available to farmers to those registered in an official catalogue, and most countries require varieties to go through official tests under conventional management, which has resulted in a lack of suitable varieties available to organic farmers. This study characterized a sample of wheat (Triticum aestivum L.) landraces, historic varieties and varietal mixtures currently of interest to organic farmers in a diverse range of organic conditions on farms in Italy, France and the Netherlands. These varieties were assessed for individual plant and spike characteristics and compared to modern registered wheat varieties grown under the same on-farm conditions. Significant differences in mean values were found among varieties for many plant and spike traits, as well as significant variety-by-environment interactions. There were often similar levels of intra-varietal variability between farmer and modern varieties, indicating that the strong selection for genetic homogeneity to meet regulatory criteria has little impact on the phenotypic variability of certain traits when assessed on-farm. Several farmer varieties had high values of traits related to productivity outside their region of origin, which underlines the need for experimentation with diverse types of varieties in order to find and develop appropriate varieties for organic systems
Genetic erosion in crops: concept, research results and challenges
Wouw, M.J. van de; Kik, C. ; Hintum, T.J.L. van; Treuren, R. van; Visser, L. - \ 2010
Plant genetic resources: characterization and utilization 8 (2010)1. - ISSN 1479-2621 - p. 1 - 15.
genetische diversiteit - plantenveredeling - veredelde rassen - landrassen - genetische erosie - modernisering - genetic diversity - plant breeding - improved varieties - landraces - genetic erosion - modernization - spring bread wheat - oryza-sativa l. - allelic diversity changes - farmers seed selection - triticum-aestivum l. - microsatellite markers - molecular diversity - green-revolution - temporal trends - durum desf.
The loss of variation in crops clue to the modernization of agriculture has been described as genetic erosion The current paper discusses the different views that exist on the concept of genetic erosion in crops Genetic erosion of cultivated diversity is reflected in a modernization bottleneck in the diversity levels that occurred during the history of the crop Two stages in this bottleneck are recognized the initial replacement of landraces by modern cultivars, and further trends in diversity as a consequence of modern breeding practices Genetic erosion may occur at three levels of integration crop, variety and allele The different approaches in the recent literature to measure genetic erosion in crops are reviewed. Genetic erosion as reflected in a reduction of allelic evenness and richness appears to be the most useful definition, but has to be viewed in conjunction with events at variety level According to the reviewed literature, the most likely scenario of diversity trends during modernization is the following a reduction in diversity clue to the replacement of landraces by modern cultivars, but no further reduction after this replacement has been completed
Breeding initiatives of seeds of landraces, amateur varieties and conservation varieties : an inventory and case studies
Osman, A.M. ; Chable, V. - \ 2009
Driebergen [etc.] : Louis Bolk Instituut [etc.] - 35 p.
plantenveredeling - landrassen - conservering - veredelingsmethoden - plantenvermeerdering - plant breeding - landraces - conservation - breeding methods - propagation
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 report
Rice genetic resources in postwar Sierra Leone
Chakanda, R.T.M. - \ 2009
University. Promotor(en): Marc Sosef, co-promotor(en): Ronald van den Berg; Bert Visser. - - 161 p.
oryza - rice - plant genetic resources - genetic diversity - war - landraces - varieties - phenotypic variation - farming systems - sierra leone - farmers' knowledge - rijst - genetische bronnen van plantensoorten - genetische diversiteit - oorlog - landrassen - rassen (planten) - fenotypische variatie - bedrijfssystemen - kennis van boeren
This research presents the effect of the 10-year long civil war in Sierra Leone on rice genetic resources, using farmers and their seed systems in three selected districts as reference points. The war disrupted all forms of production and development in the country and like other sectors of the economy, agricultural production and the conservation of plant genetic resources at the farm level was severely affected. It emerged that farmers’ effectiveness to cultivate and manage their seed systems and the options to grow rice under insecure conditions were disrupted at different levels in the three districts studied. However, the general consequence of the war in all of the districts was that farmers lost considerable amounts of their seed stocks. Total losses for some rice varieties was averted because of the occurrence of a number of varieties in more than one village in the same region, which was a result of farmers seed exchange systems, and also due to farmer movement during the war. The majority of the varieties that were reported lost were actually “dispersed” in the regions, indicating good options for post-war recovery.
There was little evidence that the genetic composition of rice varieties were significantly altered as a consequence of the war, except for the total loss of upland varieties in one of the districts. The varieties that had the highest survival were those that had wider pre-war distribution, showed plasticity in growing habits wherein they demonstrated the potential to grow in both agro-ecosystems and in the different districts, and the fact that they existed in many different forms.
Statistical analysis showed a clear distinction between upland and lowland varieties, which demonstrated the effectiveness of farmer selection with regard to the two production ecosystems. This was different for the periods defined as pre-war and post-war. Pre-war varieties were less well defined in this respect. Further to this, there was evidence of a change in rice genetic resources between the pre-war and post-war situations, which was demonstrated in the number of varieties for each of the two ecosystems. Despite these changes, and the losses in seed stocks as a consequence of the war, genetic diversity increased in post-war rice varieties.
AFLP results indicated that rice varieties in Sierra Leone possess different levels of intra-variety variation, which makes it difficult to identify homogenous genotypes at the seed unit level. This was attributed to genetic exchanges caused by farmers’ practices of growing different varieties in mixtures. The variation however does not alter the profile of inter-variety genetic differences, which remains large enough to distinguish one variety from the other. It demonstrates that the genetic composition of rice varieties remains distinct from one another, and that variety names in Sierra Leone are good indicators for genetic diversity of rice at the farm level.
Farmers, seeds and varieties : supporting informal seed supply in Ethiopia
Thijssen, M.H. ; Bishaw, Z. ; Beshir, A. ; Boef, W.S. de - \ 2008
Wageningen : Wageningen International - ISBN 9789085852155 - 347
zaadproductie - zaden - bedrijfssystemenonderzoek - rassen (planten) - gewassen - genetische bronnen van plantensoorten - in-situ conservering - informele sector - landrassen - genetische diversiteit - conservering - ethiopië - landbouw bedrijven in het klein - seed production - seeds - farming systems research - varieties - crops - plant genetic resources - in situ conservation - informal sector - landraces - genetic diversity - conservation - ethiopia - peasant farming
Ethiopia is characterized by an enormous diversity in agro-ecosystems, crops and varieties, with the informal seed systems dominant in seed supply for almost all crops. The book addresses strategies and approaches through which professionals can support informal seed supply, and links these with the conservation and use of the huge genetic resource base of crops and local varieties. The book looks at informal seed supply from a number of different angles, introduces key concepts and strategies, and presents case studies from Ethiopia and other countries. It deals with the technical aspects of, quality and availability of, and access to seed, and of supporting informal supply. It also deals with the role of farmers in the conservation and management of local crops and varieties, and the participation of farmers and communities in plant breeding and research. It takes a particular interest in the role of farmer organizations in seed supply, and how this role can be strengthened by developing community and small-scale seed enterprises. The aim of all the strategies, case studies and reflections on experiences presented in this book is to improve the availability of and access to quality seeds and varieties, thereby improving the livelihoods of small-scale farmers in Ethiopia and beyond.
Population genetics of traditionally managed maize : farming practice as a determinant of genetic structure and identity of maize landraces in Mexico
Heerwaarden, J. van - \ 2007
University. Promotor(en): Richard Visser; Fred van Eeuwijk. - [S.l.] : S.n. - ISBN 9789085048626 - 138
zea mays - maïs - landrassen - genetische diversiteit - genetische erosie - landbouw bedrijven in het klein - populatiegenetica - modellen - transgene planten - mexico - maize - landraces - genetic diversity - genetic erosion - peasant farming - population genetics - models - transgenic plants
A large amount of crop genetic diversity is being maintained in farmers' fields worldwide. The population genetics of traditionally managed landraces is therefore of interest to the conservation of genetic resources. The growing trend towards agricultural modernization and the prospect of introducing genetically modified varieties into centers of origin have increased the need to understand the determinants of genetic structure in landraces of our basic food crops. Patterns of genetic diversity are known to be affected by environmental and geographic factors, but there has been an increasing interest in the role of farmers. Recent years have seen work on both genetic differentiation between seedlots, as well as on the agricultural practices that are expected to influence this differentiation. Unfortunately, few studies have been able to link observed patterns of differentiation to farming practice. The lack of a proper analytical framework has probably contributed to this omission. The population genetics of landraces is complex, with many human and environmental factors affecting the distribution of genetic variation. In this thesis, we aim at achieving a better understanding of the processes that underlie the genetic structure maize landraces in their centre of origin, Mexico. We combine a wide range of theoretical and empirical methods in order to provide explanations for observed patterns of genetic structure. In addition, we use these tools to predict some present and future consequences of seed management by farmers on the genetic identity of landrace populations. In chapter II, we present a metapopulation model that accounts for several features that are unique to managed maize populations. We developed a coalescence-based model of a metapopulation undergoing pollen and seed flow as well as extinction in the form of seed replacement. Unlike previous models, our model treats seed migration as episodic-, partial replacement from a single source rather than as constant immigration from the entire metapopulation. We showed that this particular form of migration leads to novel results. Contrary to classical predictions, within-deme coalescence time was not invariant to the amount of migrating seed. Genetic structure had a parabolic relationship to the amount of migrating seed instead of showing the expected exponential decrease. In contrast, the effects of seed migration frequency on diversity and structure were in line with classical predictions. We concluded that is impossible to describe seed migration by a single parameter. Genetic structure was shown to depend on deme size when the amount of migrant seed is large. Extinction decreased or increased genetic structure depending on the level of migration and number of demes. Finally, we demonstrated that higher levels of pollen migration can mask the effects of seed management. This model provides an important first step in our ability to understand the effects of farming practice on the population genetics of maize landraces. In chapter III, we study the joint role of the environment and humans as determinants of genetic differentiation. We present results on the hierarchical genetic structure in a sample of seedlots in highland and lowland environments in central Mexico. Within-and between village Fsl and Qsl values were used as measures of neutral and agronomic genetic differentiation respectively. We developed and used a new computer model to predict Fst in the two environments on the basis of data on local seed management practice and planting patterns. Strong genetic differences were found between highland and lowland maize, for both markers and traits. Three highland villages planted maize of admixed origin, as evidenced by both molecular markers and phenological traits. This suggested that human mediated gene flow from lowland to highland environments has taken place. Molecular differentiation was low for molecular markers but was notably higher in the lowlands. Our model correctly predicted this difference based on lower pollen flow and smaller seedlot sizes in the lowlands. Agronomical traits showed higher differentiation between villages and were probably subject to diversifying selection. Phenological traits showed the strongest differentiation. Field data suggested that different planting dates may explain the observed differences. Phenological differentiation was highest in the transect containing the admixed seedlots, proving that genetic structure may result from the introgression of traits that diverged in a foreign environment. In chapter IV, we address the issue of genetic erosion in modernized subsistence agriculture. Genetic erosion is thought to occur when modern varieties replace traditional landraces. Actual proof of genetic erosion for any particular area or crop has been rarely found however. A complicating factor in the study of diversity loss in traditional agriculture is the often-noted coexistence between traditional and improved varieties. Moreover, adoption of modern varieties into the traditional seed supply system may blur the distinction between modern and traditional varieties. The inability to classify germplasm into discrete types makes it hard to measure diversity. We addressed these problems by means of a case study on modernized smallholder maize agriculture in southern Mexico. We characterized seedlots obtained from both farmers and commercial seed vendors, for agronomical traits and molecular markers. Farmer interviews were used to distinguish between traditional landraces and recycled modern varieties. We calculated genetic diversity, defined as the mean differentiation between individual seedlots, for different types of germplasm. Modem germplasm was clearly distinct from traditional landraces. Close resemblance between modem- and recycled modem varieties proved that despite years of independent evolution, recycled varieties have not diverged much from their ancestral stocks. We showed that different traits reveal different levels of relative diversity, demonstrating the inherent difficulty of assessing diversity loss. The group of recycled modem varieties presented the lowest diversity for all measured traits. We could therefore predict that complete replacement of landraces by these varieties will reduce diversity in the traditional seed system. Under current patterns of coexistence however, the distinctness of modem and traditional varieties caused only a limited reduction of genetic diversity. Chapter V. deals with the effects of reproductive and population genetic processes on the probability of detecting inadvertently introduced transgenes in maize landraces. This subject has become relevant since initial findings suggesting contamination of Mexican landraces with transgenes were followed by contradictory results in subsequent years. Theoretical and simulation results showed that certain aspects of maize reproductive biology negatively affect the detection probability. We demonstrated that the strongest potential limitation on detection was caused by the aggregated frequency distribution that is a consequence of farmer-mediated introduction of transgenes. Analysis of recent sampling efforts reveals that detection probabilities may be much lower than previously assumed, partly explaining the recent inconsistent results 123
Sweetpotato breeding for northeastern Uganda: farmer varieties, farmer-participatory selection, and stability of performance
Abidin, P.E. - \ 2004
University. Promotor(en): P. Stam; Paul Struik, co-promotor(en): Fred van Eeuwijk; E.E. Carey. - [S.l.] : S.n. - ISBN 9085040337 - 152 p.
ipomoea batatas - zoete aardappelen - plantenveredeling - germplasm - genetische bronnen van plantensoorten - biodiversiteit - genotype-milieu interactie - rassen (planten) - landrassen - rasreacties - uganda - sweet potatoes - plant breeding - plant genetic resources - biodiversity - genotype environment interaction - varieties - landraces - varietal reactions
On indigenous production, genetic diversity and crop ecology of enset (Ensete ventricosum (Welw.) Cheesman)
Tsegaye, A. - \ 2002
University. Promotor(en): Paul Struik. - S.l. : S.n. - ISBN 9789058086280 - 198
ensete ventricosum - ensete - teeltsystemen - genetische variatie - genetische merkers - random amplified polymorphic dna - klonen - landrassen - inheemse kennis - genetische bronnen - groei - verplanten - snoeien - gewasopbrengst - verliezen bij het oogsten - verwerking - voedselproductie - ethiopië - agro-ecologie - cropping systems - genetic variation - genetic markers - clones - landraces - indigenous knowledge - genetic resources - growth - transplanting - pruning - crop yield - harvesting losses - processing - food production - ethiopia - agroecology
<DIR><DIR><DIR><strong><p>Keywords</strong> : Enset, staple, indigenous knowledge, genetic diversity, AFLP, characterisation, conservation, Leaf Appearance Rate, Radiation Use Efficiency, yield potential, transplanting, leaf pruning, fermentation, 'kocho', food security</p><font size="4"><p> </p></DIR></DIR></DIR></font><p>The indigenous enset-farming complex of the south and southwestern highlands of Ethiopia has supported a higher population density than any other farming system. Enset ( <em>Ensete ventricosum</em> (Welw.) Cheesman) has been cultivated as (co-)staple food for about 7-10 million people. Since the last three decades, however, because of population pressure, recurrent drought and diseases there has been degradation of natural resources and, thus, the system failed to sustain the population. In the study, described in this thesis, the indigenous enset production methods, farm-based enset biodiversity and the plant characteristics and environmental factors influencing productivity were analysed to identify yield potentials and constraints in Sidama, Wolaita and Hadiya. The ultimate goal was to develop improved agronomic practices and enhance the use of the existing genetic diversity to reduce the gap between the actual yield and yield potential.</p><p> Some indigenous cultivation methods vary among regions: initiation of suckers, frequency of transplanting, leaf pruning and planting patterns. Morphologically diverse enset clones were identified in Sidama (52), Wolaita (55) and Hadiya (59). Among 146 clones, a total of 180 AFLP fragments was scored of which 104 (58%) appeared polymorphic. The AFLP-based dendrogram showed more duplication groups than the farmers' characterisation method suggesting that farmers overestimate the genetic diversity. The correlation between the two methods was only weak. Yet, the comparison between the AFLP-based and farmers-based characterisation methods showed that some aspects such as absence of clear regional clusters and clustering of clones with various prefixes to a single group corresponded well. Duplications in the clones identified by both methods may be safely removed from a conservation programme. Variation in farmers' skill in discriminating between clones may suggest that the areas where the people's culture is closely associated with the crop, should receive high priority for collecting clones or serving as sites for <em>in situ</em> conservation.</p><p> Plant height and LAI of different clones increased faster at Awassa or Areka than at Sidama because of a higher leaf appearance rate associated with temperatures being closer to the optimum. This led to higher early interception of photosynthetically active radiation and higher dry matter production. The mean extinction coefficient was between 0.56<FONT FACE="Symbol">-</font>0.91 and radiation use efficiency (RUE) ranged from 1.43<FONT FACE="Symbol">-</font>2.67 g MJ <sup><FONT FACE="Symbol">-</font>1</SUP>. Yield potential differences between clones existed, mainly because of differences in RUE. The average ratio actual yield : yield potential (0.24) suggest that much can be done to reduce the yield gap.</p><p> Transplanting suckers directly into permanent field shortens the period until maturity, provides a reasonable yield soon after removing the suckers from the mother corm and reduces the chance of attack by disease or pests. The partitioning of dry matter to the harvestable parts, the harvest indices at different states of processing and the losses caused by scraping or fermentation, however, became more advantageous as a result of repetitive transplanting. At flowering, harvest indices based on fermented enset products of once, twice and three times transplanted suckers were 0.20, 0.35 and 0.25, respectively. Leaf pruning or the interaction between leaf pruning and transplanting did not significantly affect dry matter partitioning, harvest index or processing losses.</p><p> The maximum fresh weights of kocho after fermentation from enset plants transplanted once, twice and thrice were respectively 25.9, 54.1 and 37.1 kg plant <sup><FONT FACE="Symbol">-</font>1</SUP>. In terms of weight and energy, enset is the most productive crop in the country, sweet potato is second, taro is third and Irish potato is fourth. The cultivation of enset in densely populated areas under low-input conditions can sustain the population better than that of any other crop. Moreover, enset produces various by-products and the prolonged presence of a closed canopy has an ecological advantage similar to that of forest.</p><p> This study combines indigenous technical knowledge, agronomic, physiological and molecular studies. It has contributed significantly to the understanding of the production methods and the genetic diversity. It has also investigated some strategies to reduce the gap between the actual yield and yield potential. Furthermore, it has underlined the relevance of physiological studies by generating basic physiological parameters. The information gained in this study also helped to underline future research topics.
Multidisciplinary approach in estimating genetic diversity of Ethiopian tetraploid wheat (Triticum turgidum L.) landraces = Multidisciplinaire benadering in het schatten van de genetische diversiteit van Ethiopische tetraploïde landrassen van tarwe (Triticum turgidum L.)
Tesfaye, M. - \ 2001
University. Promotor(en): Maarten Koornneef; J.H. de Jong; Ronald van den Berg. - S.l. : S.n. - ISBN 9789058084644 - 108
triticum turgidum - genetische diversiteit - tetraploïdie - triticum durum - landrassen - biodiversiteit - chromosoompolymorfie - genetic diversity - tetraploidy - landraces - biodiversity - chromosome polymorphism
</strong><p>This thesis presents a diversity analysis for 26 tetraploid wheat landraces from the central region of Ethiopia and four cultivars using five markers: morphological traits, chromosome portraits, microsatellites, AFLP and storage proteins.</p><p>The aim of the study is:</p><UL><LI>To estimate the magnitude of genetic diversity within and between 26 landraces</LI><LI>To identify the pattern of genetic diversity within and between geographical areas</LI><LI>To detect duplications within and between accessions</LI><LI>To prioritise markers used for estimating genetic diversity in Ethiopian tetraploid wheat landraces</LI></UL><p>The study revealed a great difference of diversity between the landraces and also demonstrated that the high variation is due to the within component of accessions rather than the between landrace component. No strong variation for genetic composition was observed between plants from different altitudes and subregions. An integrated application of morphological, chromosomal, molecular and storage protein markers for assessing biodiversity in these wheat landraces is strongly recommended.</p><p> </p></font>
Phenotypic variation in a core collection of common bean (Phaseolus vulgaris L.) in the Netherlands
Zeven, A.C. ; Waninge, J. ; Hintum, Th.J.L. van; Singh, S.P. - \ 1999
Euphytica 109 (1999). - ISSN 0014-2336 - p. 93 - 106.
fenetica - genenbanken - landrassen - bonen - phaseolus vulgaris - nederland - fenotypische variatie - phenetics - gene banks - landraces - beans - netherlands - phenotypic variation
Forty accessions, forming a core collection of mainly bush type of the common bean (Phaseolus vulgaris L.) germplasm in the Netherlands, were evaluated for 14 qualitative and quantitative traits at the Agricultural University, Wageningen (WAU), the Netherlands in 1992. These and an additional 117 Dutch accessions, mainly collected in private home gardens, were also evaluated for phaseolin seed protein pattern, and morphological and agronomic traits at the International Center for Tropical Agriculture (CIAT, Spanish acronym), Cali, Columbia between 1987 and 1997. Multivariate and principal component analyses at both WAU and CIAT indicated existence of one large group with no discernable patterns among Dutch common bean collections of landraces, garden forms and cultivars. However, when phaseolin, an evolutionary, biochemical marker, was used as an initial classification criterion followed by use of morphological markers, the two major gene pools; Andean and Middle American with two races in each (Chile and Nueva Granada in Andean, and Durango and Mesoamerica in Middle American) were identified
The introduction of the common bean (Phaseolus vulgaris L.) into Western Europe and the phenotypic variation of dry beans collected in the Netherlands.
Zeven, A.C. - \ 1997
Euphytica 94 (1997). - ISSN 0014-2336 - p. 319 - 328.
bonen - phaseolus vulgaris - landrassen - fenotypische variatie - beans - landraces - phenotypic variation
The first introduction of common bean from Central/South America into Western Europe most likely took place around 1500. The attractive bean seeds and their easy transportation warranted numerous additional introductions, not only from the Americas, but also from other areas where the common bean had been introduced. Bean seeds also must have been transported all over Europe both locally and internationally. Natural and human selection took place in and among introductions as well as in hybrid populations. Strong human selection may have led to pure garden forms which often occur in The Netherlands. In the period 1945–1948 a dry-bean collection of some 1500 accessions was made in The Netherlands. These have been classified into various criteria: 1. landraces, ‘primitive’ garden forms and cultivars, 2. (semi)climbing or bush types, 3. various seed colour types, including whitish, brownish, yellowish, black and variegated
Voederwortelen : I. de indeling en de beschrijving van het in Nederland geteelde assortiment
Wijbrans, J.R. - \ 1953
Euphytica 2 (1953)2. - ISSN 0014-2336 - p. 149 - 156.
voedergewassen - akkerbouw - penen - beschrijvingen - landrassen - rassenlijsten - fodder crops - arable farming - carrots - descriptions - landraces - descriptive list of varieties
Het sortiment van de in Nederland verbouwde voederwortelen vertoont een veelheid van vormen. Er is getracht deze te ordenen in een aantal duidelijk omschreven typen. Ten dele zijn deze typen te beschouwen als het gemiddelde beeld van enige naverwante vormen, ten dele dekken zij bestaande vormen. Er komt nog materiaal in de handel, waaraan weinig kweekwerk is verricht en dat wegens geringe uniformiteit soms moeilijk tot een of ander type is te rekenen