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1.
Niels P. Louwaars 《Euphytica》2018,214(7):114
Plant breeding collects, induces and rearranges genetic diversity followed by selection. Breeding may contribute to diversity in farmers’ fields or significantly reduce it. History has numerous examples of both. The diversity of many crops have gone through domestication, dispersal and modernization bottlenecks. Between these major decreasing processes, diversity has picked up through different evolutionary processes, and plant breeding affected by policies. Major negative effects of plant breeding on diversity have been recorded following the modernization bottleneck, but alternative breeding strategies have come up as well, both in the formal system and in the interphase between formal and farmers’ seed systems. Multiline breeding and participatory plant breeding are introduced as examples to also analyse effects of current developments in technology and policy. This paper intends to shed some light on the questions: how will current developments in technology and policy affect crop genetic diversity? Are we heading for a new bottleneck—either a molecular or a policy bottleneck, or a combination of both? Or could the future become more diverse? We look at the relationship between breeding, policies, and crop genetic diversity in farming systems with a birds-eye view. Notably because of current policy trends we warn for a new diversity bottleneck. 相似文献
2.
Pearl millet (Pennisetum glaucum [L.]R.Br.) is the staple food and fodder crop of farmers in the semi-arid areas of north-west India. The majority of farmer
sin western Rajasthan depend on their own seed production and employ different seed production strategies that involve different
levels of modern-variety introgression into landraces as well as different selection methods. This study quantifies the effects
of three seed management strategies on environmental adaptation and trait performance. Forty-eight entries representing farmers’
grain stocks — pure landraces or landraces with introgressed germ plasm from modern varieties — as well as 33 modern varieties,
multiplied by breeders or farmers, were evaluated in field trials at three different locations over two years under varying
drought-stress conditions. Results indicate that the plant characteristics employed by farmers in describing adaptive value
and productivity is an effective approach in discriminating the type of millet adapted to stress and non-stress conditions.
It was also found that introgression of modern varieties(MVs) leads to populations with a broader adaptation ability in comparison
to pure landraces or MVs alone – but only if MV introgression is practised regularly and is combined with mass panicle selection.
Under high-rainfall conditions, farmer grain stocks with MV introgression show similar productivity levels as modern varieties.
Under lessening rainfall, pure landraces show, in tendency, higher grain yields. In conclusion, farmers’ seed management could
form an integral part of participatory breeding programs.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
4.
Local seed systems and their importance for an improved seed supply in developing countries 总被引：5，自引：0，他引：5
Summary Varriety use and development, seed production and storage by farmers under local conditions, and seed exchange mechanisms are presented as the three principal components of a dynamic system that forms the most important seed source of food crops for small farmers in developing countries. The information on this topic is based on a literature review and a case study. Analysis of strengths and weaknesses of local seed systems leads to the conclusion that local seed systems and the formal system are complementary. Integrated approaches in breeding, and seed production and distribution show to have promising potential for improving seed supply for small farmers. 相似文献
5.
6.
Linking participatory plant breeding to the seed supply system 总被引：1，自引：0，他引：1
There is a strong link between formal plant breeding and seed supply. In developed countries, it was the emergence of systematic plant breeding that generated new named varieties and stimulated organized seed multiplication and marketing by commercial companies. In developing countries likewise, the experience of the ‘Green Revolution’ in the 1960’s led to the establishment in the following decade of national seed projects which could deliver the products of plant breeding more effectively from breeder to farmer. The provision of a secure conduit leading from research to agriculture remains a major justification for formal seed systems. The limitations of formal breeding approaches have been recognized in recent years, especially for crops grown in marginal and diverse environments, where farmers’ requirements are more complex. This has prompted interest in alternative participatory plant breeding strategies in which farmers can play an active role in the selection process. There has been a parallel recognition of the role of the informal seed sector, as the major seed supplier in many crops and areas where the regular sale of seed by formal organizations is difficult. The question which arise therefore is—“How do participatory breeding approaches relate to both formal and informal seed systems?” The purpose of this paper is to examine the technical, regulatory and policy aspects of this question, with emphasis on the following issues: The synthesis of this discussion is that PPB initiatives must be linked to a secure diffusion strategy within and beyond the participating communities if the technical and social benefits of this approach are to be fully realized. National policies relating to seeds and regulatory frameworks must also take account of this approach to avoid downstream constraints. 相似文献
- The nature and definition of participatory plant breeding (PPB) outputs,
- Maintaining the identity and integrity of PPB outputs
- The relevance of official variety evaluation and registration procedures
- Maximizing the diffusion and impact of PPB outputs
- Innovative seed supply systems linked to PPB activities
- The role of policy in facilitating alternative seed delivery systems
7.
It is widely recognized that conventional plant breeding has been more beneficial to farmers in high-potential environments
or those who can profitably modify their environment to suit new cultivars, than to the poorest farmers who cannot afford
to modify their environment through the application of additional inputs and cannot risk the replacement of their traditional,
well known and reliable varieties. As a consequence, low yields, crop failures, malnutrition, famine, and eventually poverty
still affect a large proportion of humanity. Participatory plant breeding (PPB) is seen by several scientists as a way to
overcome the limitations of conventional breeding by offering farmers the possibility to choose, in their own environment,
which varieties suit better their needs and conditions. PPB exploits the potential gains of breeding for specific adaptation
through decentralized selection, defined as selection in the target environment, and is the ultimate conceptual consequence
of a positive interpretation of genotype × environment interactions. The paper describes a model of PPB developed by The International
Center for Agricultural Research in the Dry Areas and used successfully in several countries in West Asia and North Africa.
Genetic variability is generated by breeders, selection is conducted jointly by breeders, farmers, and extension specialists
in a number of target environments, and the best selections are used in further cycles of recombination and selection. Technically,
the process is similar to conventional breeding, with three main differences. Testing and selection take place on-farm rather
than on-station, key decisions are taken jointly by farmers and the breeder, and the process can be independently implemented
at a large number of locations. The model also incorporates seed production. Farmers handle the initial phases, multiplying
promising breeding material in village-based seed production systems. The PPB model is flexible; it can generate populations,
pure lines, and eventually mixtures of pure lines in self-pollinated crops; as well as hybrids, populations, and synthetics
in cross-pollinated crops. PPB has several advantages. New varieties reach the release phase much faster than in conventional
breeding, and are better suited to farmers’ needs and willingness to invest in inputs and management. Release and seed multiplication
activities concentrate on varieties known to be farmer-acceptable. These advantages are particularly relevant to developing
countries where large investments in plant breeding have not yielded returns, and many “improved” varieties developed through
conventional breeding are not adopted by farmers. PPB also ensures that biodiversity is maintained or increased because different
varieties are selected at different locations. In addition to the economical benefits, participatory research has a number
of psychological, moral, and ethical benefits, which are the consequence of a progressive empowerment of the farmers’ communities;
these benefits affect sectors of their life beyond the agricultural aspects. In conclusion, PPB, as a case of demand driven
research, gives voice to farmers, including those who have been traditionally the most marginalized such as the women, and
elevates local knowledge to the role of science. 相似文献
8.
On-farm Conservation Strategy to Ensure Crop Genetic Diversity in Changing Agro-ecosystems in the Republic of Korea 总被引：2，自引：0，他引：2
Y.-J. Park A. Dixit K.-H. Ma J.-H. Kang V. R. Rao E.-G. Cho 《Journal of Agronomy and Crop Science》2005,191(6):401-410
With the recognition of certain limitations of ex situ methods for conservation of plant genetic resources the Convention on Biological Diversity (CBD) at the ‘Earth Summit’ in 1992 highlighted the importance of traditional knowledge of indigenous and local communities that are relevant for the conservation and sustainable use of biological diversity and gave considerable attention to on‐farm and other forms of in situ conservation. Unlike semi‐static nature of ex situ conservation the in situ or on‐farm conservation (OFC) is a dynamic evolutionary process. In developing countries like Republic of Korea, where there is a continuum between the use of traditional and modern cultivars, integration of OFC with already existing gene‐bank activities in the country will be an effective approach for conservation and sustainable use of the country's crop genetic resources. However, very little efforts have been made so far in developing strategies for OFC, therefore, in this paper we describe the importance of OFC and strategies for its development in Republic of Korea. Surveys over the last 20 years have shown that the landraces of major crops have been almost replaced by newly bred varieties in the country. But some vegetatively propagated or minor crop species are still being maintained in the farmers’ fields. We have identified crop landraces, which can be classified into four different categories from the OFC point of view. These are vegetatively propagated landraces, sexually reproduced landraces, landraces with improved varieties and landraces cultivated for the reasons of personal preference. The related issues on OFC including implementation methods from the point of national cooperative system in designated specific condition are also discussed to ensure the genetic diversity in the fast changing agro‐ecosystem of the country. 相似文献
9.
Subramani Pandian Karuppasamy Marichelvam Lakkakula Satish Stanislaus Antony Ceasar Shunmugiah Karutha Pandian Manikandan Ramesh 《Journal of Crop Science and Biotechnology》2018,21(5):469-481
Finger millet is an important staple food crop of semi-arid tropics also known as “super cereal” and has a higher calcium content than any other crops. Thousands of germplasm are being maintained and its genetic characterization is essential for further utilization in crop improvement. This research was performed to estimate the diversity and population genetic structure in the mini-core collection of finger millet by using SPAR markers, namely RAPD, ISSR, and DAMD markers. Altogether, 32 primers were used in this study, which produced 408 bands among which 344 were polymorphic. Analysis by combining all three marker systems revealed 84.31% of polymorphism among 90 genotypes of finger millet. Average polymorphism information content (PIC) produced by the ISSR, RAPD, and DAMD markers were 0.79, 0.81, 0.62, and average Rp values were 12.84, 8.17, and 8.53, respectively. The Jaccard's similarity value ranged from 0.233-0.861. IE 6059 and IE 5870 genotypes showed the highest Jaccard's similarity value of 0.861 in UPGMA analysis. Neighbor joining-based phylogenetic analysis produced two major clusters and the genotypes were grouped based on their geographical region of origin. Principal component analysis and principal coordinates analysis also confirmed the results. In population STRUCTURE analysis, the genotypes were divided into two subpopulations (P1and P2). These results confirmed that the genotypes we have assessed were genetically diverse and were clustered based on their geographic region of origin. The information obtained from this study will be useful in population management strategies and selection of genotypes for an effective breeding program in the future. 相似文献
10.
This paper considers the process of Participatory Varietal Selection (PVS) and presents approaches and ideas based on PVS
activities conducted on upland rice throughout Ghana between 1997 and 2003. In particular the role of informal seed systems
in PVS is investigated and implications for PVS design are identified. PVS programmes were conducted in two main agroecological
zones, Forest and Savannah, with 1,578 and 1,143 mm of annual rainfall, respectively, and between 40 and 100 varieties tested
at each site. In the Savannah zone IR12979-24-1 was officially released and in the Forest zone IDSA 85 was widely accepted
by farmers. Two surveys were conducted in an area of the Forest zone to study mechanisms of spread. Here small amounts (1–2 kg)
of seed of selected varieties had been given to 94 farmers. In 2002, 37% of 2,289 farmers in communities surveyed had already
grown a PVS variety and had obtained seed via informal mechanisms from other farmers, i.e. through gift, exchange or purchase. A modified approach for PVS is presented
which enables important issues identified in the paper to be accommodated. These issues include: utilising existing seed spread
mechanisms; facilitating formal release of acceptable varieties; assessing post-harvest traits, and; the need for PVS to be
an ongoing and sustainable process. 相似文献
11.
利用A-PAGE研究谷子籽粒蛋白质多态性 总被引：3，自引：0，他引：3
研究谷子贮藏蛋白多态性对谷子品种选育和鉴定评价具有重要的意义。本文利用A-PAGE方法对来自不同生态区的24份谷子品种籽粒的水溶蛋白、盐溶蛋白、酸溶蛋白和醇溶蛋白的多态性进行了研究。结果发现,不同谷子品种之间籽粒水溶蛋白、酸溶蛋白谱带相似,基本没有差异;每个谷子品种的盐溶蛋白谱带有20多条,仅有4个品种出现多态性谱带,多态性也较低。说明谷子品种水溶蛋白、盐溶蛋白和酸溶蛋白A-PAGE谱带不适用于谷子鉴定研究。谷子醇溶蛋白谱带存在一定的异质性,每个品种有7~10条醇溶蛋白谱带,其中5条为公共条带,2~5条为多态性谱带,醇溶蛋白A-PAGE谱带可以作为谷子品种鉴定评价的依据。结果说明,和玉米、小麦等禾谷类作物相比,不同生态区谷子栽培品种蛋白质变异较小,遗传背景变化较小,因此需要不断丰富谷子品种的遗传基础,为谷子品种选育提供更加丰富的材料。 相似文献
12.
Elaine McElhinny Eduardo Peralta Nelson Mazón Daniel L. Danial Graham Thiele Pim Lindhout 《Euphytica》2007,153(3):373-384
Summary Field trials were carried out in Ecuador with two indigenous communities, Ninín Cachipata and La Esperanza, to determine farmers’
preferences for quinoa (Chenopodium quinoa Willd.) cultivars and to improve PPB processes. More women than men participated, reflecting that quinoa, a primarily subsistence
crop, is mainly managed by women. Farmers’ field selection criteria for quinoa in the field were mostly based on yield, earliness
and plant colour; however only breeders’ measurements of yield and panicle height significantly correlated to farmer selection
scores. Older women gave higher scores than younger women or men, apparently due to a concept of no cultivar being without
value. Working in same gender pairs improved evaluation richness. INIAP technicians were more discriminating in their evaluations
than farmers. They also used additional selection criteria of disease resistance and uniformity. At seed selection, farmers
from Ninín Cachipata, where food security is not assured, chose lines based on yield, while farmers from La Esperanza, where
resources are less limiting, also considered seed size, colour, saponin content and marketability. Field characteristics were
not taken into consideration at seed selection, signifying that farmers are less interested in those characteristics, or that
it was difficult for them to correlate field data when presented in tabular form with seed characteristics. Future trials
with small farmers should have fewer lines or replications to avoid farmer fatigue during evaluation. Farmers who grow primarily
for subsistence in semi-arid environments have more interest in growing quinoa, and more to gain from having improved cultivars;
therefore future participatory efforts should focus on them. 相似文献
13.
Summary The diversity of cassava was studied in 10 communities spanning a range of socio-economic circumstances and located in the
four main agro-ecological zones in Ghana. On average, each farmer grew about two cultivars, mostly landraces, both for home
consumption and sale of the storage roots. In total, 35 differently-named landraces were mentioned, 26 in only single communities.
Most communities had grown cassava for > 100 years and seem to have acquired an additional landrace about every decade. Landraces
were also abandoned. The attributes mentioned of newly-acquired landraces were generally the reverse of landraces abandoned
and most were related to the storage roots. All the current landraces in all the communities seem to have been obtained from
other communities. None of the almost 300 interviewed farmers understood the role of pollination in setting seed and providing
variation amongst seedlings, none purposely planted seeds and most farmers ignored or weeded out cassava seedlings. However,
some did use planting material (stem cuttings) from self-sown seedlings, often when planting material from their crops was
scarce, and some purposely grew cuttings from a few such seedlings, apparently as experiments. That many seedlings were both
reported and seen in newly-planted crops suggests that some may be accidentally used as planting material, especially those
seedlings that are perceptually indistinct from the planted crop, resulting in polyclonal landraces. 相似文献
14.
Trygve Berg 《Euphytica》2009,166(3):423-430
Farmers’ seeds are most often lumped together in one broad category called ‘landraces’. But such a category covers variety
types that reflect different levels of farmer involvement. Those differences matters when we discuss such issues as genetic
erosion, on-farm conservation and seed related policies. The term landrace can be traced to the time when ‘modern’ varieties
of cereals were introduced to European farmers in the late nineteenth century. The farmers’ varieties of the time were called
‘landraces’ and understood as seeds adapted to local growing conditions through natural adaptation usually with no intentional
selection. But the term was quickly adopted as generic for all farmers’ varieties including those that are bred and maintained
by active seed selection on-farm. Such farmer-bred varieties are better termed ‘folk varieties’. The article discusses how
interaction of crop characteristics and developing technologies resulted in the evolution of crop varieties as either landraces
or folk varieties. It is argued that vulnerability to different agents of genetic erosion and feasibility of on-farm conservation
are clearly different for the two categories of farmers’ varieties. Likewise seed policies, particularly the issue of Farmers’
Rights would benefit from clarity of type of farmers’ varieties. 相似文献
15.
《分子植物育种》2007,5(2):155-155
The Generation Challenge Programme is a research and capacity building network that uses plant genetic diversity, advanced genomic science, and comparative biology to develop tools and technologies that enable plant breeders in the developing world to produce better crop varieties for resource-poor farmers. 相似文献
16.
农户杂粮生产关系到整个杂粮产业的粮食来源,目前农户是杂粮生产的主体,因此农户种植杂粮与否,将会影响社会杂粮的供给问题。为了分析当前农户种植杂粮的意愿及其影响因素,本研究以河北省337份杂粮种植户的调研数据为基础,利用SPSS统计软件,采用logistic模型回归分析方法,对农户杂粮种植意愿和影响因素进行分析。结果显示：愿意种植杂粮的农户占81.9%;农户年龄因素达到0.01极显著水平,农户文化程度和杂粮产量两个因素达到0.05显著水平,种子费和是否有订单两个因素达到0.10显著水平。最后提出继续增加科研水平,开展品种、技术、机械等方面的研发和推广;鼓励年轻、有文化的技术人员从事杂粮农业生产;加强技术培训工作;完善经营主体的补贴制度和企业农户订单制度等。 相似文献
17.
Pascal P. Okwiri Ojwang’ Rob Melis Josephine M. Songa Mwangi Githiri Charles Bett 《Euphytica》2009,170(3):383-393
Common bean (Phaseolus vulgaris L.) is the most important legume crop in Kenya. It is cultivated across a wide range of agro-ecologies which include high
potential and marginal areas. Eastern Kenya alone, largely semi-arid, accounts for 35% of the country’s total bean production.
Bean farmers mainly small-scale have limited access to quality seed, chemical pesticides and fertilizer. Therefore, bean yield
under on-farm conditions still remains below 500 kg ha−1 while the potential is about 1,200 kg ha−1 under semi-arid conditions. To asses the farmers’ views on bean varieties and a key insect pest and associated constraints
contributing to yield loss, research was undertaken. The research included survey to quantify the yield loss and Participatory
Rural Appraisal to determine the level of adoption and criteria for variety choice in semi-arid eastern Kenya (SAEK). The
results show that farmers consider drought and insect pest problems as main causes for low yields. The adoption rate for improved
varieties is high but self sufficiency in beans stands at 23% in the dry transitional (DT) agro-ecology and at 18% in the
dry mid-altitude (DM) agro-ecology, respectively. This could be attributed to low adaptability since most of the improved
varieties grown were selected for high potential areas but now found in marginal areas. Drought, earliness, yield stability,
and insect pest resistance are the main reasons for choice of varieties by farmers. Bean fly (Ophiomyia sp.) was identified as one of the key crop pests of beans limiting yield. Besides, African bollworm (Helicoverpa armigera) and bean aphid (Aphis fabae) were ranked higher. Due to limitations of the conventional breeding approach, a participatory plant breeding approach is
suggested so as to provide an opportunity to develop insect pest resistant varieties adapted to the SAEK region. 相似文献
18.
Farmers' seed management practices open up new base populations for pearl millet breeding in a semi-arid zone of India 总被引：2，自引：0，他引：2
K. Vom Brocke T. Presterl A. Christinck E. Weltzien R. H. H. Geiger 《Plant Breeding》2002,121(1):36-42
Farmers in western Rajasthan (north‐west India) produce and maintain their landrace populations of pearl millet through their own distinct seed management practices. The objective of this study was to characterize morphological and agronomic variability of different traits between and within three farmers' populations using quantitative‐genetic parameters. Populations examined were a typical landrace and two modified landraces, which were generated through farmer introgression of modern varieties with different levels of subsequent selection. From these three populations, 100 random full‐sib progenies were evaluated in field trials at two locations in western Rajasthan over two years. Significant genetic variation existed within the three populations. Estimates of heritability were moderate to high for all observed traits. Predicted selection response for grain yield across environments was 1.6% for the typical landrace and 2.2% for both the modified landraces. Results suggest that the introgression of modern varieties into landraces had increased the genetic diversity. Therefore, farmers' current breeding activities could open up new resources for plant breeding programmes aiming at plant improvement for the semiarid zones of India. 相似文献
19.
Nature and magnitude of genetic diversity was assessed using Mahalanobis's D2 statistics and canonical analysis in 50 genotypes of soybean grown in monoculture and in association with maize. All the genotypes were grouped in 10 clusters in case of monoculture, while 8 clusters were formed for intercropping. Monoculture was more suitable environment for expressing the genetic diversity than intercrop. Some genotypes had consistently the similar clustering pattern in both the cropping systems, while others were affected by the cropping system in expressing the genetic diversity. This was confirmed by the canonical analysis. Days to flowering and maturity, seed yield/plant, plant height and 100-seed weight were mainly responsible for genetic diversity in monoculture. Besides phenological traits, pod length and width, and seed yield/plant exerted marked influence on the genetic diversity of soybean genotypes grown in association with maize. Geographical distribution was not necessarily reflected by the genetic divergence, though some degree of relationship between geographic diversity and genetic diversity was evident under both the cropping systems. The performance of some genotypes varied from cropping system to another, while that of others remained unaffected. Breeding programmes to develop varieties suitable for sole crop, intercrop and both the cropping systems have been suggested. 相似文献
20.
J. A. Manu-Aduening R. I. Lamboll G. Ampong Mensah J. N. Lamptey E. Moses A. A. Dankyi R W. Gibson 《Euphytica》2006,150(1-2):47-61
Summary A participatory breeding programme involving farmers in two Ghanaian communities and scientists from CRI (Ghana) and NRI (UK) to develop superior cassava cultivars is described. Initial situation analyses of the communities indicated that cassava is increasing in importance both as a food and a cash crop. Most farmers utilised landraces of cassava; modern varieties were scarcely mentioned. Seeds of 16 half-sib families obtained from a crossing block in Nigeria at the International Institute of Tropical Agriculture were planted in a field in each community. During seedling and subsequent clonal generations, accessions selected either by farmers or scientists were retained to the next generation. This selection process has identified 29 superior accessions from amongst 1350 original seedlings. Farmers were relatively consistent in their selection from year to year and their selections corresponded with their stated criteria. Official variety release requires additional multilocational and inspection trials and postharvest assays but otherwise seems harmonious with a participatory breeding approach; our early involvement of farmers may facilitate early release, an important factor in cost-effectiveness. A stakeholder workshop confirmed the need for improved markets for cassava; surveys of current and potential markets have led to field trials with cassava processors. Adoption of a participatory approach, with farmers and scientists taking on new roles and decentralisation of activities, implies a concomitant transfer of influence and resources. 相似文献