The diversity and sustainable development of crop genetic resources in the Lancang River Valley

This paper reviews the status of crop genetic resources in Yunnan province of China from 1978 to 1999. Results are presented of same research in the field of the diversity of cultivated and wild crop. Yunnan is one of the centre of origin or genetic diversity of more than 200 cultivated and wild crops. There are over 500 cultivated plants which account for over 80% of the total in China and more than 650 species of wild crops. In addition, there are more than 440 species of main wild flowers. According to our recently researches there are abundant species, subspecies and varieties of crop genetic resources in Yunnan Province. The Lancang River Valley is the richest genetic diversity centre of rice, maize, wheat, barley, buckwheat, legumes, ramie, sugarcane, vegetable, tea, actinidia and so on. For example, there are 59 varieties (including all varieties of Oryza sativa L. in China) in 5933 accession of Yunnan indigenous rice. The Lancang River Valley is one of the centre for genetic diversity of rice resources and a rich region for elite and rare rice resources of Yunnan, too. In order to protect the highly endangered crop genetic resources in the Lancang River Valley, it is necessary and very important to set up a collection, conservation, utilization and research system, enhancing their protection and utilization, in situ- and ex situ-conservation, farm management and sustainable production.     

Seed exchanges,a key to analyze crop diversity dynamics in farmer-led on-farm conservation

Sustainable management of genetic resources is a crucial issue in the global context of food security. On-farm conservation is now widely acknowledged as a relevant strategy to reach this goal because it maintains evolutionary forces within and between the different components of the agricultural system. Seed exchanges between farmers play a key role in this process but are complicated to study over different agricultural contexts. This review begins by illustrating how interdisciplinary approaches combining ethnobotany and genetics helps provide a detailed analysis of the role of social and genetic dynamic interactions related to seed exchanges in traditional farming systems with farmer-led on-farm conservation. Secondly, the evolution of crop genetic diversity management is described in the context of industrialized farming systems. We follow the evolution of crop biodiversity perception by involved actors using a socio-historical perspective. After the agricultural shift from a traditional to a productivist model, recent social developments such as citizen science and participatory research movements are emerging and are strongly concerned by the question of biodiversity. These emerging trends which recognize and value seed exchanges between farmers show similarities to farmer-to-farmer seed exchanges in traditional farming systems. To what extent are these systems comparable? To fully benefit from studies in both traditional and industrialized contexts, it will be critical to develop an interdisciplinary framework to rigorously compare seed exchange systems and more generally farmer-led on-farm conservation strategies in diverse agricultural systems.     

Farmers' practices, metapopulation dynamics, and conservation of agricultural biodiversity on-farm: a case study of sorghum among the Duupa in sub-sahelian Cameroon

In many traditionally managed agroecosystems, populations of domesticated plants maintain high levels of genetic diversity. The threat of erosion of this diversity is a current conservation concern, motivating studies of how diversity can be maintained by in situ conservation measures. Precisely how the biological traits of plants and the cultural practices of farmers act on fundamental evolutionary forces - drift, migration, selection, and mutation - to create and maintain crop plant diversity has been little investigated in detail. We develop some elements of the framework required for studying such biocultural interactions, focusing on one component of management: farmers' decisions on what to plant, and the structure of germplasm exchange among farmers. We illustrate the approach with a study of Duupa farmers in northern Cameroon. Our results suggest that sorghum populations managed by the Duupa function like source-sink metapopulations. Fields of older farmers, larger and containing a greater number of varieties, act as sources, whereas fields of younger farmers act as sinks, becoming sources as their owners mature. In each field, seeds for sowing are selected from a small number of plants. The frequent exchange of germplasm among fields may counteract the genetic bottlenecks associated with the small number of genitors within each field. Identifying key processes and key individuals should facilitate the design of in situ conservation measures to maintain crop plant diversity against the threat of genetic erosion.     

The unappreciated ecology of landrace populations: Conservation consequences of soil seed banks in Cassava

Failure to take into account the ecological complexity of landrace populations of crop plants limits our ability to conserve their genetic resources in situ. Soil seed banks are a central feature of the ecology of landrace populations of cassava; their existence has consequences for conservation. Seedlings recruited from seed banks are incorporated by farmers into their stocks of clones of this vegetatively propagated crop, transforming pure clonality into a mixed clonal/sexual reproductive system. Soil seed banks, and farmers’ responses to them, play an important role in maintaining diversity in populations of cassava landraces. In a study combining genetic and ethnobiological approaches, we showed the following: (i) Recruitment from soil seed banks increased diversity of populations at the local scale. At the level of a field, the presence of plants issued from seeds resulted in significantly greater diversity of genotypes and phenotypes than if only individuals planted by farmers had been present. (ii) Farmers’ use of seed banks has enabled indirect ‘exchange’ of locally adapted cassava germplasm between cultural groups, without requiring that groups actually encountered one another and engaged in social exchange of cultivars. (iii) Farmers have responded to catastrophic crop failure by using seed banks to regenerate stocks of clones. This use of seed banks should enable cassava populations to respond to disasters by an increase of genetic diversity, rather than by a narrowing of the genetic base, often feared in such situations.     

A case study of seed exchange networks and gene flow for barley (Hordeum vulgare subsp. vulgare) in Morocco

Local patterns of seed regeneration and trade that occur outside the formal breeding sector (seed exchange networks) can have a strong influence on the genetic diversity and evolution of traditional crop varieties. Despite this, little is known about the extent to which seed exchange networks influence gene flow and genetic structure in traditional crop varieties. Here we study barley (Hordeum vulgare subsp. vulgare) in rural communes of Northern Morocco in 2008 and 2009. We quantified seed regeneration and exchange by farmers within the seed exchange network using structured interviews. Using SSR markers, we also quantified the neutral genetic diversity and structure of a complex of traditional varieties referred to as Beldi that is managed in this exchange network. The majority of farmers (>88 %) report cultivating Beldi. Most seeds of Beldi (70–90 %) are maintained on-farm, while the remainder of seeds are obtained from local markets within the commune. Beldi has high genetic diversity and there is weak but significant genetic structure between communes (F_ST = 0.031). From SSR marker data there is evidence of a high level of gene flow between communes not reported in interviews. Seeds purchased in local markets likely represent seeds from a larger geographic region, leading to lower genetic structure among communes than expected based on the reported level of on-farm seed regeneration and local sourcing of seed. We discuss the implications of this seed exchange network for the conservation of traditional barley varieties in the study region.     

Indigenous knowledge and traditional conservation of hulless barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis>) germplasm resources in the Tibetan communities of Shangri-la,Yunnan, SW China

Hulless barley (Hordeum vulgare L. s. l.) is the staple food crop of Tibetan communities in the Qinghai-Tibet Plateau, covering Tibet, Qinghai, Gansu, Sichuan and Yunnan provinces in China. Participatory Rural Appraisal methodolgies were employed in twenty-seven villages that were randomly selected in Shangri-la region, or Diqing Prefecture of Yunnan Province to document the ethnobotanical and indigenous knowledge related to the production, diversity, use and conservation of hulless barley. For Tibetans in Shangri-la, the crop has a high socio-cultural value. The genetic diversity of landraces managed by the farmers in Shangri-la is an extremely important germplasm resource. We recorded a total of 54 landraces that are primarily described by farmers based on their cooking quality, growth cycle, color and size of the grains. The ethnobotanical and indigenous knowledge recorded in this study contributes to the understanding of the genetic diversity of hulless barley in Shangri-la and even in the Qinghai-Tibet Plateau, and in defining appropriate strategies for its conservation on farm.     

Farmers' valuation and conservation of crop genetic resources

This paper focuses on the value of landraces (traditional and local crop varieties) to farmers in centers of agricultural diversity. Additional information on the factors contributing to the private value which farmers assign to landraces may help to identify a strategy for ensuring the conservation of the crop genetic resources (CGRs) which are embodied in landraces while at the same time minimizing the costs. Economic and ethnobotanical approaches for examining the value of landraces complement one another. A formal economic approach establishes a framework for quantitative analysis while ethnobotanical methods provide qualitative data for assessing the likelihood that particular farmers or farm sectors will maintain landraces. Our research synthesizes the two approaches in order to examine farmer selection of local wheat landraces in relation to that of modern varieties in three provinces in western Turkey. Multiple farmer concerns (e.g. yield, risk, quality), environmental heterogeneity, and missing markets contribute to the persistence of landraces. Household characteristics informing variety choice will also affect the household's perceptions of the importance and value of landraces.     

Spatial and temporal dynamics in genetic diversity in upland rice and late millet (<Emphasis Type="Italic">Pennisetum glaucum</Emphasis> (L.) R. Br.) in The Gambia

Ambiguity exists about the level of genetic diversity represented by farmer crop varieties, how it develops over time and how it relates to the diversity comprised by formal varieties. As part of an interdisciplinary technological/sociological study on farmer management of gene flow, upland rice (Oryza sativa L.) and late millet (Pennisetum glaucum (L.) R.Br.) from The Gambia were investigated for morphological and molecular variation. The goal of these analyses was to obtain insight into the level of crop genetic diversity of farmer’s materials planted in several case study villages in The Gambia. For both crops, samples were collected from villages and various research institutes. Based on variety names, different rice and millet varieties were expected to be used in different villages. In fact, there was a large overlap in genetic diversity for both crops, masked by the use of synonyms. The considerable similarity in rice genetic diversity between villages most likely results from the exchange of varieties between farmers. For millet this seems the result of development of varieties from the same gene pool. Some farmer varieties of rice, however, are apparent hybrid forms between the species O. sativa and O. glaberrima Steud., and farmer varieties in general displayed higher levels of genetic diversity than formal varieties. This indicates that, for rice, genetic diversity develops in farmers’ fields and may have potential use in formal breeding programs.     

Economic concepts for designing policies to conserve crop genetic resources on farms

The future food supply of all societies depends on the exploitation of genetic recombination and allelic diversity for crop improvement, and many of the world's farmers depend directly on the harvests of the genetic diversity they sow for food and fodder as well as the next season's seed. On farm conservation is an important component of the global strategy to conserve crop genetic resources, though the structure of costs and benefits from on farm conservation differ from those associated with ex situ conservation in gene banks. A fundamental problem that affects the design of policies to encourage on farm conservation is that crop genetic diversity is an impure public good, meaning that it has both private and public economic attributes. This concept is defined and made operational in order to assist practitioners in identifying (1) least-cost sites for on farm conservation (2) the types of policy instruments that might be appropriate for supporting conservation once a site has been located. Published findings regarding prospects for on farm conservation as economies develop are summarized and empirical examples of suitable policies to support farmers' decisions are placed in the context of economics principles.     

Farmers’ adoption of maize (Zea mays L.) hybrids and the persistence of landraces in Southwest China: implications for policy and breeding

This paper examines changes in the distribution of maize hybrids and landraces in the mountainous areas of southwest China over 1998–2008, farmers’ reasons for cultivar adoption and the implications for national policies in relation to seed production and breeding, based on baseline data and a survey conducted in Guangxi, Yunnan and Guizhou. The study traced the dynamic changes in the adoption of hybrids and landraces in farmers’ fields, explored how individual farmer’s choices can influence local landrace distribution, and investigated the space for conducive policy and innovative action for on-farm conservation of maize genetic resources. The research showed that although there is strong farmers’ interest in accessing modern maize hybrids, farmers also express strong reasons for maintaining at least some of the landraces that satisfy local agronomic context and social preferences. Farmers recognized that hybrids have a number of advantages but they also indicated some disadvantages of the current available hybrids e.g. with respect to seed quality, local adaptability, taste and cost of seeds, but also lack of information on the performances of the new hybrids. Based on farmers’ reasoning and experiences, the requirements have been identified for improving yield combined with local preferences (agronomic, cultural and socio-economic). The paper concludes by identifying options for how China might seek to develop resilient seed systems for smallholder farmers in poor areas, under changing climatical conditions and volatile markets. Participatory Plant Breeding is among the options considered for bringing farmers’ needs into conservation and breeding strategies for improving local adaptation.     

黑苦荞米黄酮提取工艺优化及其降血糖活性研究

为了获得合适的黑苦荞米黄酮提取工艺,该文采用单因素试验和响应面设计,选择乙醇体积分数、料液比、提取时间、提取温度4个因素,优化黑苦荞米黄酮提取工艺。试验结果表明,黑苦荞米黄酮的最佳提取条件是:乙醇体积分数54%,料液比1:24 g/m L,提取时间62 min,提取温度71℃。在此条件下,理论黄酮得率为2.21%,实际黄酮得率为2.20%,相对误差为0.45%。在此基础上进一步研究了黑苦荞米黄酮的α-淀粉酶抑制活性,结果表明7.5 mg/m L的黑苦荞米黄酮对α-淀粉酶活性的抑制率为54.05%,与二甲双胍(5 mg/m L)效果相当;此外,与空白对照相比,50μg/m L黑苦荞米黄酮能显著(P0.05)提高肝脏细胞Hep G2的葡萄糖消耗量(48.73%),并促进肝脏细胞糖原的合成。研究结果表明,黑苦荞米黄酮具有较好的辅助降血糖功效。     

Analyses of the seed protein contents on the cultivated and wild buckwheat <Emphasis Type="Italic">Fagopyrum esculentum</Emphasis> resources

The seed protein contents of 179 accessions belonging to ten species of genus Fagopyrum were determined by means of the Kjeldahl method. The results indicated that there are significant differences of seed protein content among different accessions within the same species. The average protein content of F. esculentum is 12.94%, ranging from 8.81–18.71%, and the protein content of Sibano is the highest, up to 18.71%, Gantian 1 the lowest with 8.81%. The average protein content of tartary buckwheat is 12.17%, with the range from 7.82–18.94%, and the protein content of cultivated tartary buckwheat Qianku 2 is the highest (18.59%), and that of Ganku 1 (7.82%) the lowest. Moreover, there are significant differences of seed protein content among different buckwheat species and between the different buckwheat types (between common buckwheat and tartary buckwheat, between the diploid and the tetraploid, between the cultivated and the wild, and between the big-achene group and the small-achene group). The average seed protein content of F. giganteum is the highest in all tested species, up to 17.81% with the range of 13.91–21.27%, and that of F. callianthum the lowest, only 8.31%. This study was financed by the Natural Science Foundation of China (30270852, 30471116), Program for New Century Excellent Talents in University (NCET-2004-0913), Guizhou Key International Cooperation Project (Qianke Hewai G Zi 2005#400108), Guizhou Oversea Talent Project (Qianren Xiangmu Zizhu Hetong 2004#02), and Key Project of Students in Guizhou Normal University (GNU-SP-2005-SJXY-A01)     

Inferring seed exchange between farmers from population genetic structure of barley landrace Arabi Aswad from Northern Syria

Apart from their significance in genetic conservation, barley landraces are still favoured by local farmers in low-input farming systems. They often perform more predictably under adverse conditions than modern cultivars due to local adaptation. Increased seed exchange between farmers may put adaptation of local populations of barley landraces at risk. Isozyme markers were used to investigate differentiation and infer gene flow between local populations of barley landrace Arabi Aswad in Northern Syria. Inferred gene flow decreased exponentially with geographic distance and may imply that seed exchange between farmers is limited to a regional scale and diminishes over longer distance. Gene flow seems to be a suitable index for estimating seed exchange in highly inbreeding crop species such as barley. In the future, improved mobility of farmers and extension work may facilitate seed exchange over longer distances, and consequently jeopardise preservation of locally adapted landraces in barley.     

涉县旱作梯田系统农业物种及遗传多样性保护与利用

农业生物多样性的研究和保护是全球重要农业文化遗产保护的核心要素。以王金庄为核心的涉县旱作梯田系统2014年被认定为中国重要农业文化遗产,研究其农业生物多样性,可为涉县旱作梯田系统的保护与利用提供依据,为农业文化遗产地农业生物多样性农家就地保护提供参考。本文通过对传统农家品种普查收集与入户访谈、田间调查与种植鉴定,系统研究了涉县旱作梯田系统的农业物种和传统农家品种以及由此形成的保护与利用经验与技术。研究发现涉县旱作梯田系统种植或管理的农业物种26科57属77种,其中粮食作物15种、蔬菜作物31种、油料作物5种、干鲜果14种、药用植物以及纤维烟草等12种。共有包括171个传统农家品种,其中粮食作物62个、蔬菜作物57个、干鲜果品33个、油料作物7个、药用植物和纤维烟草12个。这些农业物种及传统农家品种,通过混合种植、轮作倒茬、间作套种、优中选优等一系列保护与利用技术被活态传承和保护。但随着城镇化和现代农业的快速推进,涉县旱作梯田系统农业生物多样性保护与利用正面临着主体缺失、技术失传、传统农家品种名称混乱、种质退化以及单一化种植造成的品种多样性丧失、单一追求产量造成适应性强的品种资源丧失、农民生计方式多样化造成梯田农业的弱化、传统农家品种生产比较效益低和重要性认识不足等问题,针对这些问题提出了建立动态保护与适应性管理机制、发展特色产业、激发农民内生动力、组织开展资源普查并建立社区种子库与农民自留种相结合的传统农家品种就地活态保护机制等对策与建议。     

硒对苦荞硒、总黄酮和芦丁含量、分布与累积的影响

采用盆栽试验探讨土壤施硒对苦荞硒、总黄酮和芦丁含量、分布与累积的影响。结果看出,在土壤施硒0.5～2.0 mg/kg范围,苦荞根在苗期（40 d）大量吸收并累积硒,全生育期各器官硒含量极显著提高;在生长中后期(60～80 d) 硒的累积最快,累积量最多。硒在苦荞各器官中的分布为:在40 d时,根＞叶＞茎;60 d时Se0.0处理为叶＞根＞花＞茎,施硒各处理则为花＞根＞叶＞茎;80 d时Se0.0处理以花＞根＞叶＞茎＞子粒,Se0.5处理以花＞叶＞子粒＞茎＞根,施硒≥1.0 mg/kg的处理则为花＞叶＞茎＞根＞子粒。土壤施硒≤1.0 mg/kg促进苦荞生长,提高地上部各器官干重和植株总干重以及各器官总黄酮和芦丁含量与累积量,不改变总黄酮和芦丁的器官分布,增加苦荞中后期对总黄酮的累积;以Se0.5处理效应最佳,各差异达显著水平。过量的硒（Se1.5～2.0 mg/kg）显著抑制苦荞生长,降低各器官干重、总黄酮和芦丁含量与累积,不利于硒在子粒中富集和总黄酮在子粒中分布。表明在低硒土壤上栽培苦荞,土壤施硒以不超过1.0 mg/kg为宜,既能最大限度的提高苦荞各器官硒、总黄酮和芦丁含量和累积量,又可降低施用硒肥的成本和减少硒肥对环境的影响。     

Participatory landrace selection for on-farm conservation: An example from the Central Valleys of Oaxaca, Mexico

On-farm conservation is recognized as a key component of a comprehensive strategy to conserve crop genetic resources. A fundamental problem faced by any on-farm conservation project is the identification of crop populations on which efforts should be focused. This paper describes a method to identify a subset of landraces for further conservation efforts from a larger collection representing the diversity found in the Central Valleys of Oaxaca, Mexico. Mexico is a center of origin and diversity for maize (Zea mays L.). The 17 landraces selected from an initial collection of 152 satisfy two criteria. First, they represent the diversity present in the larger collection. Second, they appear to serve the interests of farmers in the region. Data for applying the method were elicited through participatory as well as conventional techniques. They incorporate the complementary perspectives of both men and women members of farm households, and of plant breeders and social scientists.     

Genetic diversity,population structure and differentiation of rice species from Niger and their potential for rice genetic resources conservation and enhancement

Rice genetic resources conservation and evaluation is crucial to ensure germplasm sources for further crop breeding. We conducted a wide collection of Oryza species in Niger and characterize its diversity with microsatellites (or simple sequence repeats, SSR). The aims of this research were to get a better understanding of the extent of genetic diversity, its structure and partition within rice eco-geographical zones of Niger. There were 264 accessions found in farmers’ and other fields: 173 O. sativa (Asia’s rice), 65 O. glaberrima (Africa’s rice), 25 O. barthii, and 1 O. longistaminata (weedy perennial rice), which were genotyped with 18 SSR. A total of 178 alleles were detected, with a mean of 9.89 alleles per locus. The polymorphism information content was 0.65 and heterozygosity was estimated as 0.14. Two main well-differentiate genotypic groups, which correspond to Asian and African rice species, were identified. The SSR set divided the Asia’s rice group (solely indica) into irrigated and floating rice, with rainfed lowland rice in between. The African rice species group was composed of O. glaberrima, O. longistaminata and O. barthii accessions, but without any clear genetic differentiation among them likely due admixtures within the samples of O. barthii. Five accessions that could be natural interspecific hybrids were too admixed for assigning them to any of the two well-differentiated groups. The partitioning of the overall diversity showed that maximum variation was within genotypic groups and subgroups or cropping ecologies, rather than between eco-geographical zones. The eco-geographical distribution of the diversity suggests germplasm exchange in Niger. Next-steps for conserving rice and crop wild relatives in Niger could be taken using the findings of this research.     

Centres of Crop Diversity and/or Origin, Genetically Modified Crops and Implications for Plant Genetic Resources Conservation

The concept of centres of crop diversity and/or origin of agriculture is briefly reviewed. The conservation status of crop genetic resources, either ex situ or in situ, cultivated or wild, has been assessed for species of the Central American and Mexican centre, demonstrating that that region is indeed one of the important centres of crop diversity for human kind. Furthermore, biotechnological developments with regard to the creation and spread of genetically modified crops have been analyzed. The likelihood of unintentional introgression of genetically modified traits into conventional seed lots, crops as well as into germplasm collections have been assessed. Related biosafety measures as well as the possible implications of intellectual property rights on transgenic crops and/or genes are being discussed vis-a-vis the possible implications they might have for germplasm management. The Central American crop genetic resources situation has been used as a “case study” to illustrate the potential impact of the spreading of GM varieties on the genetic diversity in genebanks and farmers’ fields and the need for effective and efficient conservation efforts. Conservation management strategies and practices are being proposed of mitigate the potential negative impact of GM crops on the conservation efforts.     

Maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) management in Yaxcaba,Yucatan, during the twentyfirst century’s first decade is consistent with an overall loss of landrace diversity in southeast Mexico

The status of genetic resource conservation in centers of crop diversity remains disputed. Recent case-study findings of persistent maize diversity in Yaxcaba, Yucatan, a municipality in southeast Mexico, have raised questions on earlier reports of widespread losses across the crop’s center of diversity in Mexico. We break down patterns in maize varietal richness in southeast Mexico to show that temporal trends in Yaxcaba are subsumed under spatial variation in this broader region and consistent with an overall loss of diversity. Persistence of diversity in Yaxcaba can be explained by conditions that allowed subsistence farmers to continue sowing land even as maize prices dropped, but these conditions may be rare in Mexico and likely to change. Yaxcaba emerges as a rare community of exceptional diversity from which valuable policy lessons can be drawn. We find that gaps and omissions in the Mexican Government’s strategy for maize conservation have excluded Yaxcaba and likely resulted in an ineffective intervention elsewhere in the Peninsula. An integrated-systems perspective should help us develop a coherent strategy for resource conservation and climate adaptation based on more efficient and equitable instruments.