Conservation Of Crop Genetic Diversity Research Articles

Exploring the emergence of participatory plant breeding in countries of the Global North – a review

AbstractParticipatory plant breeding (PPB), commonly applied in the Global South to address the needs of underserved farmers, refers to the active collaboration between researchers, farmers and other actors throughout the breeding process. In spite of significant public and private investments in crop variety improvement in the Global North, PPB is increasingly utilized as an approach to address cropping system needs. The current study conducted a state-of-the-art review, including a comprehensive inventory of projects and five case studies, to explore the emergence of PPB in the Global North and inform future PPB efforts. Case studies included maize (Zea mays), tomato (Solanum lycopersicum), Brassica crops (Brassica oleracea), wheat (Triticum aestivum) and potato (Solanum tuberosum). The review identified 47 projects across the United States, Canada and Europe including 22 crop species representing diverse crop biology. Improved adaptation to organic farming systems and addressing principles and values of organic agriculture emerged as consistent themes. While projects presented evidence that PPB has expanded crop diversity and farmer's access to improved varieties, obstacles to PPB also emerged including challenges in sustained funding as well as addressing regulatory barriers to the commercial distribution of PPB varieties. Agronomic improvements were only one lens motivating PPB, with many projects identifying goals of conservation of crop genetic diversity, farmers' seed sovereignty and avoidance of certain breeding techniques. The authors conclude that a multidisciplinary approach is needed to fully understand the social, political and agroecological influences driving the emergence of projects in the Global North and factors impacting success.

Genetic diversity and structure of the critically endangered Artocarpus annulatus, a crop wild relative of jackfruit (A. heterophyllus).

Limestone karsts of Southeast Asia can harbor high levels of endemism, but are highly fragmented, increasingly threatened, and their biodiversity is often poorly studied. This is true of the Padawan Limestone Area of Sarawak, Malaysia, home to the endemic Artocarpus annulatus, the closest known wild relative of two important and underutilized fruit tree crops, jackfruit (A. heterophyllus) and cempedak (A. integer). Identifying and conserving crop wild relatives is critical for the conservation of crop genetic diversity and breeding. In 2016 and 2017, five A. annulatus populations were located, and leaf material, locality information, and demographic data were collected. Microsatellite markers were used to assess genetic diversity and structure among populations, and to compare levels of genetic diversity to closely related congeneric species. Results indicate no evidence of inbreeding in A. annulatus, and there is no genetic structure among the five populations. However, diversity measures trended lower in seedlings compared to mature trees, suggesting allelic diversity may be under threat in the youngest generation of plants. Also, genetic diversity is lower in A. annulatus compared to closely related congeners. The present study provides a baseline estimate of A. annulatus genetic diversity that can be used for comparison in future studies and to other species in the unique limestone karst ecosystems. Considerations for in situ and ex situ conservation approaches are discussed.

Diminishing Farm Diversity of East African Highland Bananas in Banana Bunchy Top Disease Outbreak Areas of Burundi—The Effect of Both Disease and Control Approaches

Disease-driven selection favours evasive, tolerant, and resistant cultivars, changing cultivar diversity significantly. Since its outbreak in Burundi in the late 1980s, Banana Bunchy Top Disease (BBTD) has now spread to 5 out of 18 provinces across the country, principally through informal seed exchanges. Control approaches have focused on using tissue culture clean planting material and eradicating infected mats. This study investigated the impact of BBTD and its control measures on seed selection practices and banana cultivars diversity in Burundi, by comparing two BBTD endemic sites and one where the disease wasn’t reported. Results have shown that in addition to agronomic traits used in all sites, some BBTD-typical symptoms were used in seed selection in the endemic areas. Own seed provisioning and formal seed sources networks were more likely to be observed in BBTD-endemic areas, compared with the non-endemic area. Disease control using certified tissue culture planting materials reduced the varietal diversity of local cultivars but enabled the introduction of new cultivars. A general reduction in the diversity of local cultivars grown by farmers in the BBTD endemic zones was observed, with about half of the diversity per farmer compared to the non-endemic zone. Farmer demand for varieties (local and improved) was not different between the two areas. Sustainable conservation of crop genetic diversity in the presence of disease invasions remains a problem to be addressed. Thus, implementing seed system-linked intervention with an explicit and monitored diversity conservation objective would increase the sustainability of agricultural production in such situations.

Inter- and Intraspecific Edible Plant Diversity of the Tének Milpa Fields in Mexico

Traditional land use systems are often rich in crop diversity. However, complete inter- and intraspecific data are scarce, limiting our understanding and underestimating the diversity of plant genetic reservoirs. This study attempted to characterize the total edible plant diversity of the milpas, or polyculture maize-based fields, managed by Tenek communities in Mexico. In 41 milpas belonging to 33 farmers in three localities at different altitudes, 191 edible plant types were inventoried, comprising 84 species that include 140 variants and 51 species with no variants. Diversity varies between and within localities. Only 8.4% of the diversity is shared among the localities and, on average, 61.2% of the total richness is managed by single farmers. The intermediate altitude has higher diversity, including 67.5% of the total richness. Crop population numbers are low and highly variable. To contribute to the interpretation and application of results, a proposed method to identify priority crops, sites, and farmers is presented. This study shows, once again, that indigenous farming communities are key actors for the use and conservation of crop genetic diversity. More detailed studies such as this may evidence much larger managed crop diversity than currently is acknowledged.

An Analysis of Social Seed Network and Its Contribution to On-Farm Conservation of Crop Genetic Diversity in Nepal

Social seed systems are important for the maintenance of crop genetic diversity on farm. This is governed by local and informal system in the community through a farmers’ network. This paper analyses these local seed systems through application of social network analysis tools and mappings and examines the network member and its stability over space and time in a small rice farming community in Nepal. NetDraw software is used for data analysis and network mapping. We found that the dynamic network structure had key role in provisioning of traditional varieties and maintaining of crop genetic diversity on farm. We identify and ascertain the key network members, constituted either as nodal or bridging (connector) farmers, occupying central position in the network who promote seed flow of local crop diversity, thus strengthening crop genetic resource diversity on farm.

Conservation of Crop Genetic Diversity for Sustainable Agriculture

Crop genetic diversity is crucial for the environment, for feeding humanity and for sustainable agriculture development, which is providing genetic barriers against different biotic and abiotic stresses; however, it is being lost at an alarming rate. Fortunately, more and more people are conscious of the conservation and sustainable use of genetic resources goes far beyond avoiding the extinction of species, and the objective must be to conserve and use as much diversity as possible within each species. There is now a need for an integrated strategy for the conservation and management of crop genetic diversity and the organization of related information at several levels, for instance, at the highest level, it is necessary for entire agro-ecosystem, and also applies to the gene pools of individual crops at the interspecies level as well as at the intervarietal levels. This paper assesses the estimates methods on different genetic diversity in crop, introduces the status of crop genetic diversity, and prospects the significant conservation of crop genetic diversity for sustainable agriculture in the future.

Evolutionary response of landraces to climate change in centers of crop diversity.

Landraces cultivated in centers of crop diversity result from past and contemporary patterns of natural and farmer-mediated evolutionary forces. Successful in situ conservation of crop genetic resources depends on continuity of these evolutionary processes. Climate change is projected to affect agricultural production, yet analyses of impacts on in situ conservation of crop genetic diversity and farmers who conserve it have been absent. How will crop landraces respond to alterations in climate? We review the roles that phenotypic plasticity, evolution, and gene flow might play in sustaining production, although we might expect erosion of genetic diversity if landrace populations or entire races lose productivity. For example, highland maize landraces in southern Mexico do not express the plasticity necessary to sustain productivity under climate change, but may evolve in response to altered conditions. The outcome for any given crop in a given region will depend on the distribution of genetic variation that affects fitness and patterns of climate change. Understanding patterns of neutral and adaptive diversity from the population to the landscape scale is essential to clarify how landraces conserved in situ will continue to evolve and how to minimize genetic erosion of this essential natural resource.

From the kitchen and the field: Gender and maize diversity in the Bajío region of Mexico

The conservation of crop genetic diversity in farmers’ fields is important for future food security. Recent research on women and biodiversity has emphasized the importance of women’s knowledge in plant domestication and biodiversity conservation. This paper presents a case study of the differences in women’s and men’s knowledge of maize landraces in four different environments in the Bajío region of Mexico. We argue that research on crop diversity and conservation needs to include both men and women farmers’ knowledge. Gendered knowledge results from men and women in a household being responsible for different tasks and sometimes for farming separate plots. In addition, as economic pressures increasingly force men to work away from their communities for extended periods, women become the primary agricultural decision‐makers.

Market-based incentives for conserving diversity on farms: the case of rice landraces in Central Tarai, Nepal

Market-based incentives are one means of encouraging farmers to grow landraces that are also of social value, thereby contributing to the conservation of crop genetic diversity on farms – and in principle, the cheapest. This study uses a participatory, market systems approach supplemented by baseline data from an ongoing project to analyze markets for rice landraces and modern varieties in Nepal. Nepal is located in the area of origin and diversity for Asian rice. With the exception of traditional Basmati rice (which is of high aromatic quality), most rice landraces are traded through small-scale informal channels. Traders earn higher profits handling modern varieties than landraces, with the exception of Basmati, which competes with modern varieties. The superior consumption qualities of Basmati are valued in markets, but conserving these landraces may not have great social value. Furthermore, farmers who grow Basmati are clearly better off than those who do not. Findings raise questions about the role of market-based incentives for conserving landraces on farms, the costs entailed in establishing a structure to generate them, and about efficiency vs. equity considerations in the design of conservation programs.

The current status and perspectives of on farm conservation of crop genetic diversity

Effective conservation of traditional crop varieties is the basis of the long term utilization of agricultural biodiversity, and will be one of the essential factors for the sustainable development of agriculture. Due to the intensive production practices in modern agriculture, a great number of traditional crop varieties have been rapidly replaced by the improved high yielding varieties, which has caused severe "genetic erosion" in the genepool of crop species, and significantly reduced genetic diversity of crop varieties. It is therefore essential to preserve the shrinking crop biodiversity before it is completely lost. On farm conservation is an important and dynamic in situ conservation method that conserves crop varieties in agricultural ecosystems. On farm conservation can be defined as the continued cultivation and management of a diverse set of crop populations by farmers in the agro ecosystems where a crop has evolved, and it allows the evolution of conserved crop varieties to be continued in their original habitats. However, in spite of the increasing interests in this method and a relatively large number of research and case studies reported in this field, there has been no significant achievement for on farm conservation and many questions remain unanswered: Is on farm conservation practical and achievable? Can on farm conservation actually be conducted in modern agriculture? Is on farm conservation a trade off with agricultural development? What are the scientific issues for on farm conservation? What incentives can their be for farmers to conserve genetic diversity in their farming ecosystems? All these questions need to be addressed scientifically with satisfaction when conducting effective on farm conservation. It is therefore necessary to have a better understanding of on farm conservation, to study mechanisms and scientific basis of on farm conservation, and to be innovative to open a new dimension for on farm conservation action. The biodiverse deployment of rice varieties, mixed planting of modern hybrid rice with traditional rice varieties in Yunnan Province, not only provided an excellent method of controlling rice disease and increasing rice productivity, but also demonstrated a powerful model for conserving traditional rice varieties in an effective and sustainable way. This model of mixed planting of a diverse set of crop varieties links farmer's long term benefit, socioeconomic concerns, and the actual conditions of locally based agro ecosystems appropriately with conservation activities. This model of using biodiversity to preserve biodiversity of crop varieties is a long term approach that will be sustainable and beneficial to farmers whose general living standard will be raised. It might provide possible solution for on farm conservation of traditional rice varieties in a feasible and sustainable way., and probably has potential for other crop species, too.

Biodiversity and modern crop varieties: Sharpening the debate

Debates about the relationship between agricultural technology and the conservation of crop genetic diversity are often hampered by unclear vocabulary and imprecise data. Various interpretations of the terms “modern variety,” “local variety,” “hybrid,” and “green revolution” are first explored, and then evidence is examined regarding the effect of modern varieties on intra- and intercrop diversity, risk, input use, and farmer decision-making. The objective is to urge a more reasoned debate about the future of plant genetic resources.