Potato diversity at height: multiple dimensions of farmer-driven in-situ conservation in the Andes

S. de Haan

    Research output: Thesisexternal PhD, WU

    Abstract

    In-situ conservation
    Two types of in-situ conservation of crop genetic resources can be distinguished: farmer-driven and
    externally driven. The first is subject of this thesis and refers to the persistence of potato genetic resources
    in areas where everyday practices of farmers maintain diversity on-farm. The second concerns the more
    recent phenomenon of Research & Development (R&D) interventions which aim to support in-situ
    conservation by farmers. In this study, farmer-driven in-situ conservation of the potato in the central Andes
    of Peru is investigated at different system levels from alleles, cultivars, and botanical species up to the level
    of the landscape, as well as the interconnected seed and food systems. Dimensions of time and space are
    inferred upon by taking both annual and longer-term spatial patterns into account. Further, diversity is
    linked to selected farmer-based and external drivers.
    Objective and study area
    The overall objective of the study is to enhance our understanding of farmer-driven in-situ conservation
    and the context in which it takes place. The main field research was conducted between 2003 and 2006 in
    eight farmer communities following a north-south transect through the department of Huancavelica.
    Communities were selected on the basis of distribution and distance along the north-south transect,
    tradition of potato cultivation, ethnicity, and relative distance from major markets or cities. Depending on
    the specific dimension of farmer-driven in-situ conservation investigated, a range of different methods
    and tools were used. Chapter 1 provides a brief description of the study area and an overview of the research
    methods used.
    Species, cultivar and allelic diversity
    In chapter 2 the species, morphological and molecular diversity of Andean potatoes in Huancavelica is
    treated at different scales of conservation: farmer family, community, geographically distanced, regional,
    in-situ and ex-situ subpopulations. The infraspecific diversity of in-situ collections was characterized using
    morphological descriptor lists and 18 polymorphic microsatellite markers (SSR). Botanical species were
    determined through ploidy counts in combination with morphological keys. Datasets were used for
    descriptive statistics, (dis)similarity analysis, dendrogram construction, cophenetic analysis, matrix
    correlations calculations (Mantel tests), and Analysis of Molecular Variance (AMOVA).
    Results show that farmers in Huancavelica maintain high levels of species, morphological and molecular
    diversity. All cultivated potato species with the exception of Solanum phureja and Solanum ajanhuiri proved
    to be present. Tetraploid species were most abundant followed by diploids, triploids and pentaploids. A
    total of 557 morphologically unique cultivars were identified based on the morphological characterization
    of 2,481 accessions belonging to 38 in-situ collections. Genetic fingerprinting of 989 accessions belonging
    to 8 in-situ collections resulted in the identification of 406 genetically unique cultivars. AMOVA shows that
    the principal source of molecular variation is found within rather than between geographically distanced
    and farmer family subpopulations. No evidence of genetic erosion was found as the contemporary regional
    in-situ population and a geographically restricted subset of CIP´s ex-situ core collection share 98.8% of
    allelic diversity. Yet, in-situ collections contain numerous unique genotypes.
    Indigenous biosystematics
    The indigenous biosystematics of potatoes (folk taxonomy, folk descriptors and nomenclature) is
    investigated in chapter 3. The chapter includes an extensive literature review on the subject. Folk taxonomy
    was investigated with the use of grouping exercises with farmers, participant observation, and comparison
    of farmer-recognized groups with formal classification based on morphological descriptors and 18
    polymorphic microsatellite markers (SSR). Analysis of the latter was based on (dis)similarity analysis,
    dendrogram construction and consequent levels of coherent clustering by folk taxonomic entity (folk
    specific and varietal taxon). Ethnobotanical free and indicated listing exercises with farmers were used for
    research concerning folk descriptors. Descriptive statistics were used for analysis and interpretation.
    Nomenclature was investigated by applying nomenclature surveys, participant observation and basic
    ethnolinguistic analysis of regional names.
    Folk taxonomy of the potato consists of no less than five ranks. The folk generic rank is composed of
    three taxa: Araq Papa (semi-wild / consumed), Papa Tarpuy (cultivated / consumed), and Atoq Papa (wild /
    not consumed). Folk specific taxa (= cultivar groups) and varietal taxa (= cultivars) within the generic taxon
    of Papa Tarpuy are abundant. Use categories and agroecological criteria are of little importance in the folk
    taxonomical system of the potato. Folk varietal taxa cluster well when using formal morphological
    descriptors; folk specific taxa less so. A moderate concordance, albeit with considerable exceptions, exists
    between folk specific or varietal taxa and their genetic make-up as characterized with molecular markers
    (18 SSR microsatellites). The coherence of clustering in a dissimilarity tree varies for each folk specific or
    varietal taxon considered. Farmers use 22 plant and 15 tuber folk descriptors with recognized character
    states in the Quechua language. Farmers are well able to recognize specific cultivars based on aboveground
    plant parts only (without exposing tubers). Nomenclature is regionally consistent for common cultivars,
    while inconsistent for scarce cultivars. Primary cultivar names (nouns) generally refer to a folk specific taxon
    through predominant metaphorical reference to tuber shape. Secondary cultivar names (adjectives)
    predominantly provide direct reference to tuber color.
    Annual spatial patterns
    Annual spatial management of the potato consists of cropping and labor calendars, field scattering practices,
    and genotype by environmental management. These three dimensions of agrobiodiversity management
    are explored in chapter 4. A structured survey was conducted to investigate the potato cropping and labor
    calendars. Participatory cartography resulted in the detailed mapping of 601 scattered potato fields,
    including their cultivar content, belonging to a total of 122 households. A genotype by environment (GxE)
    experiment employing 4 environments and 31 cultivars was conducted following an altitudinal transect.
    Data obtained was analyzed and interpreted using descriptive statistics, correlation analysis, Geographical
    Information Systems (GIS), Additive main Effects and Multiplicative Interaction (AMMI) analysis, and analysis
    of variance (ANOVA).
    The annual distribution of tasks and labor is primarily an adaptation to the single-season rain-fed
    character and climate extremes of high-altitude agriculture. Three different footplough-based tillage
    systems allow farmers to efficiently manage scarce labor availability for soil preparation. Native-floury, nativebitter
    and improved potato cultivars show considerable overlap concerning their altitudinal distribution
    patterns. The notion that these cultivar categories occupy separate production spaces (so-called “altitudinal
    belts”) is rejected as results show that differences between the altitudinal medians for areal distribution by
    altitude of the different cultivar categories are modest (chapter 4). Field scattering is based on a combined
    logic which results in a patchy distribution of potato genetic diversity across the agricultural landscape.
    Depending on the community, farmers annually crop an average of 3.2 to 9.1 potato fields measuring
    between 660 to 1,576 m² and containing up to a hundred cultivars per field. However, neither field scattering
    nor the management of high levels of diversity by farmers is a direct consequence of niche adaptation as
    most cultivars are versatile (chapter 4). Rather, it is suggested that farmers conduct annual spatial
    management by deploying combined tolerance and resistance traits imbedded in particular cultivar
    combinations in order to confront the predominant biotic and abiotic stresses present in different
    agroecologies. Andean farmers manage GxE adaptation for overall yield stability rather than fine-grained
    environmental adaptation of native cultivars.
    Dimensions of land use
    Three specific dimensions of potato land use were researched in order to gain insights into possible
    contemporary changes affecting the in-situ conservation of potato genetic resources: land use tendencies,
    rotation designs and their intensity, and sectoral fallowing systems (chapter 5). The main research method
    involved participatory cartography using printed poster-size high-resolution Quickbird satellite images
    combined with in-depth consultation through interviews and focus group meetings with members of the
    communities. A total of 4,343 fields and their 1995-2005 crop contents were mapped. The evolution over a
    30-year time-span (1975-2005) of traditional sectoral fallow systems (“diversity hotspots”) was documented
    for each community. Data was analyzed using descriptive statistics and Geographical Information Systems
    (GIS). Processes of change and adaptive innovation were documented by building case studies.
    Land use tendencies between 1995 and 2005 shows that the total cropping area dedicated to improved
    cultivars has grown fast while the area dedicated to native-floury and native-bitter cultivars has remained
    more or less stable. Reduced fallow periods for existing fields and the gradual incorporating of high-altitude
    virgin pasture lands sustain areal growth. Areal growth is particularly fast at extreme altitudes between
    3,900 and 4,350 m. However, fallow periods at these altitudes are still relatively long compared to fields at
    lower altitudes. Results show that fallowing rates increase by altitude for all cultivar categories, but tend to
    be lowest for improved cultivars followed by native-floury and native-bitter cultivars. There is no evidence
    of a straightforward replacement of one cultivar category by another resulting in the replacement and loss
    of infraspecific diversity. Inquiry into the dynamics of sectoral fallow systems over a 30 year period evidences
    the gradual disintegration and abandonment of these systems rich in cultivar diversity. They are replaced
    by more individualist management regimes based on household decision making. Nowadays, the spatial
    patterning of potato genetic diversity within the agricultural landscape is increasingly characterized by
    patchy distribution patterns rather than its concentration within a single communal sector. Where sectoral
    rotation designs survive local innovations have been adopted.
    Farmer seed systems
    Farmer seed systems can be conceived as an overlay of crop genetic diversity determining its temporal
    and spatial patterning. Chapter 6 investigates the relation between selected farmer seed system components
    (storage, health and procurement) and infraspecific diversity of potato in Huancavelica. A sampling exercise
    was carried out in farmer seed stores in order to gain insight into the internal organization of seed stores
    and how this relates to the management of infraspecific diversity. Virus infection rates were determined by
    taking seed tuber samples of diverse cultivars from farmer’s storage facilities. ELISA tests were conduced
    for APMoV, PLRV, PMTV, PVY and PVX. Seed procurement was investigated through a series of structured
    surveys focusing on household seed exchange, the role of regular markets and biodiversity seed fairs, and
    seed provision after severe regional frost. Data was analyzed and interpreted using descriptive statistics.
    Potato seed stores contain different seed lots, reflecting the rationales underlying management of
    cultivar diversity at the field level and the overall structure of infraspecific diversity. Seed health of farmer
    conserved cultivar stocks in Huancavelica is affected by Diabrotica leaf beetle and contact transmitted
    viruses (APMoV, PVX) while aphid and powdery scab transmitted viruses (PMTV, PLRV, PVY) are of limited
    importance. During normal years without extreme events seed exchange of native-floury cultivars is
    practiced by few households and characterized by a limited number of transactions involving small
    quantities of seed of few cultivars covering relatively short distances. Native-bitter and uncommon nativefloury
    cultivars are rarely exchanged and generally reproduced year after year by the same households
    that maintain them. High-altitude diversity-rich communities tend to be net seed exporters. However, the
    capacity of the farmer seed system to annually widely supply and distribute infraspecific diversity is limited.
    Regular markets have a decentralized capacity to supply and widely distribute seed of a limited number of
    well-known cultivars. Frequencies of seed exchange at biodiversity seed fairs are low and involve small
    quantities of a few uncommon cultivars. The resilience of the farmer seed system to cope with severe regional
    seed stress is insufficient for households to be able to restore volumes and cultivar portfolios within a
    short period of time.
    The potato-based food system
    The role of biodiverse potatoes within the human diet in Huancavelica is investigated in chapter 7. Analysis
    to determine the dry matter, gross energy, crude protein, iron (Fe) and zinc (Zn) content of 12 native-floury
    cultivars (fresh / boiled tuber samples) and 9 native-bitter cultivars (boiled unprocessed / boiled processed
    tuber samples) was conduced. Additionally, the nutritional composition of the native-floury cultivars was
    determined after 3 and 5 months of storage under farmer conditions. A food intake study was conducted
    during two contrasting periods of food availability (abundance versus scarcity) in order to quantify and
    characterize the contribution of the potato, different cultivar categories and other food sources to the diet
    of children between 6 and 36 months of age and their mothers. The specific method consisted of direct
    measurement of food intake by weight during a 24 hour period for each household (77 households). Further,
    the overall nutritional status of 340 children aged between 4 and 16 years was determined. Selected cultural
    connotations of the highland diet were investigated through participant and ethnographic observation,
    surveys, and workshops.
    Results show that several native-floury cultivars contain higher contents of specific nutrients (protein,
    iron) than those commonly reported as representative for native potato cultivars. This suggests that
    infraspecific diversity can make a valuable contribution to enhanced nutrition. Storage does not affect the
    nutritional quality of native-floury cultivars very significantly while traditional freeze-drying of native-bitter
    cultivars considerably reduces protein and zinc content. The research shows that malnutrition in
    Huancavelica is primarily a consequence of micronutrient deficiency and secondarily of insufficient total
    energy coverage. The highland diet is heavily dependent on staple foods, particularly potato and barley,
    and generally short in vegetable, fruit, meat and milk intake. The potato contributes significantly to the
    nutritional balance and the recommended requirements for energy, protein, iron and zinc of women and
    children during periods of both food abundance and scarcity. Improved and native-floury cultivars
    complement each other as each category provides the bulk of potatoes consumed at different moments in
    time. The consumption of diverse potato cultivars is entangled with cultural constructions of meals and
    local perceptions of preference traits and quality. The potato itself, as a food item, is no socioeconomic class
    marker. However, certain dishes or products and the overall cultivar diversity grown and used by a household
    shape perceptions of relative wealth.
    Conclusions and implications
    Chapter 8 highlights the main conclusions of the study and provides answers to the original research
    questions while taking the different system levels explored throughout the thesis into account. Selected
    priority areas of future research are identified and, where appropriate, links to other parts of the Andes are
    drawn. Furthermore, the implications for externally driven R&D oriented in-situ conservation efforts seeking
    to support dynamic and ongoing farmer-driven conservation are discussed. It is argued that the science
    and practice of R&D oriented in-situ conservation lag behind the policy commitments to its implementation
    and that institutional learning from diverse projects already implemented throughout the Andes and the
    diffusion of key lessons is essential for the success of future interventions.
    Original languageEnglish
    QualificationDoctor of Philosophy
    Awarding Institution
    • Wageningen University
    Supervisors/Advisors
    • van der Maesen, Jos, Promotor
    • Almekinders, Conny, Co-promotor
    • Bonierbale, M., Co-promotor, External person
    • Thiele, G., Co-promotor, External person
    Award date16 Mar 2009
    Print ISBNs9789085853312
    Publication statusPublished - 16 Mar 2009

    Keywords

    • Solanum
    • potatoes
    • in situ conservation
    • plant genetic resources
    • species
    • cultivars
    • taxonomy
    • diversity
    • andes

    Fingerprint

    Dive into the research topics of 'Potato diversity at height: multiple dimensions of farmer-driven in-situ conservation in the Andes'. Together they form a unique fingerprint.

    Cite this