Landrace cannabis
More actions
Landrace cannabis is a cultivated cannabis population that has evolved over time in a specific geographic region, shaped by local environmental pressures and the selection practices of farmers.[1][2][3] Cannabis landraces are genetically diverse and locally adapted, often valued for distinctive traits such as flavour, resilience or suitability for traditional uses.[1][2]
The defining mechanism of landrace maintenance is mass selection, in which farmers save seed in bulk from open-pollinated populations rather than from individually selected plants.[1][4] This sustains genetic diversity within a recognisable population while applying gradual selection pressure toward locally favoured traits.[1] Landraces are dynamic rather than static and continue to evolve through ongoing seed exchange and occasional introgression.[4]
Cannabis landraces face pressures distinct from most food-crop landraces. Decades of prohibition and eradication have disrupted traditional growing regions, and the rapid global spread of high-yield hybrids has driven extensive genetic displacement.[5][2] The most prominent documented case is the replacement of the Moroccan kif by hybrid varieties such as khardala across the Rif Mountains over the 2000s and 2010s.[5]
Characteristics
Authoritative sources broadly agree on the existence and utility of the landrace classification but differ on the precise criteria. Individual criteria are weighted differently depending on whether the source emphasises governmental regulation, biological science, agribusiness, anthropology, environmental conservation or home cultivation. Not every population agreed to be a landrace exhibits every characteristic.[6]
General features of a landrace may include:
- It is morphologically distinctive yet remains dynamic.[6][7]
- It is genetically adapted to and has a reputation for tolerating local conditions, including climate, disease, pests and prevailing cultural practices.[6][7]
- It is not the product of formal breeding programmes — governmental, organisational or private — and may lack systematic selection, development and improvement by breeders.[2][4][6][8]
- It is maintained less deliberately than a standardised cultivar, with its genetic isolation principally a matter of geography acting upon whatever plants happened to be brought by humans to a given area.[2]
- It has a historical origin in a specific geographic area, will usually have its own local name and is often classified by intended purpose.[6][7][8]
- Where yield can be measured, a landrace shows high stability of yield even under adverse conditions, though only a moderate yield level under carefully managed conditions.[4]
- At the level of genetic testing, its heredity shows a degree of integrity but retains some genetic heterogeneity (i.e. genetic diversity).[6][7][8][9]
Mass selection
A defining mechanism of landrace maintenance is mass selection: farmers save seed from the general population of a crop rather than selecting individual plants for controlled crosses. In each growing cycle, farmers harvest seed from the field as a whole, or from the best-performing portion of it, sow that seed the following season and allow open pollination across the population. This process sustains the genetic diversity within a landrace while applying gradual, directional selection pressure toward locally favoured traits such as vigour, flowering time, resin production or resistance to local pests and diseases.[4][1]
Mass selection is what makes a landrace a population rather than a line. Unlike the pedigree selection and controlled crosses used in formal breeding programmes, mass selection preserves a broad range of genotypes within the population, which in turn provides the raw material for ongoing adaptation to shifting environmental and cultural conditions.[1][4] This genetic breadth is also why individual plants within a landrace may vary considerably in appearance and chemistry while still belonging to a recognisably coherent population.[1]
In cannabis, mass selection has historically taken place alongside practices that exert stronger directional pressure than simple bulk harvest. Roguing of male plants for sinsemilla production removes pollen sources entirely, and selective retention of resin-heavy females for charas or hashish making concentrates the breeding population around individuals favoured for resin yield.[2] In some traditional charas-producing regions, growers reserve seed from plants whose females have been hand-rubbed during the preceding season, applying selection toward resin yield while leaving most population-level diversity intact.citation needed These practices remain distinct from the systematic line-breeding that defines a formal cultivar.[2]
Terminology
The term landrace was coined in the early 20th century to distinguish traditional farmer varieties from modern, uniform cultivars.[3] Early definitions focused on populations that had evolved without formal breeding programmes and were selected primarily by farmers through traditional practices.[1][4] The concept developed against the backdrop of early 20th-century work on the geographic origins of crop diversity, particularly the centres-of-diversity hypothesis articulated by Nikolai Vavilov, who documented the concentration of crop genetic variation in specific source regions and argued for their conservation as the genetic foundation of future agriculture.[10]
Scholars later recognised that landraces are not static or relic-like. They are dynamic populations, constantly evolving through natural selection in local environments, ongoing seed exchange among farmers and occasional introgression from other cultivars or hybrids.[4][1] Zeven (1998) emphasised that landraces continuously contaminate one another through gene flow, leading to gradual adaptation and genetic shifts rather than fixed, pure lines.[4]
An expanded definition
Modern scholarship, notably Casañas et al. (2017), has proposed an expanded definition of the landrace concept. They argue that landraces can legitimately incorporate modern breeding techniques as long as they remain tied to local adaptation, cultural practices and farmer participation:[1]
"Landraces consist of cultivated varieties that have evolved and may continue evolving, using conventional or modern breeding techniques, in traditional or new agricultural environments within a defined ecogeographical area and under the influence of local human culture."[1]
This expanded definition is not universally accepted. Earlier treatments hold that the application of formal breeding methods produces a cultivar derived from a landrace rather than a landrace that happens to use modern methods.[4] The question of where a landrace ends and a cultivar begins remains actively debated in the agronomic literature and has no settled consensus.[4][6]
Autochthonous and allochthonous landraces
A landrace native to, or produced for a long time within, the agricultural system in which it is found is referred to as an autochthonous landrace, while a more recently introduced one is an allochthonous landrace.[4][6][11]
Within academic agronomy, autochthonous landrace is sometimes used with a more technical, productivity-related definition synthesised by Zeven from earlier sources beginning with Mansholt:
"an autochthonous landrace is a variety with a high capacity to tolerate biotic and abiotic stress, resulting in a high yield stability and an intermediate yield level under a low input agricultural system."[4]
When does a landrace stop being a landrace?
If the definition of a landrace is broadly agreed upon, the threshold at which a population ceases to qualify as one is not. Several processes can erode or dissolve landrace status:
- Genetic displacement: introduced hybrids or cultivars cross-pollinate with or outright replace a local population. In Morocco, the traditional cannabis landrace known as kif has been extensively displaced since the early 2000s by hybrid varieties with higher resin yields. As the kif population shrank, farmers began referring to it as beldiya (Arabic for "local"), a generic agricultural term used across crops to distinguish traditional cultivars from foreign introductions (roumiya). Chouvy and Afsahi argue that this lexical shift is itself a marker of displacement: a population only needs to be called "local" once it has ceased to be the norm.[5]
- Formal breeding: when systematic pedigree selection, controlled crosses or backcrossing programmes are applied to a landrace population, the resulting material may retain landrace-derived traits but is more accurately described as a cultivar or breeding line derived from a landrace.[4][1]
- Loss of farmer management: a landrace depends on ongoing human cultivation and mass selection. Feral or ruderal populations descended from former landraces, while potentially valuable genetic resources, are not themselves landraces in the agronomic sense, because the human selection component has been removed.[4][6]
- Bottlenecking through small samples: when a landrace population is reduced to a small number of seeds or plants — whether through ex situ storage, commercial redistribution or collection — genetic drift can rapidly erode the diversity that defines it. The minimum sample size required to adequately represent a cannabis landrace population remains an open question, though it is necessarily larger than the small seed lots typical of commercial distribution.[1][4]
Landraces, cultivars and hybrids
In cannabis nomenclature, these three terms are often confused or used interchangeably, though they describe different genetic categories.
Landraces are populations that have evolved through natural and human selection in specific geographic regions over extended periods, maintaining genetic diversity while exhibiting local adaptation. They represent dynamic gene pools rather than fixed genetic lines.[1][2]
Cultivars (cultivated varieties) are plants intentionally selected and bred for specific, uniform traits through formal breeding programmes. Modern cannabis cultivars are typically stabilised through pedigree selection and controlled crosses to express consistent characteristics across generations.[2]
Hybrids result from intentional crosses between distinct parental lines, whether between different landraces, between cultivars or between landraces and cultivars. First-generation hybrids (F1) often exhibit hybrid vigour but subsequent generations may show significant phenotypic variation as the parental genetics segregate.[2]
A distinction relevant to conservation is between a landrace grown in its region of origin and the same genetic material grown elsewhere. The underlying genotype does not change when seeds are moved, but expression of traits such as resin chemistry, flowering time and morphology can shift substantially under different environmental conditions.[2][12] Such variation is the domain of phenotypic plasticity and terroir rather than a change in genetic identity.[12] A landrace reproduction grown outside its region of origin may be termed an heirloom or preserved line; it retains the genetic profile of the source population but is no longer subject to the local environmental and cultural selection pressures that shaped it.[2][4]
Biodiversity and conservation
A significant proportion of farmers worldwide grow landrace crops.[4] As industrialised agriculture spreads, cultivars selected for high yield, rapid growth, disease and drought resistance and other commercial values have supplanted landraces, putting many at risk of extinction.[4][13]
In 1927, the International Agricultural Congress, organised by the predecessor of the FAO, hosted an extensive discussion on the need to conserve landraces. A recommendation that members organise nation-by-nation landrace conservation did not lead to widespread conservation efforts.[4]
Landraces are often free from intellectual property and other regulatory encumbrances.[14] In some jurisdictions, however, a focus on landrace production may exclude farmers from benefits afforded to producers of genetically uniform organisms (including breeders' rights legislation, easier access to loans and other business services, even the legal right to share seed) where local law favours high-yield agribusiness interests.[14]
Regine Andersen of the Fridtjof Nansen Institute has argued that the erosion of agricultural biodiversity threatens future food security and that the smallholder farmers who are the principal stewards of crop genetic diversity are also among the most economically marginalised.[14] Protecting farmer interests and protecting biodiversity is a central concern of the International Treaty on Plant Genetic Resources for Food and Agriculture (the "Plant Treaty") under the FAO, though its scope is not limited to landraces.[14]
Landraces played a foundational role in the development of standardised breeds but are today threatened by the market success of those same breeds. In developing countries, landraces continue to play an important role, especially in traditional production systems.[13]
Cannabis-specific conservation challenges
Cannabis landraces face a distinct set of pressures that most food-crop landraces do not.[5][2] Decades of prohibition have driven cultivation underground, disrupted intergenerational knowledge transfer and subjected traditional growing regions to repeated eradication campaigns.[2] At the same time, the rapid global spread of high-yield hybrids has introduced genetic contamination into regions where local populations were previously isolated.[5]
The displacement of the kif landrace in Morocco's Rif Mountains is the best-documented example. Chouvy and Afsahi (2014) recorded that hybrid varieties, introduced from Europe beginning in the early 2000s, replaced the traditional kif across the great majority of cultivated area within roughly a decade, driven by three- to fivefold increases in resin yield. The kif variety, adapted to the Rif's dry conditions and capable of rainfed cultivation, gave way to water-intensive hybrids that required deep wells and irrigation infrastructure. The authors documented roughly ten new hybrid varieties displacing kif across the region, with khardala the most widespread by 2013.[5]
In Southeast Asia, traditional cannabis cultivation in Thailand, Cambodia and Laos documented in the mid-twentieth century has been disrupted by sustained eradication campaigns. Martin's 1975 ethnobotanical survey recorded village-scale cultivation of distinct narrow-leaflet drug populations across the region, with detailed local knowledge of seed selection, processing and use; how much of that material survives in situ today is unclear.[15]
In many areas, traditional landraces face similar pressures from imported hybrid genetics. Smallholder farmers continue to maintain seed lines descended from local populations,[2] though commercially produced hybrid seed has become available in some areas and cross-pollination is a recognised concern for the genetic integrity of these populations.citation needed
Cannabis landraces underpinned the development of the commercial cultivars available today, but are now threatened by the market success of those same cultivars. Across South Asia, Southeast Asia, Africa and Latin America, landraces continue to anchor local economies, cultural practices and traditional uses.[13][2]
In situ and ex situ conservation
Three approaches have been used to conserve plant landraces:[1][4]
- In situ: the landrace is grown and conserved by farmers on farms in its region of origin.
- Ex situ (institutional): the landrace is conserved in a gene bank or seed vault, using controls such as laminated packets stored frozen at −18 °C (0 °F).
- Ex situ (informal): the landrace is grown and reproduced in small numbers by enthusiasts, collectors or seed companies, either indoors or outdoors, outside its region of origin.
These approaches are not equivalent. In situ conservation keeps the evolutionary process running: the population continues to adapt to local conditions through ongoing natural selection and mass selection by farmers, and maintains its relationship with the cultural and ecological context that shaped it. Ex situ conservation, whether institutional or informal, preserves a genetic snapshot of the population at the time of collection but removes it from the selection pressures that define a landrace as a living system. Both are necessary: in situ conservation maintains the process; ex situ conservation provides insurance against the loss of the population itself.[1][4][6]
As the area dedicated to landrace cultivation declines, as in the case of wheat landraces in the Fertile Crescent, landraces can become extinct in cultivation. Ex situ practices are therefore essential to avoid losing genetic diversity entirely. Research published in 2020 suggested that existing methods for cataloguing diversity within ex situ gene banks fall short of capturing the appropriate information for landrace crops.[16]
An in situ conservation effort to save the Berrettina di Lungavilla squash landrace made use of participatory plant breeding practices to incorporate the local community into the work.[17]
Documented growing regions on Landrace.Wiki
The following growing regions are documented on the wiki. This listing updates automatically as new region pages are created.
See Growing regions for the full interactive listing with maps and region cards.
See also
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 Casañas, F., Simó, J., Casals, J., & Prohens, J. (2017). "Toward an evolved concept of landrace." Frontiers in Plant Science, 8, 145.
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 Clarke, R. C., & Merlin, M. D. (2013). Cannabis: Evolution and Ethnobotany. University of California Press.
- ↑ 3.0 3.1 von Rümker, K. (1908). "Die systematische Einteilung und Benennung der Getreidesorten für praktische Zwecke." Jahrbuch der Deutschen Landwirtschaftsgesellschaft, 23, 137–167.
- ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 4.21 Zeven, A. C. (1998). "Landraces: A Review of Definitions and Classifications." Euphytica, 104(2), 127–139.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Chouvy, P.-A. & Afsahi, K. (2014). "Hashish revival in Morocco." International Journal of Drug Policy, 25, 416–423.
- ↑ 6.00 6.01 6.02 6.03 6.04 6.05 6.06 6.07 6.08 6.09 Camacho Villa, T. C., Maxted, N., Scholten, M., & Ford-Lloyd, B. (2005). "Defining and Identifying Crop Landraces." Plant Genetic Resources, 3(3), 373–384.
- ↑ 7.0 7.1 7.2 7.3 Harlan, J. R. (1975). Crops and Man. Madison, Wisconsin: American Society of Agronomy and Crop Science Society of America. ISBN 0-89118-032-X.
- ↑ 8.0 8.1 8.2 Friis-Hansen, E. & Sthapit, B., eds. (2000). Participatory Approaches to the Conservation and Use of Plant Genetic Resources. Rome: International Plant Genetic Resources Institute. p. 199. ISBN 978-92-9043-444-3.
- ↑ Harlan, J. R. (1971). "Agricultural Origins: Centers and Noncenters." Science, 174(4008), 468–474.
- ↑ Vavilov, N. I. (1926). "Studies on the Origin of Cultivated Plants." Bulletin of Applied Botany, Genetics and Plant Breeding, 16(2), 1–248.
- ↑ Food and Agriculture Organization of the United Nations (2014). "Section B. Landraces: B.1. Introduction." Resource Book for the Preparation of National Plans for Conservation of Crop Wild Relatives and Landraces.
- ↑ 12.0 12.1 Babaei, S., Mahzooni-Kachapi, S.S., Henareh, M. & Aalami, A. (2024). Morpho-phenological diversity and genotype-by-environment interaction in cannabis (Cannabis sativa L.) landraces. BMC Plant Biology, 24, 151. doi:10.1186/s12870-024-04842-3
- ↑ 13.0 13.1 13.2 Commission on Genetic Resources for Food and Agriculture. "Glossary of Selected Terms." In Vivo Conservation of Animal Genetic Resources. FAO Animal Production and Health Guidelines. UN Food and Agriculture Organization. pp. xv–xx.
- ↑ 14.0 14.1 14.2 14.3 Andersen, R. (2010). "An Issue of Survival." Development & Cooperation. Internationale Weiterbildung und Entwicklung.
- ↑ Martin, M. A. (1975). "Ethnobotanical Aspects of Cannabis in Southeast Asia." In Rubin, V. (ed.), Cannabis and Culture, pp. 63–75. The Hague: Mouton.
- ↑ Ramirez-Villegas, J., Khoury, C. K., Achicanoy, H. A., et al. (2020). "A gap analysis modelling framework to prioritize collecting for ex situ conservation of crop landraces." Diversity and Distributions, 26(6), 730–742.
- ↑ Andreani, L., Camerini, G., Delogu, C., et al. (2022). "How to save a landrace from extinction: the example of a winter squash landrace (Cucurbita maxima Duchesne) in Northern Italy (Lungavilla-Pavia)." Genetic Resources and Crop Evolution, 69(3), 1163–1178.