Raising the stakes: cassava seed networks at multiple scales in Cambodia and Vietnam
Author and article information
Abstract
Cassava is one of the most important annual crops in Southeast Asia, and faces increasing seed borne pest and disease pressures. Despite this, cassava seed systems have received scant research attention. In a first analysis of Vietnamese and Cambodian cassava seed systems, we characterized existing cassava seed systems in 2016-17 through a farmer survey based approach at both national and community scales, with particular focus on identifying seed system actors, planting material management, exchange mechanisms, geographies, and variety use, and performed a network analysis of detected seed movement at the provincial level. Despite their status as self-organized ‘informal’ networks, the cassava seed systems used by farmers in Vietnam and Cambodia are complex, connected over multiple scales, and include links between geographically distant sites. Cassava planting material was exchanged through farmer seed systems, in which re-use of farm-saved supply and community-level exchanges dominated. At the national level, use of self-saved seed occurred in 47 and 64% of seed use cases in Cambodia and Vietnam, respectively. Movement within communes was prevalent, with 82 and 78% of seed provided to others being exchanged between family and acquaintances within the commune in Cambodia and Vietnam, respectively. Yet, meaningful proportions of seed flows, mediated mostly by traders, also formed inter-provincial and international exchange networks, with 20% of Cambodia’s seed acquisitions imported from abroad, especially neighboring Vietnam and Thailand. Dedicated seed traders and local cassava collection points played important roles in the planting material distribution network at particular sites. Sales of planting material were important means of both acquiring and providing seed in both countries, and commercial sale was more prevalent in high-intensity than in low-intensity production sites. Considerable variability existed in local seed networks, depending on the intensity of production and integration with trader networks. Adapted innovations are needed to upgrade cassava seed systems in the face of emerging pests and diseases, taking into account and building on the strengths of the existing systems; including their social nature and ability to quickly and efficiently distribute planting materials at the regional level.
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2018. Raising the stakes: cassava seed networks at multiple scales in Cambodia and Vietnam. PeerJ Preprints 6:e27124v1 https://doi.org/10.7287/peerj.preprints.27124v1Author comment
This is a preprint submission to PeerJ Preprints, following submission for peer review at a recognized academic journal.
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Supplemental Information
Supplementary tables 1-3. General characteristics of cassava-producing households surveyed in Vietnam and Cambodia (2016)
Supplementary table 1. General characteristics of cassava-producing households surveyed in Vietnam and Cambodia (2016). In some cases responses may not equal sample size since participants retained the right to not answer questions, while for others more than one possible answer could be provided simultaneously. Standard deviation (±) reported where applicable.
Supplementary table 2. General characteristics of subnational surveyed households at 2 sites in Cambodia and 2 sites in Vietnam (2016); formatting as in Supplementary table 1.
Supplementary table 3. Household decision makers responsible for decisions relating to seed exchange, identified by survey respondents at 4 sites in Vietnam and Cambodia, expressed in percentage of responses.
Supplementary figure 1. Fruchterman-Reingold plots of respondents’ egocentric stake exchange networks at 4 sites in Cambodia and Vietnam in 2016
Subplots A and B are Cambodian sites, while subplots C and D are Vietnamese sites. Subplot A and C represent low-intensity sites, while B and D are high-intensity sites. Arrows indicate directionality of exchange, while node color denotes type of actor involved in exchange (see legend). Self-loops indicate the use of farm saved seed stocks from the previous year. Note these are visual representations including only exchanges reported by surveyed individuals, not estimates of the full structure of the complete network.
Additional Information
Competing Interests
The authors declare that they have no competing interests.
Author Contributions
Erik Delaquis conceived and designed the experiments, performed the experiments, analyzed the data, contributed reagents/materials/analysis tools, prepared figures and/or tables, authored or reviewed drafts of the paper, approved the final draft.
Kelsey Andersen conceived and designed the experiments, analyzed the data, contributed reagents/materials/analysis tools, prepared figures and/or tables, authored or reviewed drafts of the paper, approved the final draft.
Nami Minato conceived and designed the experiments, performed the experiments, approved the final draft.
Thuy Cu Thi Le performed the experiments, authored or reviewed drafts of the paper, approved the final draft.
Maria E Karssenberg performed the experiments, analyzed the data, prepared figures and/or tables, approved the final draft.
Sophearith Sok performed the experiments, authored or reviewed drafts of the paper, approved the final draft.
Kris AG Wyckhuys conceived and designed the experiments, authored or reviewed drafts of the paper, approved the final draft.
Jonathan C Newby conceived and designed the experiments, authored or reviewed drafts of the paper, approved the final draft.
Dharani Dhar Burra conceived and designed the experiments, performed the experiments, analyzed the data, contributed reagents/materials/analysis tools, approved the final draft.
Srean Pao performed the experiments, authored or reviewed drafts of the paper, approved the final draft, provided local inputs on study site selection and coordinated local survey teams..
Phirun Iv performed the experiments, authored or reviewed drafts of the paper, approved the final draft, provided local inputs on study site selection and coordinated local survey teams..
Niem Le Duc performed the experiments, authored or reviewed drafts of the paper, approved the final draft, provided local inputs on study site selection and coordinated local survey teams..
Nhan Pham Thi performed the experiments, authored or reviewed drafts of the paper, approved the final draft, provided local inputs on study site selection and coordinated local survey teams..
Karen A Garrett conceived and designed the experiments, analyzed the data, contributed reagents/materials/analysis tools, authored or reviewed drafts of the paper, approved the final draft.
Conny JM Almekinders conceived and designed the experiments, authored or reviewed drafts of the paper, approved the final draft.
Paul C Struik conceived and designed the experiments, authored or reviewed drafts of the paper, approved the final draft.
Stef de Haan conceived and designed the experiments, analyzed the data, authored or reviewed drafts of the paper, approved the final draft.
Human Ethics
The following information was supplied relating to ethical approvals (i.e., approving body and any reference numbers):
The methods, data collection, and data handling protocols of this project were reviewed and approved by the International Center for Tropical Agriculture (CIAT) Institutional Review Board, and meet CIAT guidelines for research involving human subjects. Respondents provided oral informed consent prior to survey implementation, and all identifying data were anonymized in the resulting dataset. Participants in the national surveys, from whom plant tissue was also collected for SLCMV diagnostics, also provided written consent.
Data Deposition
The following information was supplied regarding data availability:
The data from this publication is available in the CIAT dataverse online repository at the following address:
https://dataverse.harvard.edu/privateurl.xhtml?token=5b41f90e-8bb7-441b-b776-c6dccae70fca
Funding
This research was undertaken as part of the CGIAR Research Program on Roots, Tubers and Bananas (RTB). Funding support for this work was provided by Australian Centre for International Agricultural Research (ACIAR) (Project number: AGB/2016/032). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
