Raising the stakes: cassava seed networks at multiple scales in Cambodia and Vietnam
- Published
- Accepted
- Subject Areas
- Agricultural Science, Biogeography, Plant Science
- Keywords
- seed flow, Manihot esculenta, seed systems, vegetatively propagated crops, network analysis
- Copyright
- © 2018 Delaquis et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 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.27124v1
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.
Author Comment
This is a preprint submission to PeerJ Preprints, following submission for peer review at a recognized academic journal.
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.