Edwin Nuijten

Evidence for the Emergence of New Rice Types of Interspecific Hybrid Origin in West African Farmers' Fields

In West Africa two rice species (Oryza glaberrima Steud. and Oryza sativa L.) co-exist. Although originally it was thought that interspecific hybridization is impossible without biotechnological methods, progenies of hybridization appear to occur in farmer fields. AFLP analysis was used to assess genetic diversity in West Africa (including the countries The Gambia, Senegal, Guinea Bissau, Guinea Conakry, Sierra Leone, Ghana and Togo) using 315 rice samples morphologically classified prior to analysis. We show evidence for farmer interspecific hybrids of African and Asian rice, resulting in a group of novel genotypes, and identify possible mechanisms for in-field hybridization. Spontaneous back-crossing events play a crucial role, resulting in different groups of genetic diversity in different regions developed by natural and cultural selection, often under adverse conditions. These new groups of genotypes may have potential relevance for exploitation by plant breeders. Future advances in crop development could be achieved through co-operation between scientists and marginalized farmer groups in order to address challenges of rapid adaptation in a world of increasing socio-political and climatic uncertainty.

Mechanisms Explaining Variety Naming by Farmers and Name Consistency of Rice Varieties in The Gambia

Mechanisms Explaining Variety Naming by Farmers and Name Consistency of Rice Varieties in The Gambia. Understanding variety naming by farmers is important for better understanding crop genetic diversity in farmer fields and its management by farmers. This paper describes variety naming of rice by farmers in The Gambia and presents mechanisms that explain naming diversity and consistency. Three types of variety names can be distinguished, referring to common old varieties, common new varieties, and uncommon varieties. Interview and plant data suggest that variety exchange affects variety naming within villages. As a result, variety names give information on the period of time a variety is used in a village, and on the flow of varieties between and within villages. Name consistency within and between villages results from and illuminates the dynamics of variety exchange within and between villages.

ORGANIZATIONAL ANALYSIS OF THE SEED SECTOR OF RICE IN GUINEA: STAKEHOLDERS, PERCEPTION AND INSTITUTIONAL LINKAGES

SUMMARY This paper analyses the organization of the rice seed sector in Guinea with the overall objectives to assess how organizational settings affect seed supply to small-scale farmers and to suggest institutional changes that would favour seed service and uptake of varieties. Data were collected in Guinea, West Africa, using focus group discussions with extension workers, farmers, representatives of farmers’ associations, agroinput dealers, researchers and non-governmental organization (NGO) staff, and surveys of 91 rice farming households and 41 local seed dealers. Findings suggest that the current institutional settings and perceptions of stakeholders from the formal seed sector inhibit smallholder farmers’ access to seed. Seed interventions in the past two decades have mainly relied on the national extension system, the research institute, NGOs, farmers’ associations and contract seed producers to ensure seed delivery. Although local seed dealers play a central role in providing seed to farmers, governmental organizations operating in a linear model of formal seed sector development have so far ignored their role. We discuss the need to find common ground and alternative models of seed sector development. In particular we suggest the involvement of local seed dealers in seed development activities to better link the formal and the informal seed systems and improve smallholder farmers’ access to seed from the formal sector.

Robustness and Strategies of Adaptation among Farmer Varieties of African Rice (Oryza glaberrima) and Asian Rice (Oryza sativa) across West Africa

This study offers evidence of the robustness of farmer rice varieties (Oryza glaberrima and O. sativa) in West Africa. Our experiments in five West African countries showed that farmer varieties were tolerant of sub-optimal conditions, but employed a range of strategies to cope with stress. Varieties belonging to the species Oryza glaberrima – solely the product of farmer agency – were the most successful in adapting to a range of adverse conditions. Some of the farmer selections from within the indica and japonica subspecies of O. sativa also performed well in a range of conditions, but other farmer selections from within these two subspecies were mainly limited to more specific niches. The results contradict the rather common belief that farmer varieties are only of local value. Farmer varieties should be considered by breeding programmes and used (alongside improved varieties) in dissemination projects for rural food security.

Spatial and temporal dynamics in genetic diversity in upland rice and late millet (Pennisetum glaucum (L.) R. Br.) in The Gambia

Ambiguity exists about the level of genetic diversity represented by farmer crop varieties, how it develops over time and how it relates to the diversity comprised by formal varieties. As part of an interdisciplinary technological/sociological study on farmer management of gene flow, upland rice (Oryza sativa L.) and late millet (Pennisetum glaucum (L.) R.Br.) from The Gambia were investigated for morphological and molecular variation. The goal of these analyses was to obtain insight into the level of crop genetic diversity of farmer’s materials planted in several case study villages in The Gambia. For both crops, samples were collected from villages and various research institutes. Based on variety names, different rice and millet varieties were expected to be used in different villages. In fact, there was a large overlap in genetic diversity for both crops, masked by the use of synonyms. The considerable similarity in rice genetic diversity between villages most likely results from the exchange of varieties between farmers. For millet this seems the result of development of varieties from the same gene pool. Some farmer varieties of rice, however, are apparent hybrid forms between the species O. sativa and O. glaberrima Steud., and farmer varieties in general displayed higher levels of genetic diversity than formal varieties. This indicates that, for rice, genetic diversity develops in farmers’ fields and may have potential use in formal breeding programs.

Processes underpinning development and maintenance of diversity in rice in West Africa: evidence from combining morphological and molecular markers.

We assessed the interplay of artificial and natural selection in rice adaptation in low-input farming systems in West Africa. Using 20 morphological traits and 176 molecular markers, 182 farmer varieties of rice (Oryza spp.) from 6 West African countries were characterized. Principal component analysis showed that the four botanical groups (Oryza sativa ssp. indica, O. sativa ssp. japonica, O. glaberrima, and interspecific farmer hybrids) exhibited different patterns of morphological diversity. Regarding O. glaberrima, morphological and molecular data were in greater conformity than for the other botanical groups. A clear difference in morphological features was observed between O. glaberrima rices from the Togo hills and those from the Upper Guinea Coast, and among O. glaberrima rices from the Upper Guinea Coast. For the other three groups such clear patterns were not observed. We argue that this is because genetic diversity is shaped by different environmental and socio-cultural selection pressures. For O. glaberrima, recent socio-cultural selection pressures seemed to restrict genetic diversity while this was not observed for the other botanical groups. We also show that O. glaberrima still plays an important role in the selection practices of farmers and resulting variety development pathways. This is particularly apparent in the case of interspecific farmer hybrids where a relationship was found between pericarp colour, panicle attitude and genetic diversity. Farmer varieties are the product of long and complex trajectories of selection governed by local human agency. In effect, rice varieties have emerged that are adapted to West African farming conditions through genotype × environment × society interactions. The diversity farmers maintain in their rice varieties is understood to be part of a risk-spreading strategy that also facilitates successful and often serendipitous variety innovations. We advocate, therefore, that farmers and farmer varieties should be more effectively involved in crop development.

Pollen flows within and between rice and millet fields in relation to farmer variety development in the Gambia

In areas with less favourable conditions for agriculture, informal seed systems permit gene flow through pollen to play a crucial role in the development of new varieties. An important factor with great impact on cross-pollination is the plant breeding system, but so far this is little studied within the context of low-input farming systems. This research studied the chances of cross-pollination within and between rice fields in The Gambia. Size and time of flowering were measured for 28 rice fields in one village. The level of mixture was measured in 90 seed lots of rice collected from four villages. Based on the results, we suggest that in general cross-pollination between different rice genotypes occurs more often within fields than between fields. No clear relationship was found between the level of within-field mixture and socio-economic status of farmers. Some comparison was made with millet, which allowed the identification of various factors influencing pollen flow between different genotypes. Effective pollen flow (between genotypes) is a function of a number of factors, such as the rate of cross-pollination of a crop, number of off-types within fields, variety distinctiveness, farmer expert knowledge, length and reliability of the rainy season, growth duration of different varieties, availability of fields, pest pressure and number of varieties grown per field or per farmer. We hypothesize that a low cross-pollination rate is more favourable for the development of new varieties in farmer fields than a high cross-pollination rate.

Towards resilience through systems-based plant breeding. A review

How the growing world population can feed itself is a crucial, multi-dimensional problem that goes beyond sustainable development. Crop production will be affected by many changes in its climatic, agronomic, economic, and societal contexts. Therefore, breeders are challenged to produce cultivars that strengthen both ecological and societal resilience by striving for six international sustainability targets: food security, safety and quality; food and seed sovereignty; social justice; agrobiodiversity; ecosystem services; and climate robustness. Against this background, we review the state of the art in plant breeding by distinguishing four paradigmatic orientations that currently co-exist: community-based breeding, ecosystem-based breeding, trait-based breeding, and corporate-based breeding, analyzing differences among these orientations. Our main findings are: (1) all four orientations have significant value but none alone will achieve all six sustainability targets; (2) therefore, an overarching approach is needed: “systems-based breeding,” an orientation with the potential to synergize the strengths of the ways of thinking in the current paradigmatic orientations; (3) achieving that requires specific knowledge development and integration, a multitude of suitable breeding strategies and tools, and entrepreneurship, but also a change in attitude based on corporate responsibility, circular economy and true-cost accounting, and fair and green policies. We conclude that systems-based breeding can create strong interactions between all system components. While seeds are part of the common good and the basis of agrobiodiversity, a diversity in breeding approaches, based on different entrepreneurial approaches, can also be considered part of the required agrobiodiversity. To enable systems-based breeding to play a major role in creating sustainable agriculture, a shared sense of urgency is needed to realize the required changes in breeding approaches, institutions, regulations and protocols. Based on this concept of systems-based breeding, there are opportunities for breeders to play an active role in the development of an ecologically and societally resilient, sustainable agriculture.