The tricot approach: an agile framework for decentralized on-farm testing supported by citizen science. A retrospective.

Matching crop varieties to their target use context and user preferences is a challenge faced by many plant breeding programs serving smallholder agriculture. Numerous participatory approaches proposed by CGIAR and other research teams over the last four decades have attempted to capture farmers' priorities/preferences and crop variety field performance in representative growing environments through experimental trials with higher external validity. Yet none have overcome the challenges of scalability, data validity and reliability, and difficulties in capturing socio-economic and environmental heterogeneity. Building on the strengths of these attempts, we developed a new data-generation approach, called triadic comparison of technology options (tricot). Tricot is a decentralized experimental approach supported by crowdsourced citizen science. In this article, we review the development, validation, and evolution of the tricot approach, through our own research results and reviewing the literature in which tricot approaches have been successfully applied. The first results indicated that tricot-aggregated farmer-led assessments contained information with adequate validity and that reliability could be achieved with a large sample. Costs were lower than current participatory approaches. Scaling the tricot approach into a large on-farm testing network successfully registered specific climatic effects of crop variety performance in representative growing environments. Tricot's recent application in plant breeding networks in relation to decision-making has (i) advanced plant breeding lines recognizing socio-economic heterogeneity, and (ii) identified consumers' preferences and market demands, generating alternative breeding design priorities. We review lessons learned from tricot applications that have enabled a large scaling effort, which should lead to stronger decision-making in crop improvement and increased use of improved varieties in smallholder agriculture.

Forgotten food crops in sub-Saharan Africa for healthy diets in a changing climate.

As climate changes in sub-Saharan Africa (SSA), Africa's "forgotten" food crops offer a wide range of options to diversify major staple production as a key measure toward achieving zero hunger and healthy diets. So far, however, these forgotten food crops have been neglected in SSA's climate-change adaptation strategies. Here, we quantified their capacity to adapt cropping systems of SSA's major staples of maize, rice, cassava, and yams to changing climates for the four subregions of West, Central, East, and Southern Africa. We used climate-niche modeling to explore their potential for crop diversification or the replacement of these major staples by 2070, and assessed the possible effects on micronutrient supply. Our results indicated that approximately 10% of the present production locations of these four major staples in SSA may experience novel climate conditions in 2070, ranging from a high of almost 18% in West Africa to a low of less than 1% in Southern Africa. From an initial candidate panel of 138 African forgotten food crops embracing leafy vegetables, other vegetables, fruits, cereals, pulses, seeds and nuts, and roots and tubers, we selected those that contributed most to covering projected future and contemporary climate conditions of the major staples' production locations. A prioritized shortlist of 58 forgotten food crops, able to complement each other in micronutrient provision, was determined, which covered over 95% of assessed production locations. The integration of these prioritized forgotten food crops in SSA's cropping systems will support the "double-win" of more climate-resilient and nutrient-sensitive food production in the region.

Use Patterns, Knowledge Diversity and Drivers for the Cultivation of the Miracle Plant [Synsepalum dulcificum (Schumach & Thonn.) Daniell] in Benin and Ghana.

Despite the growing interest in the miracle plant worldwide due to its numerous applications, the threats and the wild harvest of the species hamper its sustainable utilisation. Moreover, traditional knowledge so far documented on the species is limited to a narrow geographical coverage of its natural distribution range, which is West and Central Africa. This study analysed the use variation and knowledge acquisition pattern of the miracle plant among West African sociolinguistic groups and deciphered the drivers of populations' willingness and readiness to engage in cultivating the species. Semi-structured interviews were conducted with 510 respondents purposively selected from nine sociolinguistic groups in Benin and Ghana using the snowball sampling approach. Information was collected on respondents' socio-demographic profile, miracle plant ownership, plant parts used and preparation methods, knowledge of the species bioecology, perceived threats on the species, willingness to cultivate, maximum acreage to allocate to the species and maximum price to pay for a seedling. Descriptive statistics, generalized linear models, classification and regression tree models were used for data analysis. The miracle plant ownership mode depended on the age category. Sociolinguistic affiliation, level of schooling, migratory status and religion significantly affected the number of trees owned. We recorded 76 uses belonging to six use categories. The overall use-value of the miracle plant significantly varied according to the respondent sociolinguistic affiliation, main activity and religion. Men were the main source of knowledge and knowledge is mainly acquired along the family line. Knowledge related to food and social uses was mostly acquired from parents and people of the same generation, while magico-therapeutic and medicinal use-related knowledge were inherited from parents and grandparents. Sociolinguistic affiliation, awareness of taboos and market availability were the most important drivers of respondent willingness to cultivate the miracle plant. While the respondent's level of schooling and perception of plant growth rate determined the maximum acreage they were willing to allocate to the species in cultivation schemes, their main activity, sociolinguistic affiliation and knowledge of the species time to fruiting drove the maximum purchase price they were willing to offer for a seedling of the species. Our findings provide key information for the promotion of miracle plant cultivation in the study area.

Comparative analysis of management practices and end-users' desired breeding traits in the miracle plant [Synsepalum dulcificum (Schumach & Thonn.) Daniell] across ecological zones and sociolinguistic groups in West Africa.

BACKGROUND: Understanding end-users' preferred breeding traits and plant management practices is fundamental in defining sound breeding objectives and implementing a successful plant improvement programme. Since such knowledge is lacking for Synsepalum dulcificum, a worldwide promising orphan fruit tree species, we assessed the interrelationships among socio-demography, ecology, management practices, diversity and ranking of desired breeding traits by end-users of the species (farmers, final consumers and processing companies) in West Africa. METHODS: Semi-structured interviews, field-visits and focus groups were combined to interview a total of 300 farmers and final consumers belonging to six sociolinguistic groups sampled from three ecological zones of Benin and Ghana. One processing company in Ghana was also involved. Data collected included socio-demographic characteristics; crop management systems and practices; and preferences of farmers, final consumers and processing companies and ranking of breeding traits. Data were analysed using descriptive statistics, independence, and non-parametric tests, generalized linear models, multi-group similarity index and Kendall's concordance coefficient. RESULTS: Men (86.33% of respondents) were the main holders of S. dulcificum in the study area. The three most frequent management practices observed in the species included weeding, fertilization and pruning, which were applied by 75.66%, 27.33% and 16.66% of respondents, respectively. The management intensity index varied significantly across ecological zones, sociolinguistic groups, and instruction level (p < 0.001) but was not affected by gender (p > 0.05). General multigroup similarity indices ([Formula: see text]) for farmer-desired traits, on one hand, and final consumer-desired traits, on the other hand, were high across ecological zones ([Formula: see text] ≥ 0.84) and sociolinguistic groups ([Formula: see text] > 0.83). Nevertheless, respondents from the Guineo-Congolian (Benin) and the Deciduous forest (Ghana) zones expressed higher agreement in the ranking of desired breeding traits. Preference for breeding traits was 60% similar among farmers, final consumers, and processors. The key breeding traits desired by these end-users included in descending order of importance big fruit size, early fruiting, high fruit yielding (for farmers); big fruit size, high fruit miraculin content, fruit freshness (for final consumers); and high fruit miraculin content, big fruit size, high fruit edible ratio (for processing companies). CONCLUSION: This study revealed stronger variations in current management practices across ecological zones than across sociolinguistic groups. A high similarity was shown in end-users' preferences for breeding traits across the study area. Top key traits to consider in breeding varieties of S. dulcificum to meet various end-users' expectations in West Africa include fruit size and fruit miraculin content. These results constitute a strong signal for a region-wide promotion of the resource.

Phenotypic variation, functional traits repeatability and core collection inference in Synsepalum dulcificum (Schumach & Thonn.) Daniell reveals the Dahomey Gap as a centre of diversity.

The miracle plant Synsepalum dulcificum is a multipurpose natural sweetener and a promising West African orphan fruit shrub candidate for genetic improvement. Unfortunately, basic knowledge such as phenotypic variation and inheritance estimates required for implementing a breeding program are still lacking. A set of 203 accessions were sampled in two habitats from seven populations spread across the Dahomey Gap (DG) and the Upper Guinea forest (UG) in West Africa. The phenotypic diversity and allometric relationships among functional traits were analysed; the broad-sense heritability was estimated for fruit-traits, and a mini-core collection was developed in the species. Quantitative variation in tree- and fruit-traits was recorded, and multivariate analyses were performed to assess relationships among accessions, whereas heritability was estimated using the coefficient of repeatability. Tree-traits observed in S. dulcificum were more variable than fruit-traits. While habitat-type only affected tree-traits, the provenance population significantly affected both fruit- and tree-traits, with the UG populations outperforming the DG ones. Significant correlations were observed among fruit-traits on one hand, and among tree-traits on the other hand, whereas poor correlations were observed between tree- and fruit-traits. The multivariate analysis grouped accessions in three clusters. Promising individuals for high fruit mass and pulp-dense genotypes' selection were identified within clusters. Repeatability estimates for fruit-traits ranged from 0.015 (edible ratio) to 0.88 (fruit mass). The Core Hunter algorithm enabled the extraction of 41 individuals as robust representatives of the initial set of 203 accessions, and the mapping of this core collection suggested Dahomey Gap as a centre of diversity of the species. These original findings offer opportunities, not only for the genetic improvement of S. dulcificum, but also for targeted ex-situ conservation in the species.

Initial Plant Vigor and Short Rotation Coppices Improve Vegetable Production in Vitex doniana Sweet (Lamiaceae).

Vitex doniana is a major but threatened economic plant collected as a leafy vegetable and fruit in West Africa. How the species withstands coppicing as an agricultural management practice was investigated in this research. Three seedling vigor classes (10-25 mm, 25-30 mm, 30-40 mm) and two coppicing heights (20 and 40 cm) were compared to controls in eight replicates using a randomized complete block design. Mixed effect models were used to compare the effects of treatments on sprouting intensity, sprout growth, and biomass yield in the short (12 months) and medium term (three and five years). Results indicated that V. doniana is a fast-growing species, with heights between 2.72-7.73 m and diameter at breast height between 4.46-14.64 cm in five years. Vigorous (basal diameter > 30 mm) and shorter coppices (20 cm high) produced a higher number of sprouts. Although biomass yield was relatively higher on high coppices, the difference was not statistically significant. While a more severe harvesting regime was detrimental to plant growth, V. doniana can be managed to produce both vegetables and fuel wood in the medium term. These findings are significant for further improvement of the species, for food security, and climate resilience.

A combination of approaches evidenced seed storage behaviour in the miracle berry Synsepalum dulcificum (Schumach. et Thonn.) Daniell.

BACKGROUND: Knowledge on seed storage behaviour is crucial for planning conservation strategies of plant genetic resources particularly in economically promising but endangered species like Synsepalum dulcificum, viewed as recalcitrant-seeded species albeit sound evidence was lacking. In this study, we combined an experimental approach based on critical moisture content and storage environment analysis, and the seed-coat ratio-seed dry mass (SCR-SM) model to clarify the seed storage behaviour in the species. Seed moisture content at shedding was determined and effects of dehydration and cold storage on seed viability, germination and subsequent seedling vigour were analysed. The probability for dessication-senstivity [P(D-S)] was also determined. RESULTS: Our findings indicated that S. dulcificum seed moisture content at shedding was 36.60% with nearly 100% viability. Seed dehydration below 20% moisture content induced a total loss of viability whereas low temperature storage (at 10 °C or 4 °C reduced shelf life to a maximum of 7 days. More importantly, S. dulcificum seed storage at 0 °C was highly detrimental and resulted in a total loss of viability whatever the storage duration. Only a storage at 25 °C helped expand the shelf life to 28 days. However, at 28 days storage the viability was extremely low with almost no germination. The probability for dessication-senstivity P(D-S) in the species is largely greater than 0.5. Seed dehydration and storage environment highly affected subsequent germination rate and seedling vigour. While dehydration improved seedling performance storage at low temperature rather inhibited seedling growth. CONCLUSION: Taken together, these findings are the first to set evidence of recalcitrance in S. dulcificum and serve hands-on information for practical handling of the seeds and designing sustainable conservation practices for adequate future breeding programme in the species.

Shade and nutrient-mediated phenotypic plasticity in the miracle plant Synsepalum dulcificum (Schumach. & Thonn.) Daniell.

Phenotypic plasticity as a change of genotype expression in response to environmental heterogeneity varies in magnitude among crop species and can induce a shift in a plant's phenology. In Synsepalum dulcificum, a West African orphan fruit tree, such phenological plasticity is not well understood. Here, we hypothesize that light stimulation and changes in organic nutrient availability would induce an accelerated transition in S. dulcificum from its juvenile to its reproductive phase. We grew 14-month-old seedlings of S. dulcificum under a range of nutrient regimes, both in shade and in full sunlight, and measured their survival, vegetative growth, biomass allocation, and transition to reproductive maturity. The results reveal that S. dulcificum responds favourably to both shading and nutrient application, with the shading exhibiting a stronger influence on the measured variables. The species' morphological plasticity, particularly in terms of plant height and stem diameter, was found to exceed both its fitness and allocational plasticities. Under the conditions examined, we observed an accelerated transition to fruiting, at an age of only 24 months. The observed plasticity suggests S. dulcificum to be an intermediate shade-tolerant species. This finding expands our knowledge on the appropriate environmental conditions for the breeding and cultivation of this species.

Early fruiting in Synsepalum dulcificum (Schumach. & Thonn.) Daniell juveniles induced by water and inorganic nutrient management.

Background. The miracle plant, Synsepalum dulcificum (Schumach. & Thonn.) Daniell is a native African orphan crop species that has recently received increased attention due to its promise as a sweetener and source of antioxidants in both the food and pharmaceutical industries. However, a major obstacle to the species' widespread utilization is its relatively slow growth rate and prolonged juvenile period. Method. In this study, we tested twelve treatments made up of various watering regimes and exogenous nutrient application (nitrogen, phosphorus and potassium, at varying dosages) on the relative survival, growth, and reproductive development of 15-months-old S. dulcificum juveniles. Results. While the plants survived under most tested growing conditions, nitrogen application at doses higher than 1.5 g [seedling] -1 was found to be highly detrimental, reducing survival to 0%. The treatment was found to affect all growth traits, and juveniles that received a combination of nitrogen, phosphorus, and potassium (each at a rate of 1.5 g [seedling] -1), in addition to daily watering, exhibited the most vegetative growth. The simple daily provision of adequate water was found to greatly accelerate the transition to reproductive maturity in the species (from >36 months to an average of 23 months), whereas nutrient application affected the length of the reproductive phase within a season, as well as the fruiting intensity. Conclusions. This study highlights the beneficial effect of water supply and fertilization on both vegetative and reproductive growth in S. dulcificum. Water supply appeared to be the most important factor unlocking flowering in the species, while the combination of nitrogen, phosphorus and potassium at the dose of 1.5 g (for all) consistently exhibited the highest performance for all growth and yield traits. These findings will help intensify S. dulcificum's breeding and horticultural development.

Modelling socioeconomic determinants for cultivation and in-situ conservation of Vitex doniana Sweet (Black plum), a wild harvested economic plant in Benin.

BACKGROUND: Cultivation is the most appropriate management option when both demand and harvesting of wild plant species increase beyond natural production levels. In the current study we made the assumption that, besides the intrinsic biological and ecological characteristics of the species, the decision to cultivate and/or to conserve an overharvested wild plant species is triggered by the socioeconomic factors such as land tenure and size, origin of respondents, gender, and users' knowledge of the plant phenology. METHODS: We carried out semi-structured interviews with 178 informants involved in V. doniana exploitation. The data collected were related to socio-demographic characteristics of informants' household situation, knowledge of the biology and propagation of the species, willingness to cultivate the species, in-situ maintenance of populations, and costs associated with management of the species. According to data types we used Student's t, Spearman correlation, Kruskal-Wallis, Fisher's exact and χ2 tests to test the effects of land tenure, origin of respondents, gender and users' knowledge of plant phenology on the decision making process. Conditional inference tree models and generalized additive models were also used to identify variables which were significantly determinant in the decision to cultivate and/or to conserve the species in-situ. RESULTS: We found that men were more willing to cultivate the species than women and this is conditioned by land area available. The willingness to conserve the species in-situ depends mainly on the total land area available, the number of trees within the landscape, accessibility of the trees, land tenure, gender, location, seedling cost, and trade-off cost for conservation. People who offered more than one US dollar to acquire a seedling of V. doniana, landowners, and those who own a total land area in excess of 6.5 ha were most willing to conserve the species in-situ. CONCLUSIONS: From our findings we conclude that future management and conservation initiatives for V. doniana should first target specific user groups for sustainable exploitation of the species. Also, the Cultivation Opportunity Ratio is an important indicator for quick determination of the likelihood of farmers to engage into cultivation and conservation of the species.

Drivers of conservation and utilization of pineapple genetic resources in Benin.

Valuation of farmer knowledge has been seen as a route to promote sustainable use of plant genetic resources. In pineapple production systems in Benin, inadequate knowledge of cultivation practices can lead to a number of inconveniences including abandon of some varieties and cultivars. To understand how farmer's knowledge and cultivation practices impact the sustainable utilization of pineapple genetic resources, we surveyed 177 pineapple farmers in southern Benin. We assessed farmers' knowledge and analyzed the relationship between their knowledge and factors such as age, education, and locality of provenance. Pineapple production system was dominated by men (96% respondents). According to farmers, Smooth cayenne is international market-oriented while Sugarloaf mainly targets domestic and regional markets. All farmers recognized that Smooth cayenne provided more income (USD 5,750/ha) than sugarloaf (USD 3,950/ha) in the production systems of southern Benin. The high value of median scores in comparison with the range of possible score showed that most farmers agreed and shared relatively similar knowledge. Correlation matrix and multiple linear regressions showed a significant relationship between farmers' practices and their knowledge of the plant; their knowledge of pineapple varieties is based on fruits traits. Also, farmer's knowledge was associated with locality of provenance. Constraints and options for genetic resources conservation and utilization in the pineapple production systems in Southern Benin were discussed based on current knowledge.