The effectiveness of on‐farm and/or on‐station early generation yield testing was examined to maximize the genetic gains for sorghum yield under smallholder famer production conditions in West Africa. On‐farm first‐stage yield trials (augmented design, 150 genotypes with subsets of 50 genotypes tested per farmer) and second‐stage yield trials (replicated α‐lattice design, 21 test genotypes) were conducted, as well as on‐station α‐lattice first‐ and second‐stage trials under contrasting phosphorous conditions. On‐farm testing was effective, with yield showing significant genetic variance and acceptable heritabilities (0.56 in first‐ and 0.61 to 0.83 in second‐stage trials). Predicted genetic gains from on‐station yield trials were always less than from direct testing on‐farm, although on‐station trials under low‐phosphorus and combined over multiple environments improved selection efficiencies. Modeling alternative designs for on‐farm yield testing (augmented, farmer‐as‐incomplete‐block, multiple lattice, and augmented p‐rep) indicated that acceptable heritabilities (0.57 to 0.65) could be obtained with all designs for testing 150 progenies in 20 trials and 75 plots per farmer. Ease of implementation and risk of errors would thus be key criteria for choice of design. Integrating results from on‐station and on‐farm yield testing appeared beneficial as progenies selected both by on‐farm and on‐station first‐stage trials showed higher on‐farm yields in second‐stage testing.
Many efforts have been made to improve sorghum [Sorghum bicolor (L.) Moench] varieties, but adoption of improved varieties remains low. Sorghum has diverse panicle architecture and grain qualities that vary within and between races, and utilization and adoption may depend on these traits. Recent efforts in West Africa to improve local guinea race germplasm as a base material have diversified potential options: there are breeding materials with a range of panicle types with increased grain number per panicle and a range of droopiness, as well as laxness and threshability. This study was designed to expand our understanding about sorghum grain and panicle traits that are important for farmers in the Sudan savanna zone of Mali. We combined a sorghum panicle sorting activity with qualitative interviews in Mande and Dioïla to understand farmers' knowledge and preferences about sorghum characteristics. A total of 20 panicle sorting activities and 20 interviews were conducted with men and women sorghum producers. Based on their roles and responsibilities in sorghum production and processing, farmers associated specific panicle types, plant types, and grain traits with aspects of pest control, threshability, storage duration, and yield. Farmers preferred open panicles and droopy architecture for disease and pest control; hard grains for storage and appropriate ratios of flour and grits; high density of grain on the panicle for yield; and specific glume qualities for threshability. Breeding programs need to consider these regional preferences and gender roles to develop appropriate material and increase adoption of productive varieties.
Malian farmers’ traditional system for managing seed of sorghum, an indigenous crop of vital importance for food security and survival, can be conceptualized as a commons. Although this system maintains a wide range of varieties and helps ensure access to seed, its ability to create and widely disseminate new varieties to meet evolving opportunities and challenges is limited. A network of farmer groups, public breeding programs, and development organizations collaborating in decentralized creation and dissemination of sorghum varieties in Mali is examined regarding (1) how the network developed and what activities it conducts; (2) the resulting varietal diversity, varietal performance and organizational models; and (3) the elements of the traditional seed system that were maintained, strengthened or transformed. A single-case study approach was used that relies on published literature, official catalogues of released varieties and a database of farmer seed-cooperative requests for foundation seed. The functioning of the network and its varietal-, seed-, and organizational- outcomes are documented and the elements of the traditional sorghum seed system that are maintained or strengthened are analyzed. The evolution of the network’s reliance on commoning as a social process and its strengthening of core Seed Commons features are discussed with a view to the network’s contributions to targeted development outcomes and potential replicability. The case demonstrates how creating a framework for collaboration, enabling actors and organizations to take on collective responsibility while maintaining distributed decision-making at local level, opens opportunities for transforming farming- and food-systems towards sustainability and resilience.
Sorghum, a major crop for income generation and food security in West and Central Africa, is predominantly grown in low-input farming systems with serious soil phosphorus (P) deficiencies. This study (a) estimates genetic parameters needed to design selection protocols that optimize genetic gains for yield under low-phosphorus conditions and (b) examines the utility of introgressed backcross nested association mapping (BCNAM) populations for diversifying Malian breeding materials. A total of 1083 BC1F5 progenies derived from an elite hybrid restorer “Lata-3” and 13 diverse donor accessions were evaluated for yield and agronomic traits under contrasting soil P conditions in Mali in 2013. A subset of 298 progenies were further tested under low-P (LP) and high-P (HP) conditions in 2014 and 2015. Significant genetic variation for grain yield was observed under LP and HP conditions. Selection for grain yield under LP conditions was feasible and more efficient than the indirect selection under HP in all three years of testing. Several of the BCNAM populations exhibited yields under LP conditions that were superior to the elite restorer line used as a recurrent parent. The BCNAM approach appears promising for diversifying the male parent pool with introgression of diverse materials using both adapted Malian breed and unadapted landrace material from distant geographic origins as donors.
The identification of haplotypes influencing traits of agronomic interest, with well-defined effects across environments, is of key importance to develop varieties adapted to their context of use. It requires advanced crossing schemes, multi-environment characterization and relevant statistical tools. Here we present a sorghum multi-reference back-cross nested association mapping (BCNAM) population composed of 3901 lines produced by crossing 24 diverse parents to three elite parents from West and Central Africa (WCA-BCNAM). The population was characterized in environments contrasting for photoperiod, rainfall, temperature, and soil fertility. To analyse this multi-parental and multi-environment design, we developed a new methodology for QTL detection and parental effect estimation. In addition, envirotyping data were mobilized to determine the influence of specific environmental covariables on the genetic effects, which allowed spatial projections of the QTL effects. We mobilized this strategy to analyse the genetic architecture of flowering time and plant height, which represent key adaptation mechanisms in environments like West Africa. Our results allowed a better characterisation of well-known genomic regions influencing flowering time concerning their response to photoperiod with Ma6 and Ma1 being photoperiod sensitive and candidate gene Elf3 being insensitive. We also accessed a better understanding of plant height genetic determinism with the combined effects of phenology dependent (Ma6) and independent (qHT7.1 and Dw3) genomic regions. Therefore, we argue that the WCA-BCNAM constitutes a key genetic resource to feed breeding programs in relevant elite parental lines and develop climate-smart varieties.
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