Seed payment modality and sesame varietal traits preferences of farmers: evidence from randomized experiments in Nigeria, Senegal and Tanzania

Despite past investment in varietal development and dissemination, a central puzzle is that the adoption of improved crop varieties, with high-yielding potential among smallholder farmers in Sub-Saharan Africa remains persistently low. One plausible explanation is potential misalignment between breeder priorities and farmer preferences. Past breeding efforts have overly prioritized agronomic traits such as yield that may not fully reflect the preferences of farmers without taking into account other varietal traits and end-user (e.g., processor, consumer) requirements for quality traits, such as oil content, especially for sesame with high output market potential. Without credible estimates of what farmers value and are willing to pay for across key traits, breeding programs cannot align objectives with farmer demand. A second and less recognized potential barrier is the temporal mismatch between investment in inputs, such as improved seeds and income realization in smallholder farming systems. Farmers must purchase seed at planting months before harvest income is realized, yet many may lack the savings or credit access needed to meet upfront seed costs for improved varieties. This seasonal liquidity constraint may compress effective demand at precisely the moment purchase decisions are made, potentially creating an adoption gap that reflects a financing problem rather than or in addition to a genuine varietal traits preference problem. Standard choice experiments, which implicitly assume farmers can pay at the time of purchase, confound true preferences with liquidity-driven constraints and may produce downward-biased willingness to pay estimates for the most cash-constrained farmers. This study assesses sesame varietal preferences and tests whether seed payment modality shapes preferences of smallholder farmers. To do so, we implement a randomized discrete choice experiment among smallholder sesame farmers in Nigeria, Tanzania and Senegal. The experiment is embedded within a randomized seed payment timing design: a randomly selected treatment group of farmers is offered the opportunity of full seed payment deferred to harvest time, after income has been realized from sales of farm produce, before responding to the choice experiment, while a control group responds to the choice experiment assuming full upfront seed payment at planting time. Overall, the study generates insights on whether the puzzling improved sesame seed adoption gap is partly driven by varietal traits preference misalignment (breeding problem), seed payment modality (liquidity constraints), or both. Findings would inform breeding and financial interventions most likely to accelerate adoption among smallholder farmers.