Abstract
To enhance groundnut yields in Senegal, research generated technical proposals. However, a systemic perspective is necessary to assess their performance within the context of farmers' fields. We evaluated three short-cycle groundnut varieties-Fleur 11, 55-33, and 55-437-on two farmers' fields with different soil fertility levels, and considering two levels of mineral fertilization and rhizobial inoculation. The trials were conducted in 2018, a year characterized by a prolonged rainfall break during the vegetative phase of the crop. Varieties 55-33 and 55-437 achieved half of their potential yield, while Fleur 11 achieved only one-quarter. The Fleur 11 variety was significantly affected by fungal diseases, leading to seedling mortality and pod rot, particularly on the less fertile field. The effect of fertilizer application on yields was minimal in the least fertile field. With an average of 114 nodules per plant, the varieties demonstrated a good nodulation capacity, indicating that biological nitrogen fixation was potentially significant. Fertilizer application enhanced nodulation, suggesting that nutrient availability, especially phosphorus, was a limiting factor for symbiotic nitrogen fixation in these agroecosystems. Mycorrhization was intense, especially in the least fertile soil. Bacterial inoculation showed not effect on the measured variables.
Stepwise regression analysis revealed that variability in seed yield was primarily associated with soil carbon content and crop damages from soil-borne diseases, whereas fodder yield was mainly linked to the number of nodules per plant. Although often overlooked in current crop models, soil-borne diseases represent a major barrier to improving groundnut yields. Symbiotic interactions with soil organisms appear to be of critical importance in the studied agroecosystems. Combining diseases resistance, strong potential symbiosis with soil microbes, and a favorable response of fertilizer, varieties 55-33 and 55-437 are valuable options for enhancing the productivity and resilience of groundnut crops in marginal environments.