Boron availability appears more strongly associated with peanut yield response than zinc in sandy soil

Micronutrient limitations, particularly boron (B) and zinc (Zn), may constrain peanut productivity in coarse-textured soils. This study evaluated the effects of B and Zn fertilization on growth, yield components, and agronomic efficiency (AE) of peanut grown in sandy soil using a 4 × 4 factorial design with B rates (0, 0.006, 0.012, and 0.017 g pot−1) and Zn rates (0, 0.019, 0.038, and 0.058 g pot−1) under greenhouse conditions. Zinc significantly affected shoot dry weight, with the highest biomass observed in the control treatment (18.52 g pot−1), but had limited influence on reproductive and yield traits. In contrast, B significantly enhanced pod- and seed-related parameters, increasing total seed weight by 46–51%, with the highest mean yield (16.78–16.82 g pot−1) recorded at 0.006–0.017 g B pot−1. Principal component analysis explained 81.4% of total variance and identified pod number and seed-filling traits as the primary contributors to yield variation. Agronomic efficiency, expressed on a per-pot basis, was negative for Zn at all rates, whereas B AE reached 513.3 g seed increase g−1 B applied at 0.006 g B pot−1 and remained positive at 0.017 g B pot−1. Overall, the stronger AE and yield response to B fertilization suggest that B availability was likely a more important constraint than Zn under the studied sandy soil conditions.