Effects of foliar boron and zinc applications on potato yield and marketability in semi-arid calcareous soils
Abstract
Boron (B) and zinc (Zn) deficiencies constrain potato ( Solanum tuberosum L.) productivity in semi-arid, calcareous soils; yet cultivar-specific responses remain insufficiently resolved. We conducted a split-plot field trial in Şanlıurfa (Türkiye) during the 2022–2023 winter season to quantify foliar B–Zn effects across eight cultivars spanning early (Lady Olimpia), mid-early (Agria, Alegria, Kafkas, Petek, Turaç, Yaprak), and late-maturing (Bahar) classes. Main plots were cultivars; subplots received foliar B–Zn at 0.0 (control), 0.5 (0.5 g L ⁻ ¹ boric acid + 1.0 g L ⁻ ¹ zinc sulfate), or 1.0 (1.0 + 2.0 g L ⁻ ¹) with four weekly sprays beginning 90 days after planting. Mixed-effects models (random: block, block×cultivar; fixed: cultivar, dose, cultivar×dose) generated estimated marginal means; we further applied Derringer–Suich desirability to jointly optimize decare yield and plot-level marketable yield. Pre-plant soil tests indicated very low plant-available B and Zn, providing a strong context for response. Both dose and cultivar×dose were significant for yield (α = 0.05), with a clear maturity-linked pattern in effect sizes. Within the mid-early group, the 1.0 dose delivered the largest gains: Petek +29.5% (4014 vs. 3100 kg da ⁻ ¹), Kafkas +28.2% (4262 vs. 3323), Yaprak +21.4% (4251 vs. 3502), Turaç +13.7%, Agria +14.4%, and Alegria +11.2%. By contrast, the early cultivar Lady Olimpia showed a limited increase (+4.4%), and the late cultivar Bahar rose +6.0%. Component traits corroborated these patterns: marketable tuber number and total tuber weight per plant increased most in responsive mid-early entries (e.g., Petek, Kafkas, Turaç), whereas several less-responsive cultivars plateaued at the 0.5 dose. Multi-criteria optimization identified Yaprak (0.5 or 1.0) and Kafkas (1.0) as Pareto-efficient choices, jointly maximizing total and marketable yield; Petek (1.0) ranked just behind. Collectively, foliar B–Zn improved productivity under B–Zn-poor conditions, but benefits were maturity-class and cultivar specific: mid-early cultivars captured the largest yield and marketability gains, whereas early and late entries showed modest responses. These findings support diagnostics-led micronutrient management and cultivar-tailored dosing, with 0.5–1.0 rates preferred for responsive mid-early types to co-optimize total and marketable yield in similar semi-arid environments.