article · Frontiers in Agronomy
Expanding quinoa cultivation into warm, semi-arid regions exposes the crop to heat and nutrient imbalances that current fertiliser practices do not address. Field and pot trials in Morocco examined five potassium application rates across three quinoa genotypes under varying soil and temperature conditions. In high-potassium soils exposed to high temperatures, the high-vigour genotype G41 suffered a 96 percent yield collapse at high fertiliser rates, despite performing well under cooler conditions and in potassium-poor soils. The collapse did not occur under controlled moderate temperatures, confirming heat as a critical driver. The vulnerability of G41 was linked to its large canopy, which created a high demand for calcium and magnesium that was disrupted by excess potassium. These findings show that potassium fertiliser guidelines must account for soil properties, canopy vigour, and expected heat stress.
As climate change forces agriculture into hotter, drier regions, standard fertilisation advice can unexpectedly fail. This study shows that excessive fertiliser under heat stress can destroy crop yields in vigorous varieties by disrupting nutrient uptake. Understanding how plant traits interact with heat and soil nutrients helps agronomists design better management practices to protect food production in vulnerable climates.
This research provides applied insights that could inform site-specific fertiliser management tools, agronomic advisory services, and breeding programmes selecting quinoa for hot, semi-arid environments. Agronomists, extension services, and farm managers could use these findings to refine potassium application guidelines based on local soil tests and seasonal temperatures. The work represents applied field and pot research that requires regional validation before formal commercial deployment as agronomic recommendations.
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Quinoa expansion into heat-prone semi-arid environments increasingly exposes the crop to combined abiotic stresses for which current potassium (K) fertilization guidelines are poorly calibrated. Whether genotype-specific traits modulate crop response to this combined stress remains unknown. We tested five K rates (0–200 kg K 2 O ha - ¹) on three contrasting quinoa genotypes across two Moroccan field sites differing in soil K status (715 vs. 106 mg K 2 O kg - ¹), CEC (18.0 vs. 1.2 meq 100 g - ¹), and thermal regime (Tmax 38.2 °C vs. 27.4 °C during grain filling), complemented by a controlled-temperature pot experiment. At the K-rich, heat-prone site, G41 grain yield collapsed 96% between K120 and K150, whereas at the K-poor, moderate site, the same genotype responded linearly to K200 (AE = 0.46 g g - ¹). The pot experiment showed that identical soil under controlled temperature (Tmax < 28 °C) did not show yield collapse, indicating that heat stress is a critical co-factor in this system. At baseline (K0), G36 exhibited a higher tissue K/Ca ratio (8.28) than G41 (1.95), yet maintained stable yields, indicating that constitutive tissue cation balance alone does not predict vulnerability to yield collapse; instead, G41’s large canopy (LAI 2.50 vs. 0.54) generated far higher absolute Ca² + /Mg² + demand. K fertilization restructured root architecture from absorptive to transport-dominated without changing biomass. We propose demand-side vulnerability, where yield collapse is consistent with the convergence of K-induced cation suppression, heat-amplified Ca² + /Mg² + demand, and genotype-specific canopy scaling. This finding suggests that combined abiotic stress and nutrient disorder can produce outcomes unpredictable from either stressor alone, and that K recommendations must integrate soil K/CEC status, genotype vigor, and expected thermal regime.
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DOI: 10.3389/fagro.2026.1857637
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