Comparative agronomic performance of foliar-applied nano-biochar and potassium nanoparticles in enhancing nutrient uptake, growth, and yield of Triticum aestivum L.

The growing demand for sustainable crop production necessitates innovative nutrient management strategies based on waste valorization. In this study, two waste-derived nanofertilizers, nano-biochar (NBC) and potassium nanoparticles (KNPs), prepared via green routes were evaluated as foliar potassium sources in Triticum aestivum against conventional muriate of potash (MOP). Physicochemical characterization confirmed successful synthesis of stable nanofertilizer, with NBC exhibiting a porous, functionalized structure favoring nutrient retention, while KNPs displayed relatively spherical morphology enabling rapid uptake. Both NBC and KNPs achieved 100% germination, representing a 10–35% increase over MOP (positive control) 87.5% and water (negative control) 75%. At the seedling stage, NBC achieved the highest overall biomass, increasing shoot fresh and dry weights by >9 fold and >11 fold over the water and >7 fold and >11 fold over MOP, respectively. KNP also enhanced overall biomass relative to both control treatments; however, it was superior to NBC in promoting root elongation, by achieving (9.90 cm) compared with NBC (9.10 cm), representing 1.65 fold and 1.52 fold increases over MOP and 2.08 fold and 1.91 fold over the water, respectively. Under natural field conditions, NBC demonstrated superior efficacy over all other treatments. It boosted plant height, tiller number, and grain yield by 105%, 103%, and 118%, respectively, compared to the water, and by 30%, 37%, and 47% against MOP. Similarly, KNPs achieved notable yield enhancements, increases by 83%, 65%, and 74% over the water, and 16%, 11%, and 17% over MOP. Biochemically, NBC triggered pronounced metabolic shifts boosting protein levels 93% (vs. water) and 73% (vs. MOP), proline by 55% and 41%, phenolic by 87% and 65%, chlorophyll b by 106% and 104%, and carotenoids by 132% and 110%, respectively. While KNPs showed more modest biochemical impacts. Overall, under the conditions tested , NBC and KNPs exhibit complementary mechanisms: NBC ensures sustained nutrient release and metabolic stability, whereas KNPs facilitate rapid nutrient assimilation. These findings highlight the potential of waste-derived nanofertilizers in enhancing productivity, supporting circular bioeconomy, and advancing sustainable agriculture and food security.