Synergistic role of Foliar-Applied Nano-Fertilizer enhances drought tolerance in cluster bean (Cyamopsis tetragonoloba L.)

Drought stress during the reproductive stage critically reduces the productivity of cluster bean ( Cyamopsis tetragonoloba L.) in arid regions. This study evaluated the effectiveness of foliar-applied nano-fertilizers as a sustainable strategy to improve drought tolerance and maintain cluser bean yield. A field experiment was conducted in June 2022 at MNS-University of Agriculture, Multan, Pakistan, using two genotypes (BR-2017 and BR-2021) under different irrigation regimes. Treatments included nano-Potassium (2470 gm/ha), nano-Zinc (1235 gm/ha), nano-Boron (930 gm/ha), and their combined application (825, 415, and 310 gm/ha, respectively). The experiment followed a split-plot RCBD design with three replications. BR-2021 showed superior performance, especially with the combined nano-fertilizer treatment, resulting in notable increases in plant height (30.3 %), pods per plant (1.5 %), pod yield (7.31 %), 100-seed weight (12.4 %), photosynthetic rate (4.44 %), and protein content (7.34 %) compared to the skipped irrigation with control. Under water deficit, K, Zn, and B nano-fertilizers improved photosynthesis rate by 7.12 %, 13.2 %, and 16.34 % in BR-2021 and by 39.2 %, 37.4 %, and 40.3 % in BR-2017, respectively. Transpiration rates also increased slightly across treatments. Overall, BR-2021 showed better performance than BR-2017 in key agronomic and physiological parameters. These findings revealed that the potential of nano-fertilizers as an eco-friendly and effective tool for enhancing drought resilience and sustaining cluster bean productivity under limited water availability, thereby contributing to climate-resilient and resource-efficient agriculture. • Foliar-applied nano-K, nano-Zn, and nano-B improved the growth, physiology, and yield of cluster bean under drought condition. • BR-2021 outperformed BR-2017, exhibiting higher photosynthesis, yield, and protein content under drought condition. • Nano-fertilisers enhanced nutrient uptake and stability, synergistically mitigating the effects of drought stress.