Proline and Betaine enriched nano Zinc fertilizer for growth and seed quality enhancement in drought exposed coriander

Water scarcity severely affects crop productivity, necessitating innovative solutions, such as using nanoparticles as stress regulators. This study aimed to investigate the effectiveness of zinc oxide nanoparticles (ZnO NPs) enriched with proline (ZnOP) and betaine (ZnOBt) in mitigating drought stress in coriander growth. Coriander plants were grown in pots supplemented with ZnO NPs and its derivatives. The leaves and seeds extracts were subjected to antioxidant and phenolics, flavonoid profiling. The seed oil was also characterized by gas chromatography-mass spectrometry (GC-MS) to figure out the chemical composition. Plants exposed to drought stress showed poor vegetative growth parameters. However, application of ZnO nanocomposites reducing effects of stress thus improving growth and productivity of coriander plants. Coriander plants height increased up to 84 % and 82 % under ZnOP and ZnOBt treatment compared to drought stressed plants (61.87 cm). Number of umbels increased up to 8 while yield increased by 142 % and 129 % under nanocomposites treatments. At 50 mg/kg ZnOP and ZnOBt, total phenolics contents in leaves decreased up to 22 % and 32 %, respectively while total flavonoids contents up to 11 % and 13 %, respectively. Free radical scavenging was 55 % under ZnO, 50 % under ZnOP and 57 % under ZnOBt NPs while in drought stress it was 64 %. Total antioxidant activity and total reducing power potential in plant leaves also significantly decreased upon NPs treatment. Seed yield and nutritional quality was also improved by the application of zinc nanocomposites. Oil content in seeds improved by 59 % and 37 % in presence of ZnOP50 and ZnOBt50, respectively. GC-MS analysis also showed increases in some important essential oil content of seeds like 3-hexanol, limonene, linalool, tetradecanoic acid etc. Total phenolics and flavonoids; free radical scavenging, and antioxidant potential of seeds extract decreased by nano treatment as compared to drought stress while increased as compared to control plants seeds. Proline and betaine accumulation in seeds on nanocomposite treatments also improved the seeds nutritional quality. These findings confirm that zinc nanocomposites treatment results in accumulation of various phytochemicals and quenching of oxidative stress in plants and also have positive effect on coriander seeds production and nutritional quality. These nanocomposite materials can be used to obtained better coriander crop yield even under drought conditions and this system have potential to be further applied to other crops under different stresses offering promising prospects for enhancing crop resilience and productivity • Zinc Oxide NPs primed with Proline and Betaine (ZnOP and ZnOBt NPs) mitigates drought stress. • Coriander plant morphological, biochemical characteristics are studied. • Nanofertilizer increased nutritional contents of coriander plant, seed and oil. • ZnO Nanocomposite can be used against environmental stress.