Biosynthesized hematite nanoparticles mitigate drought stress by regulating nitrogen metabolism and biological nitrogen fixation in Trigonella foenum-graecum

The widespread and increasing use of biosynthetic hematite nanoparticles (HNPs) has led to their application in agriculture. Drought poses a significant threat to crop development and production in agricultural regions around the world. Two varieties of Trigonella foenum-graecum, Afg 1 (drought tolerant) and Afg 3 (drought sensitive) were treated with 20 and 50 mgL(-1) HNPs concentrations tested under 5 and 10 days drought stress with control. Both Afg 1 and Afg 3 varieties responded most efficiently at a concentration of 50 mgL(-1) HNPs in mitigating drought stress. HNPs reduced proline, nitrate, and ammonia concentrations by 22.4%, 25%, and 37% respectively. They are involved in nitrogen regulation and accumulate in dose-dependent manner during drought stress, causing toxicity. HNPs were found to be important in positively regulating the activity of nitrogen metabolizing enzymes (p <= 0.05). Nitrate reductase, glutamine synthetase, and glutamate synthase are increased by 41%, 80%, and 63% respectively. This study suggests that HNPs enhance the ability of Trigonella foenum-graecum to maintain high nitrogen metabolism and biological nitrogen fixation. nifH gene expression increased by 21.7% under drought stress by alleviating the Fe micronutrient deficiency in plants caused by dry soil alkalinity.

Automated summary

The study found that biosynthetic hematite nanoparticles can effectively alleviate drought stress on crops and help improve their nitrogen metabolism, promoting the enhancement of biological nitrogen fixation capabilities.