Alleviation of Salt Stress Conditions in Some Mint Species Grown under Nanomaterials

This study was conducted in 2022 at the greenhouse facility of Kilis 7 Aralık University, Mercidabık Campus, under controlled conditions using potted plants. The effects of salinity stress on the growth parameters of Mentha spicata L. and Mentha piperita L., and the potential mitigating effects of foliar-applied quercetin (QC), graphene oxide (GO), and nanoparticles (NP) were investigated.Seeds were sown in trays on March 15 and seedlings were transplanted into 3-liter pots at the four-leaf stage, with three plants per pot. Ten days post-transplantation, QC, GO, and NP were applied at concentrations of 0, 25, and 50 mg/L for three consecutive days. After 48 hours, salinity treatments (0, 50, and 100 mM NaCl) were initiated via soil irrigation with 200 ml of 50 mM NaCl solution every two days for one week, followed by adjusted salinity concentrations for an additional two weeks. The trial was carried out using a randomized block design with three replications.Growth parameters including plant height, branch number, fresh herb weight, fresh leaf weight, and dry leaf weight were measured. Data were subjected to one-way analysis of variance (ANOVA), and significant differences among treatments were determined using Duncan’s multiple range test at p < 0.05. Results are presented as means ± standard deviation. The highest plant height in M. spicata was recorded as 52.5 cm under 25 mg/L GO + 50 mM NaCl treatment, while the lowest was 30 cm under 25 mg/L QC + 100 mM NaCl. In M. piperita, the tallest plants (43.5 cm) were observed with 25 mg/L QC application, and the shortest (14.5 cm) in the control. Branch number increased under moderate salinity but decreased with high salinity combined with NP or GO applications. The highest fresh herb weight in M. spicata (21.36 g) was recorded with QC + 50 mM NaCl, and the lowest (4.24 g) with NP + 50 mM NaCl. In M. piperita, the highest fresh leaf weights (6.32 g) were found in NP treatment, with the lowest values (1.16 g) in the control group. Dry leaf weight was positively influenced by QC treatments in both species. These findings indicate that salinity stress adversely affects growth parameters in mint species; however, quercetin and certain nanomaterials may alleviate these effects. The application of nanomaterials and phytochemicals offers promising strategies to enhance mint productivity under saline conditions.