Larrea nitida extract-loaded nanodispersions as a novel bio-stimulant for tomato plants

Larrea nitida Cav. (Zygophyllaceae) hydrophobic extract (LE) is rich in antimicrobial and antioxidant compounds. In our previous study, water-soluble nanodispersions without (PZ) and with LE (PZLE) were produced to facilitate their application in agriculture. The foliar treatment was carried out with water (control), PZ and PZLE thrice a week at concentrations of 33 and 100 $mg.L^{-1}$ on 1-week-old tomato seedlings (Solanum lycopersicum L. variety perita platensis). PZLE at a concentration of 100 ${\mathrm{mg}.L}^{-1}$ significantly induced a growth promotion effect and decreased the activity of the antioxidant enzymes guaiacol peroxidase (GPx) and catalase (CAT), probably due to the presence of antioxidant compounds in PZLE. However, 5 days after infection with Pseudomona syringae pv. tomato, the activity of CAT increased by 73 % compared to the control, as a response to the stress caused by the infection. Additionally, plants treated with PZLE at 33 and 100 ${\mathrm{mg}.L}^{-1}$ exhibited reductions in infection symptoms of 44 % and 76 %, respectively. As for both concentrations of PZ, no significant differences were found when compared to the control, suggesting a protective effect of PZLE. The photosynthetic parameters of the plants, such as Phi2 (${\phi }_{\mathrm{PSII}})$, non-photochemical quenching (NPQ) and the relative chlorophyll in the leaves of these plants remained unaffected, suggesting no detrimental effects of PZLE on photosynthetic efficiency. PZLE demonstrates potential as a bio-stimulant for tomato plants, offering a complementary approach to traditional agricultural inputs.