Application of magnesium oxide nanoparticles to improve sweet basil (Ocimum basilicum L.) productivity in total control environment agriculture

Relevance. The rising demand for spicy crops is driving the development of their year-round production at urban farms. Magnesium oxide nanoparticles (MgO-NPs) have great potential for use in total control environment agriculture of green crops due to their eco-friendliness and ability to stimulate growth and secondary metabolite accumulation. This study aims to determine effective MgO-NPs concentrations for stimulating growth, photosynthesis, and essential oil accumulation in sweet basil. Materials and Methods. MgO-NPs (6–7 nm in size), produced by laser ablation, were applied in three foliar applications, 10 days apart, beginning with the emergence of the first true leaves of sweet basil cultivar Zhigolo. Nanoparticles were used at concentrations of 25, 50, 75, 100, 150, 200, and 500 mg/l. Control plants were sprayed with distilled water. On the 60th day of cultivation, the following parameters were measured: plant height, leaf count, fresh and dry weight, total chlorophyll, anthocyanins, and essential oil content. Results. MgO nanoparticle treatments at concentrations of 100 and 150 mg/l increased the number of leaves by 65 and 60 %, and the fresh weight of basil plants by 55.7 and 83.4 %, respectively. Treatment at concentration of 150 mg/l contributed to an increase in plant height by 51.6 %. An increase in dry weight was observed in all treatment variants with MgO-NP concentrations 75 mg/l and above. When using treatments of 150, 200, and 500 mg/l, the greatest reliable increase in dry mass (by 43, 56, and 37 %) and total chlorophyll content (by 38, 77, and 33 %) was observed. Maximum accumulation of essential oils (more than 2 times) was observed at concentration of 50 mg/l. The composition of essential oils also altered: the highest content of linalool was observed at 25 mg/l, eugenol – at 50 mg/l, and eucalyptol – at 75 mg/l.