The effect of different doses of foliar application of graphene oxide nanoparticles on the yield and quality of sweet basil (Ocimum basilicum L.) cultivated through organic and chemical fertilizers

In the current PhD thesis survey, the effects of various graphene oxide nanoparticle (nGO) doses (100, 200, 300, 500 mg L-1) applied foliarly on some agronomic characteristics and biological activity of sweet basil (Ocimum basilicum L. var. dino) grown by using farmyard manure (A: 30 ton ha-1) and NPK (K: 90:60:60 kg ha-1) was investigated. The research was carried out as a randomized complete split plot in random blocks design and consisted of 11 parcels (Control, A, K, A+nGO100, A+nGO200, A+nGO300, A+nGO500, K+nGO100, K+nGO200, K+nGO300, K+nGO500). Two cuttings were done during two growing seasons (2022-23). Regarding agronomic characteristics, farmyard manure applications had consequential superiority than others. However, with the enhance in nGO doses, there was a significant increase in agronomic parameters. The highest fresh and dry herb yields were determined as 28019 and 4984 kg ha-1, respectively, in the A+nGO500 treatment in the 1st year. The highest amounts of fresh herb (89.2 g), dry herb (15.9 g), fresh leaf (57.5 g), dry leaf (10.8 g), fresh stem (31.7 g), and dry stem (5.1 g) per plant were also obtained from A+nGO500 treatment in the 1st year. The highest volatile oil (VO) mean value was found in the 1st year (69%), and the control group had the highest content (0.82%). Contrary to agronomic characteristics, as the nGO doses increased, the VO contents reduced. Based on the GC/FID-MS analysis, linalool (48.8-57.92%) was found as the major component. Eugenol (16.62-26.24%), 1,8-cineole (5.11-10.66%), cis-α-bergamotene (3.37-8.05%), γ-cadinene (1.38-2.67%) were emerged as other main volatile components. Although nGO treatments had no effect on antioxidant activity in leaf extract samples, it was significant in VO samples. The highest activity was observed in the control group. The superlative DPPH and FRAP activities of the extracts were determined as 88.35% and 250.30 µg TEs mg-1, respectively, and the activities of the VO were 68.22% and 253.5 µg TEs ml-1, respectively. The highest total phenolic and flavonoid amounts of the extracts were specified as 96.09 µg GAEs mg-1 and 8.78 µg QEs mg-1, respectively. As a result of FT-IR analysis, no nGO residue was found in dry leaves. Based on the general findings of the research, the agronomic characteristics of sweet basil improved with the application of NPK, farmyard manure and nGO doses.