The Impact of Biostimulants on the Yield and Quality Attributes of Essential Oil from Different Basil Varieties

Ocimum basilicum is an herbaceous plant, rich in essential oils. This research represents a groundbreaking exploration of the cultivation of Ocimum basilicum in Greece, a Mediterranean nation. It emphasizes the impact of biostimulants on various basil varieties, assessing both quantitative aspects and qualitative features. This study was conducted through a field trial at the University of Thessaly’s experimental farm located in the Velestino region. This study examined different testing varieties (V1: Lemon, V2: Siam Queen, V3: Salat, V4: Bascuro, and V5: Genovese), under different biostimulant applications (B1: control, B2: seaweed extracts, amino acids, vitamins, trace elements, polyphenols, antioxidants and mannitol; B3: plant amino acids, glutamic and aspartic acid, vitamins and other nutrients, B4: B1 and B2 combination in a 1:1 ratio). The findings highlight the significant differences in both fresh and dry yields across various basil cultivars, with Lemon basil demonstrating the most substantial yields. Specifically, the Lemon variety attained the highest dry yield, surpassing the lowest-performing cultivar by more than two times. Additionally, this research evaluated the production of essential oil per hectare, emphasizing the relationship between essential oil content and the crop’s dry yield. The results revealed considerable variability among the examined varieties, with the Lemon variety yielding nearly 65 kg ha−1, the highest among them. Biostimulant treatments (B2) led to the greatest total yields of essential oils, while the control treatments yielded the least. The chemical composition of essential oils derived from O. basilicum shows significant variability, often associated with the plants’ nutritional conditions. The application of biostimulants has led to considerable alterations in the volatile profile of sweet basil, supporting this study’s conclusions.