Bioactive, Antioxidant, and Nutritional Responses of Garlic (Allium sativum L.) to Fertilization Regimes

Garlic (Allium sativum L.) is a significant crop cultivated worldwide for its culinary, nutritional, and medicinal value. This study aimed to evaluate the effects of different fertilization regimes on the bioactive compounds, antioxidant activity, nutritional value, and mineral composition of garlic. The field experiment was conducted at the Institute of Field and Vegetable Crops, in three replications. Fertilization significantly influenced the bioactive compounds, antioxidant activity, nutritional quality, and mineral composition of garlic. Cattle manure proved to be the most effective treatment, increasing protein (by approx. 5.1%), total sugars (17.9%), sucrose (24.9%), sulfur content (7.2%), total phenolics (3.1%), flavonoids (30.7%), and antioxidant activity (by 5.2-23.1% depending on the assay) compared to the control, indicating superior nutritional and functional quality. Multivariate analyses highlighted the significant impact of fertilization regimes on garlic quality, with mineral fertilizer, control (treatment without fertilizer application), and cattle manure enhancing bioactive compounds, antioxidant activity, and nutritional composition. Fertilization had limited effects on macroelements, although cattle and sheep manure increased nitrogen and sulphur contents, while molasses reduced phosphorus and potassium levels. Organic fertilization significantly modified microelement composition, with sheep manure notably increasing zinc and copper, while most fertilizers reduced boron, iron, and sodium contents compared with the control. Animal-based fertilizers, particularly cattle manure, provide a sustainable alternative to mineral fertilization, enhancing garlic's dry matter, nutritional and bioactive compounds, and antioxidant activity.