Effects of Chemical and Organic Fertilizers on Physiological and Biochemical Traits of Garlic (Allium sativum L.)

Abstract

This study evaluated the effects of chemical, organic, and biofertilizer treatments on the physiological, biochemical, antioxidant, and mineral characteristics of garlic (Allium sativum L.). The experiment was conducted at the Botany Department, University of Education, Faisalabad Campus, using a factorial arrangement in a completely randomized design (CRD). Twenty-five pots containing 10 kg of soil each were subjected to five treatments: T1, control (water only); T2, vermicompost (5 g pot⁻¹); T3, Nitrophos (5 g pot⁻¹); T4, oven-dry weight content (OWDC, 5 g pot⁻¹); and T5, kitchen-waste fertilizer (5 g pot⁻¹). The evaluated parameters included chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, total soluble protein (TSP), total soluble sugars (TSS), proline, ascorbic acid, catalase (CAT), peroxidase (POD), relative water content (RWC), net photosynthetic rate (Pn), transpiration, carbon-related parameters, and leaf N, P, and K concentrations. Nitrophos produced the highest values for chlorophyll a (0.782 mg g⁻¹), chlorophyll b (0.640 mg g⁻¹), total chlorophyll (1.422 mg g⁻¹), total soluble protein (6.40 mg g⁻¹), net photosynthetic rate (15.57 µmol m⁻² s⁻¹), RWC (72.50%), and leaf N, P, and K (4.43, 5.80, and 41.13 mg g⁻¹, respectively). Organic treatments produced higher levels of several biochemical and antioxidant-related parameters, with OWDC showing the highest proline (0.639 mg g⁻¹), while kitchen-waste fertilizer produced the highest total soluble sugars (6.33 mg g⁻¹), ascorbic acid (76.53 mg g⁻¹), and catalase activity (159.97 U mg⁻¹ protein). Nitrophos also recorded the highest peroxidase activity (144.77 U mg⁻¹ protein). Overall, chemical fertilizer was most effective for improving photosynthetic performance, soluble protein, and mineral accumulation, whereas organic fertilizers enhanced several biochemical and antioxidant traits. The findings indicate that combining chemical, organic, and biological nutrient sources may provide a more balanced approach for sustainable garlic production and soil health.