Influence of Carbon Nanoparticle Concentrations and Application Stages on Growth and Quality of Broccoli (Brassica Oleracea)

In pursuit of enhancing agricultural productivity, the application of nanotechnology, particularly carbon Nanoparticles (CNP), has emerged as a promising approach to improve crop growth and quality. This study, conducted during 2022-23 at the Horticulture Research Farm and Biotechnology Laboratory of Abdul Wali Khan University Mardan, Pakistan, investigated the effects of CNP Concentrations and application stage on broccoli (Brassica oleracea var. Marathon). The experiment utilized a Randomized Complete Block Design, with foliar applications of CNPs at 0, 10, 20, 30, and 40 mg L⁻¹ applied at three growth stages (4-leaf, 8-leaf, and head stage). Data were collected on growth parameters (leaf number, plant height, stem diameter, days to head initiation), yield, and quality traits (chlorophyll A and B, carotenoids, total soluble solids (TSS), ascorbic acid, and head diameter). Results revealed that CNPs significantly enhanced broccoli performance. The highest leaf number (21.89) was recorded with 40 mg L⁻¹ at the 4-leaf stage, while maximum plant height (30.59 cm) and stem diameter (1.92 mm) were observed with 40 mg L⁻¹ at the 8-leaf stage. The fewest days to head initiation (80.44) occurred with 30 mg L⁻¹ at the 4-leaf stage. Chlorophyll A (4.84 mg/g) and B (4.43 mg/g) peaked with 30 mg L⁻¹, while carotenoids (13.51 mg/g) and ascorbic acid (0.51 mg/g) were highest at 10 and 20 mg L⁻¹, respectively. Yield (90.25 g/plant), head diameter (22.99 cm), and TSS (7.60 °Brix) were maximized with 30–40 mg L⁻¹ at the 8-leaf stage. Thus, applying 30 mg L⁻¹ CNPs at the 8-leaf stage is recommended to optimize broccoli growth and quality.