Response of Okra Growth and Yield to Plant Density Management and Bio-Stimulants (Vitamin E and Humic Acid)

• Aziz Mahdi Abd Al-Shammari NOOR FARAJ YASEEN

  Author

   A field experiment was conducted during the spring growing season of 2025 at the Vegetable Research Farm, Department of Horticulture and Landscape Gardening, College of Agriculture, University of Diyala, Baqubah, Diyala, Iraq (33°40′49″ N, 44°35′39″ E), to investigate the individual and interactive effects of plant density, soil-applied humic acid, and foliar-applied α-tocopherol on the growth, biochemical characteristics, yield components, and pod quality of okra. The experiment followed a split-split plot arrangement within a randomized complete block design (RCBD) with three replications. Treatments comprised two plant densities (one and two plants hill⁻¹), two humic acid levels (0 and 10 kg ha⁻¹), and four α-tocopherol concentrations (0, 50, 100, and 200 mg L⁻¹). Low plant density (D₁), humic acid at 10 kg ha⁻¹ (H₁), and α-tocopherol at 200 mg L⁻¹ (F₃) significantly increased leaf carbohydrate, N, P, and K contents, individual plant yield, and fruit diameter compared with their respective controls. The highest values were consistently obtained with the combined treatment D₁H₁F₃, which recorded 29.26% carbohydrates, 4.010% N, 0.578% P, 4.500% K, 554.00 g plant⁻¹ yield, and 2.15 cm fruit diameter, whereas the untreated high-density treatment (D₂H₀F₀) produced the lowest values. Overall, the combined application of reduced plant density, humic acid, and α-tocopherol was more effective than individual treatments in enhancing the biochemical status, productivity, and fruit development of okra.

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