Effect of Spraying Chitosan and Spirulina platensis Extract on the Growth and Flowering of Dianthus barbatus L.

• Baraa Daraa Ahmed Abdul Kareem A. J. Mohammad Saeed

  Author

    This study was conducted in plastic house of Research Station, Department of Horticulture and Landscape Gardening, College of Agriculture, University of Diyala, during the 2025–2026 growing season to evaluate the effect of foliar application of chitosan and Spirulina platensis extract on the growth, flowering, and ornamental quality of carnation cv. 'Husan Yousif'. The experiment included three concentrations of chitosan (0, 200, and 400 mg L⁻¹) and three concentrations of Spirulina extract (0, 100, and 200 mg L⁻¹) arranged in a factorial experiment according to a Randomized Complete Block Design (RCBD) with three replications. The results showed that foliar application of chitosan at 200 mg L⁻¹ accelerated flowering, reducing the number of days to inflorescence emergence to 67.04 days, whereas chitosan at 400 mg L⁻¹ produced the highest inflorescence diameter (60.68 mm), flowering stem length (32.02 cm), and number of florets per inflorescence (41.91 florets). Likewise, foliar application of Spirulina extract at 200 mg L⁻¹ significantly improved flowering characteristics, recording the largest inflorescence diameter (61.44 mm), the longest flowering stem (33.46 cm), the highest number of florets per inflorescence (41.72 florets), and the earliest flowering (65.85 days). The interaction between chitosan at 400 mg L⁻¹ and Spirulina extract at 200 mg L⁻¹ produced the best flowering performance, achieving the greatest flowering stem length (38.33 cm) and the highest number of florets per inflorescence (43.25 florets). These findings indicate that the combined application of chitosan and Spirulina extract effectively enhances the flowering performance and ornamental quality of carnation plants.

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