This study was conducted as a greenhouse factorial experiment based on a completely randomized design to investigate the effects of salinity stress at three levels (0 dS m−1 (control), 3 dS m−1 (moderate stress), and 6 dS m−1 (severe stress) and the application of liquid seaweed extract at five levels [control (NPK), 1% and 2% Sargassum, and 1% and 2% Spirulina] on the morphological, physiological, and phytochemical characteristics of ornamental violets (Viola × wittrockiana). Analysis of variance results showed that the main and interactive effects of salinity stress and seaweed extract were significant on all studied traits. The highest number of leaves (mean: 68.67), leaf dimensions (length: 4.07 cm, width: 2.50 cm, area: 9.60 cm²), petiole length (4.97 cm), number of lateral branches (10.5), main stem diameter (2.57 cm), crown diameter (4.40 cm), and flower diameter were observed in the treatment with no salinity stress and 2% Sargassum extract. Severe salinity stress (6 dS m−1) without seaweed extract significantly reduced these traits. The highest fresh root weight (26.67 g), dry root weight (8.63 g), root length (19.67 cm), number and longevity of flowers, and the highest levels of total chlorophyll (3.57 mg g−1 FW) and carotenoids (1.98 mg g−1 FW) were measured under no stress conditions with the application of 2% Sargassum extract. The use of seaweed fertilizers increased the synthesis of proline in ornamental violets, with the highest levels of (9.17 mg g−1 FW) observed under severe stress (6 dS m−1) with 2% Sargassum extract. Phytochemical compounds (total phenol: 45.67 mg GAE g−1 DW, total flavonoids: 36.00 mg QUE g−1 DW) and antioxidant activity (85.33%) peaked under moderate stress (3 dS m−1) with 2% Sargassum extract, indicating the stimulatory role of mild stress in secondary metabolite production. Overall, Sargassum extract showed higher efficacy than Spirulina in mitigating salinity-induced damage and improving growth indices. These findings highlight the potential of seaweed extracts, particularly Sargassum, as a biological strategy to enhance the salinity stress tolerance of ornamental violets. This study indicates that Sargassum extract can be considered a promising biostimulant for enhancing salinity tolerance in ornamental pansy.

The effect of seaweed extract application under salinity stress on growth characteristics and antioxidant response of ornamental pansy (Viola × wittrockiana)

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2026年7月9日

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Majid Maleki,
Sepideh Kalateh Jari,
Ali Mohammadi Torkashvand

摘要

This study was conducted as a greenhouse factorial experiment based on a completely randomized design to investigate the effects of salinity stress at three levels (0 dS m⁻¹ (control), 3 dS m⁻¹ (moderate stress), and 6 dS m⁻¹ (severe stress) and the application of liquid seaweed extract at five levels [control (NPK), 1% and 2% Sargassum, and 1% and 2% Spirulina] on the morphological, physiological, and phytochemical characteristics of ornamental violets (Viola × wittrockiana). Analysis of variance results showed that the main and interactive effects of salinity stress and seaweed extract were significant on all studied traits. The highest number of leaves (mean: 68.67), leaf dimensions (length: 4.07 cm, width: 2.50 cm, area: 9.60 cm²), petiole length (4.97 cm), number of lateral branches (10.5), main stem diameter (2.57 cm), crown diameter (4.40 cm), and flower diameter were observed in the treatment with no salinity stress and 2% Sargassum extract. Severe salinity stress (6 dS m⁻¹) without seaweed extract significantly reduced these traits. The highest fresh root weight (26.67 g), dry root weight (8.63 g), root length (19.67 cm), number and longevity of flowers, and the highest levels of total chlorophyll (3.57 mg g⁻¹ FW) and carotenoids (1.98 mg g⁻¹ FW) were measured under no stress conditions with the application of 2% Sargassum extract. The use of seaweed fertilizers increased the synthesis of proline in ornamental violets, with the highest levels of (9.17 mg g⁻¹ FW) observed under severe stress (6 dS m⁻¹) with 2% Sargassum extract. Phytochemical compounds (total phenol: 45.67 mg GAE g⁻¹ DW, total flavonoids: 36.00 mg QUE g⁻¹ DW) and antioxidant activity (85.33%) peaked under moderate stress (3 dS m⁻¹) with 2% Sargassum extract, indicating the stimulatory role of mild stress in secondary metabolite production. Overall, Sargassum extract showed higher efficacy than Spirulina in mitigating salinity-induced damage and improving growth indices. These findings highlight the potential of seaweed extracts, particularly Sargassum, as a biological strategy to enhance the salinity stress tolerance of ornamental violets. This study indicates that Sargassum extract can be considered a promising biostimulant for enhancing salinity tolerance in ornamental pansy.