تأثير توليفات النتروجين والحديد والرش بمستخلص الطحالب البحرية في بعض صفات النمو والحاصل والمركبات الفعالة لنبات الحلبة

Effect of Nitrogen, Iron Combinations and Spraying with seaweed extract on Some growth, yield and active substance of Fenugreek Plant

Abstract

A field experiment was carried out in the experimental field of Ibn Al-Bitar Preparatory Vocational School, affiliated with the Directorate of Education in Holy Karbala, during the winter seasons of 2023-2024 and 2024-2025. The study aimed to investigate the effect of nitrogen and iron combinations and foliar application of seaweed extract on growth, yield, and active compound traits of fenugreek plants. The experiment was arranged in a Randomized Complete Block Design (RCBD) with a split-plot arrangement, comprising two factors. The first factor consisted of six combinations of soil-applied nitrogen (kg N ha⁻¹) and foliar-applied iron (mg FeL⁻¹):T1(N0+Fe0), T2(N0+Fe50),T3(N75+Fe0), T4(N75+Fe50), T5 (N150+Fe0), and T6(N150+Fe50).The second factor involved three concentrations of seaweed extract: A0 (spraying with distilled water only), A1 (1 g L⁻¹), and A2 (2 g L⁻¹). The experiment was conducted with three replications.
The results demonstrated the superiority of the nitrogen and iron combination T6 (150 kg N ha⁻¹ + 50 mg Fe L⁻¹), which was not significantly different from treatment T4 (75 kg N ha⁻¹ + 50 mg Fe L⁻¹). This treatment recorded the highest mean values for plant height (50.30 and 55.46 cm), number of branches (4.88 and 4.44 branches plant⁻¹), and number of leaves (81.80 and 88.33 leaves plant⁻¹) for the two consecutive seasons, respectively. It also resulted in the highest number of pods per plant (88.55 pods plant⁻¹), number of seeds per pod (15.29 seeds pod⁻¹) in the first season, and 1000-seed weight (12.14 and 13.50 g) for both seasons. Additionally, T6 produced the highest seed yield (1422 kg ha⁻¹) in the first season, biomass yield (4824 kg ha⁻¹) in the second season, and harvest index (28.50%) in the first season. Furthermore, T6 led to superior leaf nutrient concentrations, including nitrogen (2.49% and 2.27%) and phosphorus (0.66% in the first season), as well as iron content (53.00 and 33.92 mg kg⁻¹) for both seasons. Seed quality was also enhanced under T6, showing higher nitrogen (2.87%), phosphorus (0.37% in the first season), and iron content (63.07 mg kg⁻¹ in the second season). This treatment also increased seed protein concentration (17.94%), total alkaloids (3.52 mg per 100 mg), total glycosides (825.40 mg per 100 g in the first season), and Vitamin C content (13.01% and 9.03% for both seasons). Moreover, T6 significantly improved seed fatty acid profiles, including oleic acid (9.16%), linoleic acid (9.06% in the first season), palmitic acid (4.98% and 4.30%), myristic acid (12.22% and 10.44%), and stearic acid (11.65% in the second season) compared to all other treatments.
The results also indicated the significant superiority of the 2 g L⁻¹ seaweed extract (Acadian) foliar spray, which was not significantly different from the 1 g L⁻¹ concentration. This treatment yielded the highest averages for plant height (48.02 and 54.46 cm), number of branches (4.63 branches plant⁻¹ in the first season), number of leaves (87.57 leaves plant⁻¹), leaf area (7091.7 cm²), and leaf area index (0.91) in the second season. It also resulted in the highest number of pods per plant (85.92 and 90.80), number of seeds per pod (14.80 and 14.50), 1000-seed weight (12.20 g in the second season), seed yield (1366 and 1163 kg ha⁻¹), biomass yield (5013 kg ha⁻¹ in the first season), and harvest index (27.27% and 28.39%). Nutritionally, the 2 g L⁻¹ extract enhanced leaf nitrogen (2.42% and 2.26%), phosphorus (0.64% in the first season), potassium (2.24% and 2.14%), and iron content (51.54 and 34.17 mg kg⁻¹ dry weight). It also improved seed nitrogen (2.47%), phosphorus (0.25% in the second season), potassium (1.98% and 2.32%), iron content (93.13 mg kg⁻¹ dry weight in the first season), protein concentration (15.45% in the second season), Vitamin C (11.56%), oleic acid (8.03% in the first season), linoleic acid (7.91% and 10.28%), myristic acid (11.22% and 9.39%), and stearic acid (7.99% in the second season) compared to the 1 g L⁻¹ concentration and the control treatment, which recorded the lowest averages for most traits. The interaction between the nitrogen-iron combination T4 (75 kg N ha⁻¹ + 50 mg Fe L⁻¹) and the 2 g L⁻¹ seaweed extract was superior , showing no significant difference from the T4 interaction with the 1 g L⁻¹ concentration. This interaction produced the highest values for number of leaves (93.65 leaves plant⁻¹), leaf area (980.20 cm²), and leaf area index (0.98) in the second season, as well as the number of pods (93.08 pods plant⁻¹) in the first season. Furthermore, the interaction between the T6 combination (150 kg N ha⁻¹ + 50 mg Fe L⁻¹) and the 2 g L⁻¹ seaweed extract demonstrated significant superiority , with no significant difference from the T6 interaction with the 1 g L⁻¹ concentration. This interaction yielded the highest plant height (61.53 cm), number of branches (5.88 branches plant⁻¹ in the first season), number of seeds per pod (15.91 and 15.40 for both seasons), 1000-seed weight (13.85 g in the second season), leaf nitrogen concentration (2.60%), leaf potassium concentration (2.64% in the first season), leaf iron content (37.98 mg kg⁻¹ in the second season), and seed palmitic acid concentration (5.40% in the first season).