Effect of Biofertilization with Two Types of Cyanobacteria (Anabaena and Nostoc) and Their Application Method on the Vegetative and Root Growth Characteristics of Spearmint (Mentha spicata)

• Ruqaya Abdulbasit Ali Mahmoud &Ali muayad sultan

  Author

This study aimed to isolate, purify, and morphologically identify local nitrogen-fixing cyanobacteria (blue-green algae) from various agricultural environments in the Al-Alam district, Salah al-Din Governorate. It also aimed to evaluate their bio-efficacy as fertilizers and extracts for foliar spraying and soil drenching to support vegetative and root growth traits, as well as the essential oil yield of spearmint (Mentha spicata), as a sustainable alternative to traditional chemical fertilizers. Materials and Methods: The experiment was conducted in the glasshouse of the College of Education for Women, University of Tikrit, during the 2025-2026 agricultural season. The experiment was designed according to a Randomized Complete Block Design (RCBD) as a factorial experiment involving two factors: the first factor was cyanobacteria of the genus Nostoc, and the second was of the genus *Anabaena*. Treatments included three application methods: (foliar spray with extract, soil drench with extract, and a control treatment with distilled water only). Several morphological and physiological indicators were measured at the end of the season, including: plant height, number of leaves, leaf area, fresh and dry weights of the vegetative and root systems, and root length. Results: The results showed a statistically significant superiority for all biofertilization treatments compared to the control treatment. The interaction treatment involving soil drench with both types together (Anabaena+ Nostoc) recorded the highest significant response in most of the studied traits; it achieved a plant height of 30.67 cm, a 64% improvement over the control, while the number of leaves reached 211 leaves/plant (with the peak for individual superiority of Nostoc drench reaching 217.33 leaves/plant). The dry weight of the vegetative shoot was 4.48 g, an increase of 103.55%, while the fresh weight of the shoot was 16.57 g, a 101.82% improvement. Regarding root length and fresh weight, the drench interaction achieved a record root elongation of 39.00 cm (a 129.41% increase) and a root fresh weight of 11.53 g (a 197.14% increase). For root dry weight and leaf area, the same treatment excelled with a root dry weight of 2.58 g (a 256.32% increase) and a leaf area of 2.54 cm².

• pdf