Document Type : Research Paper

Authors

• Somayeh Badakhshan ¹
• Enayatollah Tohidi-Nejad ²
• Jalal Ghanbari ³
• Bahareh Parsa Motlagh ⁴

¹ Ph.D Student, Department of Plant Production and Genetics, Faculty of Agriculture, Shahid Bahonar University of Kerman

² Associate Professor, Department of Plant Production and Genetics, Faculty of Agriculture, Shahid Bahonar University of Kerman

³ 3- Department of Plant Production and Genetics, Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran. 4- Seed and Plant Certification and Registration Institute (SPCRI), Agricultural Research, Education & Extension.

⁴ Assistant Professor, Department of Agronomy and Plant Breeding, Faculty of Agriculture, University of Jiroft, Jiroft, Iran

Abstract

   Background and objective: One of the most critical factors influencing the production of agricultural products is the proper nutrition of plants. In addition to its positive role in increasing quantitative yield, it also affects the quality of various products. Roselle (Hibiscus sabdariffa L.) is a medicinal plant and an annual, short-day, self-fertilizing species sensitive to cold and frost. More than 300 Roselle species exist worldwide; like other plants, their growth and yield, both quantitative and qualitative, can be influenced by genetic factors and environmental conditions. Moreover, due to the importance of the quality of extracted compounds in all types of medicinal plants, greater care is required when using chemical fertilizers. This study was conducted to develop a suitable integrated nutritional program using organic and biological fertilizers to replace chemical fertilizers in Roselle cultivation.
Methodology: The field experiment was conducted using a randomized complete block design with three replications in Jiroft during the years 2021-2022 and 2022–2023. The experimental treatments included 14 nutritional sources: control (T₁), inoculation with arbuscular mycorrhizal fungi (T₂), application of Azospirillum (T₃), simultaneous application of arbuscular mycorrhizal fungi + Azospirillum (T₄), 100% recommended poultry manure (T₅), 100% recommended chemical fertilizer (T₆), 50% poultry manure + 50% recommended chemical fertilizer (T₇), 50% poultry manure + arbuscular mycorrhizal fungi (T₈), 50% poultry manure + Azospirillum (T₉), 50% poultry manure + arbuscular mycorrhizal fungi + Azospirillum (T₁₀), 50% chemical fertilizer + arbuscular mycorrhizal fungi (T₁₁), 50% chemical fertilizer + Azospirillum (T₁₂), 50% chemical fertilizer + arbuscular mycorrhizal fungi + Azospirillum (T₁₃), and 25% poultry manure + 25% chemical fertilizer + arbuscular mycorrhizal fungi + Azospirillum (T₁₄). Planting was done on June 12, and harvesting took place on December 1 in both years. Traits measured included wet and dry yield of Roselle sepals, anthocyanin content of sepals, and Hunter’s color indices (L*, a*, and b*). Additionally, to evaluate color quality and purity, three indices-hue angle (degrees), chroma, and redness—were assessed. Data analyses were performed using SAS v. 9.1, and means were compared with Duncan’s test.
Results: The findings showed significant differences among fertilizer treatments for all traits. The highest Roselle sepal yield was obtained from 50% poultry manure + Azospirillum (T₉) and 50% poultry manure + 50% chemical fertilizer (T₇), with a 55% increase compared to the control (T₁). The highest dry sepal yield was also observed in 50% poultry manure + 50% chemical fertilizer (T₇), with no significant difference from 50% poultry manure + Azospirillum (T₉). The highest anthocyanin content, with increases of 36.26% and 34.97% over the control, was recorded in poultry manure + arbuscular mycorrhizal fungi + Azospirillum (T₁₀) and 50% poultry manure + Azospirillum (T₉), respectively. These two treatments also produced the maximum red-green color index values (25.292 and 24.960), color saturation (39.980 and 39.403), and redness (10.769 and 10.282), respectively.
Conclusion: The results indicate that combined nutritional treatments containing poultry manure and biofertilizers can enhance both the quality and quantity of Roselle sepal yield. Sepals from these treatments exhibited the highest values for the measured quantitative traits. In color attributes, the highest values were also obtained from poultry manure and biofertilizer combinations. Therefore, integrated nutritional treatments involving these fertilizers appear to be a suitable alternative for reducing chemical fertilizer use while improving both the quantitative and qualitative yield of Roselle

Keywords

• Azospirillum
• anthocyanin
• arbuscular mycorrhizal
• poultry manure

Main Subjects

• Phytochemistry (extraction, identification and measurement of active components)