Introduction: Deficiency of elements in plants disrupts plant activities and causes changes in the production of various products, but fertilizer management can greatly affect the quantity and quality of products. Thus, one of the important needs in agricultural planning in order to achieve high yield and desired quality is to evaluate plant nutrition systems, because with correct methods of soil fertility and proper plant nutrition, the quality of products can be increased while preserving the environment. The continuous use of chemical fertilizers in the production of agricultural products has become unavoidable, which has led to a crisis of soil and water resource pollution in recent years. Therefore, extensive efforts have been initiated to find appropriate solutions to maintain the sustainability of producer ecosystems and produce high-quality agricultural products. Accordingly, today, various studies have introduced various types of biological and organic fertilizers as alternatives and sometimes supplements to chemical fertilizers, which are effective in the sustainability of agricultural production systems. In this study, the effect of applying bio-fertilizer containing Azospirillum and arbuscular mycorrhiza and poultry manure on the quantity and quality of the medicinal plant roselle (Hibiscus sabdariffa L.) was investigated.

Materials and methods: This research was conducted in a randomized complete block design with three replications in the 2021-2022 and 2022-2023 cropping season in Jiroft region. The experimental treatments included 13 different levels of nutrient sources compared to the control (no fertilizer application) including: inoculation with arbuscular mycorrhizal fungi (AMF), application of Azospirillum (Az), their combined application (AMF+Az), 100% recommended poultry manure (PM), 100% recommended CF, 50%PM+50%CF, 50%PM+AMF, 50%PM+Az, 50%PM+AMF+Az, 50%CF+AMF, 50%CF+Az, 50%CF+AMF+Az, and 25%PM+25%CF+AMF+Az.

Results and discussion: The results showed that, in addition to the effect of nutritional sources on growth indices, the highest flowering branch length was obtained from the 50%PM+Az treatment and the highest dry boll weight per plant was obtained from the 50%PM+Az and 50%PM+50%CF treatments. Also, the highest grain yield, oil percentage, and seed oil yield were observed in the 50%PM+50%CF treatment, and the highest protein percentage and seed protein yield were observed in the 50%PM+Az treatment. Based on the results of this study, the use of nutritional treatments containing poultry manure and bio-fertilizers can, in addition to improving growth indicators, increase the quantity and quality of roselle seeds.

Conclusion: According to the results, the application poultry manure and bio-fertilizers treatments can, in addition to increasing the quantitative yield of roselle seeds, also increase the quality of the seeds. In other words, the positive effect of combined application of poultry manure and biological compounds (using a combined treatment of 50%PM+Az and in some traits combining this treatment with AMF) in addition to the possibility of increasing the quantitative yield of this plant can also improve the quality of the product. In some traits, the highest amount of traits was obtained from the combined treatment of 50%PM+50%CF. In other words, although the use of mineral fertilizers is less expensive than organic compounds, the exclusive use of chemical compounds is not recommended due to the adverse effects of chemical compounds. Accordingly, it is recommended to replace integrated nutritional treatments such as the use of combined treatments of poultry manure and Azospirillum, sometimes in combination with arbuscular mycorrhizal fungi, and also the use of 50% chemical fertilizer along with poultry manure.