Shiraz University Iran Agricultural Research 1013-9885 44 2 2025 06 01 The effects of blue-green algae Nostoc commune aqueous extract on the growth parameters, metabolite contents, and antioxidant capacity in seedlings of a local Iraqi rice (Amber) variety 1 11 8141 10.22099/iar.2025.51996.1659 EN Shaymaa Muneam Saeed Department of Plant Sciences, Faculty of Science, University of Mazandaran, Babolsar, I. R. Iran Ehsan Nazifi Department of Plant Sciences, Faculty of Science, University of Mazandaran, Babolsar, I. R. Iran Aref Sheikh Amiri Department of Plant Sciences, Faculty of Science, University of Mazandaran, Babolsar, I. R. Iran Journal Article 2024 12 23 Blue-green algae have significant potential for enhancing the productivity of various agricultural crops. In this study, the effects of <em>Nostoc commune</em> extract on the physiological parameters of a local rice variety were evaluated. The extract was prepared at a concentration of 0.5 g per 100 mL of distilled water, and rice seeds were treated with extract dilutions of 0%, 20%, 40%, 60%, 80%, and 100%. Different concentrations of <em>N. commune</em> extract produced varied physiological responses in rice. All extract concentrations significantly increased radicle length and seedling weight. Germination percentage was significantly improved by 20% and 60% treatments, while the 40% concentration notably enhanced hypocotyl length. In terms of biochemical parameters, all concentrations significantly increased metabolite content. Most concentrations also led to a significant rise in chlorophyll levels, and carotenoid content was the highest in 100% extract treatment. The 60% concentration resulted in the highest carbohydrate and protein levels. The greatest accumulation of phenols and flavonoids was observed with the 20% extract. Additionally, antioxidant capacity was significantly enhanced by the 20% and 40% concentrations. Overall, based on improvements observed in both growth and biochemical parameters, aqueous extract of <em>N. commune</em> at concentrations below 60% can be recommended as an effective biostimulant and biofertilizer for enhancing rice yield. https://iar.shirazu.ac.ir/article_8141_ebfc4d507193713ed6dd18caadcc38ac.pdf