Aly, Amina AEliwa, Noha ESafwat, Gehan2024-03-202024-03-202024-01https://doi.org/10.1186/s12870-024-04853-8http://repository.msa.edu.eg/xmlui/handle/123456789/5903ascorbic acid, phenols, flavonoids, soluble proteins, and antioxidant activity. Results: Irradiated Na-alginate resulted in the depolymerization of Na-alginate into small molecular-weight oligosaccharides, and the best dose to use was 100 kGy. Certain chemical modifications in the general structure were observed by FTIR analysis. Two absorbed bands at 3329 cm−1 and 1599 cm−1, were recognized that are assigned to O–H and C-O stretching, respectively, and peaks achieved at 1411 cm−1 represent the COO-stretching group connected to the sodium ion. The peak obtained at 1028 cm−1 was owing to the stretching vibration of C-O. The results of TGA provided that the minimum weight reminder was in the ISA at 100 kGy (28.12%) compared to the UISA (43.39%). The images of TEM pointed out that the Na-alginate was globular in shape, with the particle distribution between 12.8 and 21.7 nm in ISA at 100 kGy. Irradiated sodium alginate caused a noteworthy enhancement in the vegetative growth traits (leaf area, stem length, head weight, and leaf number). By spraying 400 ppm, ISA showed a maximum increase in total pigments (2.209 mg/g FW), ascorbic acid (3.13 mg/g fresh weight), phenols (1.399 mg/g FW), flavonoids (0.775 mg/g FW), and antioxidant activities (82.14. %). Also, there were correlation coefficients (R values) between leaf area, stem length, head weight, and leaf number values with total pigment content, antioxidant activity, total soluble proteins, and ascorbic acid. Conclusions: The outcomes of the recent investigation demonstrated that the application of spraying irradiated Na-alginate (100 kGy) resulted in an improvement of the considered characters.enSodium alginate. Gamma ray. Chemical content. LettuceArticlehttps://doi.org/10.1186/s12870-024-04853-8