Response of Catharanthus roseus to fertilization with humic acid and spraying seaweed extracts in vegetative, floral and chemical growth indicators

The experiment was conducted at the research station of the College of Agriculture, University of Kufa, during the 2024-2025 growing season, to evaluate the effect fertilization with humic acid and spraying with seaweed extracts on vegetative, floral and chemical on Catharanthus roseus. seeds of Catharanthus roseus L. plant were planted on February/20/2025. the treatments of fertilizing with hiumic acid four concentrations 0, 10, 20 and 30 mgL.-1 and foliar treatment with seaweed extracts four concentrations 0, 100, 200 and 300 mg L-1. humic acid compost was added three times at transplanting in 26 cm dia. pots while seaweed extracts was sprayed three times apply the experiment period. the treatments were applied in a factorial experiment with two factors and three replications and the experiment was implemented using a complete randomized block design (R.C.B.D) 4×4×3 = 48. were analyzed using analysis of variance (ANOVA) and comparisons were made. According to the Least Significant Difference test (L.S.D) at a probability level (0.05).the results showed that soil treated with 30 mg L^-1 hiumic acid and with seaweed extracts at 300 mg. L^-1 resulted in higher values of in plant height, number ofv leaves, number of flowers, flower diameter, leafrs content of total chlorophyll, and total soluble carbohydrates and the flower content of anthocyanin pigment. the interaction was 30 mg.L^-1 humic acid and 300 mg.L^-1 seaweed extracts, which did not differ from the interaction of humic acid at the same concentration with 200 mg.L^-1 seaweed extracts. the mentioned interaction treatments differed significantly from the individual treatments and was also significantly different from the control treatment in all the studied parameters.