Degrading the natural bio active agents by ionizing radiation and the nusing them as growth promoting substances is a novel emerging technology to exploit the genetic potential of crops in terms of growth, yield and quality. Polysaccharides, such as sodium alginate, have proven to be wonderful growth promoting substances in their depolymerized form for various plants. The effect of depolymerized form of sodium alginate, produced by irradiating the latter by ⁶⁰Co gamma rays, was studied on Artemisia annua L. with regard to growth attributes, physiological and biochemical parameters and artemisin in content. The study revealed that their radiated sodium alginate (ISA),applied as leaf-sprays at a concentration of 20–120 mgL^-1, improved the growth attributes, photosynthetic capability, enzyme activities and artemisin in content of the plant significantly. Application of ISA at 80 mgL^-1 increased the values of the attributes studied to the maximum extent. The enhancement of leaf-artemisin in content was ascribed to the ISA-enhanced H₂O₂ content in the leaves.